SAT Writing: Logical Comparisons and Idioms

A single comparison question can swing on three words you would never hear yourself say wrong out loud. Read this sentence the way the digital test presents it: “The annual rainfall in Seattle is greater than Phoenix.” Nothing in your ear flinches. The sentence sounds finished, even confident. Yet it is broken, and the College Board knows that most test-takers will glide right past the flaw because speech tolerates what the written standard does not. Rainfall, a quantity, is being measured against Phoenix, a city. The two sides of the scale hold different kinds of things, so the balance is false. The repair is small and surgical: “greater than that of Phoenix.” That fix is worth a point, and the same logic, once you can see it, recurs on every form.

This guide is built around two skills that quietly drain points from strong writers who trust their instincts. The first is the logical comparison: making sure that whatever sits on the left of “than” or “as” matches, in kind, whatever sits on the right. The second is the idiomatic expression: choosing the one preposition that a fixed English phrase demands, where “different from” is standard and “different than” is the trap, where you are “prohibited from” doing something and never “prohibited to.” Neither skill rewards intuition. Both reward a rule and a checklist. By the end you will carry one portable test for comparisons, the equal-sign test, and a reference set of the twenty-five prepositional pairings the assessment leans on most.

What the standard account misses is that these two error families look like grammar but behave like logic and memory. A comparison error is a reasoning slip dressed as a sentence. An idiom error is a vocabulary fact dressed as a grammar rule. Treat them that way and the fog lifts. You stop asking “does this sound right” and start asking “can I draw an equal sign here” and “is this the standard preposition for this verb.” Those two questions, asked deliberately, convert a fuzzy ear skill into something you can drill, check, and bank.

The payoff compounds. Logical comparisons and idiomatic phrasing both fall under Standard English Conventions, the rule-governed half of the Writing content, and conventions questions reward exactly the kind of student who replaces guessing with a procedure. The reader who can name the flaw, apply the repair, and move on in twenty seconds is the reader who finishes the module with time to spare and points banked. Everything below exists to make you that reader.

Where comparisons and idioms sit in the Writing content

The Reading and Writing portion of the digital exam blends reading comprehension, rhetoric, and grammar into one section delivered across two modules, and the grammar items live under a banner the test calls Standard English Conventions. Comparisons and idioms are two members of that family, sitting alongside subject-verb agreement, pronoun clarity, punctuation, parallel structure, and verb tense. The College Board does not publish a fixed tally of how many conventions items appear, and the adaptive format means your second module shifts in difficulty based on your first, so the safest framing is that comparison and idiom items appear often enough to matter and cluster toward the harder routing when they do. A student aiming above the middle band cannot afford to treat them as rare.

Comparison and idiom questions wear a recognizable costume. The prompt gives you a sentence with a blank or an underlined stretch, and the four choices differ in one small spot: a preposition swaps, a phrase like “that of” appears in one option and vanishes in another, or a noun on the right side of “than” changes form. The question never asks “is this a comparison error.” It simply offers four versions and trusts you to pick the one that is both grammatical and logical. That silence is the difficulty. You have to supply the diagnosis yourself, which is why a named test and a memorized list beat instinct every time.

Are comparisons and idioms tested in Module 1 or Module 2?

Both. Conventions items appear throughout the Reading and Writing section, and because the second module adapts to your first-module performance, a strong start tends to route you toward harder comparison and idiom variants later. Plan to meet these in either module and to see the trickier forms if you are scoring well.

The reason these two skills get grouped in this guide is that they share a failure mode. In each case, your ear has been trained by conversation, by social media, by the way people actually talk, and conversation is a lax editor. People say “different than” constantly. People compare a city’s weather to another city without naming the second city’s weather. The spoken language shrugs. The written standard tested here does not shrug, and the gap between what sounds acceptable and what is correct is precisely the gap the question lives in. Recognizing that gap is half the battle; the procedures below close the rest of it.

There is a strategic dimension worth naming early. Because these items hinge on a single small swap, they are fast once diagnosed. A reader who knows the equal-sign test can resolve a faulty comparison in well under thirty seconds, banking time for the reading-heavy items that genuinely require slow work. The conventions questions, comparisons and idioms among them, are where a prepared test-taker buys back the clock. For a fuller map of how the rule-governed items fit the whole section, the complete grammar reference for the Digital SAT lays out every conventions family and how the section weights them, and the foundational SAT grammar rules guide covers the broader terrain these two skills sit within.

The mechanics: what a logical comparison actually requires

Strip a comparison down to its skeleton and you find a balance with two pans. On one pan sits the thing being compared; on the other sits the thing it is compared to. The grammar of the sentence demands that those two pans hold items of the same category. You may compare a quantity to a quantity, a person to a person, a city to a city, a year’s data to another year’s data. What you may not do is compare a quantity to a place, a person’s work to the person, or one team’s record to another team. When the categories mismatch, the comparison is illogical even when every word is spelled correctly and the verb agrees.

The grammatical machinery that fixes a mismatch is small and consists of three repair tools. The first is the phrase “that of” for singular nouns and “those of” for plural nouns, which inserts an invisible stand-in for the repeated noun. “The climate of Norway is milder than Russia” becomes “milder than that of Russia,” where “that” silently means “the climate.” The second tool is the possessive, which compresses the same idea: “Dickens’s novels are longer than Austen” becomes “longer than Austen’s,” where the apostrophe-s carries “novels.” The third tool is the matching construction after “like” or “unlike,” which requires the noun right after it to belong to the same category as the subject of the main clause. Each tool restores the balance; which one you reach for depends on the sentence’s shape.

What is the equal-sign test for comparisons?

Place a mental equal sign between the two things being compared and ask whether the items on each side belong to the same category. If they match, the comparison is logical. If a quantity faces a place, or a thing faces a person, the sentence fails and needs “that of,” “those of,” or a possessive to balance it.

That test is the single most portable tool in this guide, so it deserves a slow walk-through. Take the sentence “The brushstrokes of Van Gogh are more turbulent than Monet.” Find the two things being compared and write them on either side of an imaginary equal sign: “the brushstrokes of Van Gogh” = “Monet.” On the left you have brushstrokes; on the right you have a painter. The equal sign is false, because brushstrokes are not a painter. The repair restores the category: “more turbulent than those of Monet,” where “those” stands in for “the brushstrokes,” giving you brushstrokes = brushstrokes. Now the equal sign holds. The whole diagnosis took the length of a breath, and it never once relied on whether the sentence sounded right.

The test extends cleanly to the “like” and “unlike” constructions, which the exam favors because they hide the comparison at the front of the sentence where readers are not braced for it. “Like the orchestral works of Brahms, the chamber pieces feel architecturally dense” is sound, because orchestral works and chamber pieces are both bodies of music, both compositions. But “Like Brahms, the chamber pieces feel architecturally dense” fails, because Brahms is a person and chamber pieces are compositions. A person cannot be balanced against compositions. The fix names the matching category: “Like the works of Brahms” or “Like other composers, Brahms wrote chamber pieces that feel dense.” The equal sign reveals the mismatch instantly.

One subtlety separates the careful reader from the merely fast one. The category match is about the grammatical thing being compared, not the topic of the sentence. A sentence can be entirely about music and still commit a comparison error, because the error lives in the nouns flanking “than” or “like,” not in the subject matter. Train your eye to land on those flanking nouns and ignore the surrounding content. That discipline, examining the two nouns the comparison joins rather than the sentence’s theme, is what the equal-sign test enforces.

A final mechanical point concerns when you do not need a repair at all. If both sides already hold the same category, leave the sentence alone; adding “that of” where it is not needed creates a different error. “Sales in March exceeded sales in February” is already balanced, sales against sales, and rewriting it as “exceeded that of February” would be wrong because “that” has no singular noun to stand for that the sentence wants repeated. The repair tools are for mismatches, not decorations. Reach for them only when the equal sign fails.

The core investigation: worked examples and the twenty-five-idiom reference

This is the heart of the guide. We will work a graded sequence of examples, the kind the exam actually builds, and then lay out the reference table of the twenty-five idiomatic pairings the assessment tests most. Read the examples as solved problems: the diagnosis, the repair, and the reasoning, narrated rather than listed, so the procedure sinks in. Each one isolates a slightly different flavor of the same two skills.

Worked example one: a quantity compared to a place. The sentence reads, “The gross domestic product of Japan is larger than South Korea.” Apply the equal-sign test. Left side: the gross domestic product of Japan, an economic quantity. Right side: South Korea, a country. Quantity does not equal country, so the comparison is broken. The repair inserts the stand-in: “larger than that of South Korea,” where “that” silently carries “the gross domestic product.” Now quantity faces quantity and the balance holds. The trap here is that “South Korea” feels parallel to “Japan,” so the sentence reads smoothly; but Japan and South Korea are not the things being compared. The product is. Land on the right nouns and the error surfaces.

Worked example two: the possessive repair. Consider, “The poetry of Dickinson is more compressed than Whitman.” The two compared items are Dickinson’s poetry and Whitman, a poet, not Whitman’s poetry. Mismatch. You have two legal repairs. The “that of” form gives “more compressed than that of Whitman.” The possessive form gives “more compressed than Whitman’s,” where the apostrophe-s carries “poetry.” The exam usually offers the possessive as one choice and “that of” as another, and both can be correct; pick whichever the answer set provides without a second error. The possessive is tighter and the test often prefers it, but do not invent a rule that one is always right. The principle is the category match, achieved by either tool.

Worked example three: the “like” construction with a person. The sentence opens, “Like Hemingway, the prose in the later stories grows spare and clipped.” The equal-sign test pairs “Hemingway,” a person, against “the prose,” a body of writing. A person is not prose. The repair supplies the matching category: “Like Hemingway’s prose, the later stories grow spare” or, recasting, “Like Hemingway, the author wrote prose that grows spare.” Notice that the second repair changes the subject of the main clause to a person, “the author,” so that a person now faces a person. Either route restores the balance. The introductory “like” phrase is a favorite hiding spot precisely because the comparison error sits eight words before the reader expects trouble.

Worked example four: two populations, the “those of” form. The sentence states, “The voting patterns of rural counties differ sharply from urban areas.” Compared items: the voting patterns of rural counties versus urban areas. Patterns are not areas, so the equal sign fails. The plural noun “patterns” calls for the plural stand-in: “differ sharply from those of urban areas,” where “those” carries “the voting patterns.” This example also smuggles in an idiom, “differ from,” which is correct; the trap “differ than” would be a second, separate error. Watch for items that braid a comparison flaw and an idiom flaw together, because the exam loves to make you fix both in one choice.

Worked example five: the idiom “different from.” Here is a pure idiom item. “The results of the second trial were no different than the results of the first.” Your ear, trained by conversation, may accept “different than,” but the written standard pairs “different” with “from.” The repair is simply “no different from the results of the first.” There is no comparison-category error here; both sides already hold results. The only flaw is the preposition. This is the cleanest illustration of why the idiom list matters: nothing about the sentence’s logic is wrong, only a memorized pairing, and memory is the only tool that catches it.

Worked example six: the idiom “prohibit from.” The sentence reads, “The new policy prohibits employees to use personal devices during shifts.” The verb “prohibit” takes “from” plus a gerund, never “to” plus an infinitive. The repair is “prohibits employees from using personal devices.” Compare the near-synonym “forbid,” which does take the infinitive (“forbids employees to use”), and you see why the exam tests “prohibit” specifically: the two verbs mean nearly the same thing but govern different structures, and only memory tells them apart. When you meet “prohibit,” the hand should reach automatically for “from” and a gerund.

Worked example seven: the idiom “capable of” versus “capable to.” The sentence states, “The new sensor is capable to detect minute temperature shifts.” The adjective “capable” pairs with “of” plus a gerund: “capable of detecting minute temperature shifts.” The infinitive “capable to detect” is not standard. This pattern, adjective plus “of” plus gerund, recurs across the idiom set, “incapable of,” “guilty of,” “tired of,” and recognizing the family speeds you up. When an adjective is followed by an action, ask whether the standard pairing wants “of” and an -ing verb rather than “to” and a base verb.

Worked example eight: a combined comparison-and-idiom item. The exam’s hardest version fuses both skills. “Unlike the symphonies of Beethoven, Mahler relied on enormous orchestras and required far more capable to sustain long movements.” First, the comparison: “Unlike the symphonies of Beethoven, Mahler” pairs symphonies against a composer, a mismatch; the repair is “Unlike Beethoven, Mahler” so that composer faces composer, or “Unlike the symphonies of Beethoven, those of Mahler” so that symphonies face symphonies. Second, buried later, “more capable to sustain” repeats the idiom error from example seven and wants “capable of sustaining.” A single choice in the answer set will fix both, and only the option that repairs the comparison and the idiom together is correct. These fused items are where the equal-sign test and the idiom list earn their keep at once.

Worked example nine: “comply with.” “Manufacturers must comply to the updated safety standards before the product ships.” The verb “comply” takes “with,” not “to”: “comply with the updated safety standards.” The pull toward “to” comes from the near-synonym “adhere to,” which is itself correct, so the two verbs cross-contaminate in the ear. Hold them apart: you comply with a rule and adhere to a rule, and the exam will test whichever pairing you are likeliest to swap.

Worked example ten: “attribute to.” “Historians attribute the city’s rapid growth on its position along the trade route.” The verb “attribute” pairs with “to”: “attribute the city’s rapid growth to its position.” The wrong preposition “on” feels almost right because “blame on” exists (“blame the growth on its position”), and the two patterns interfere. Sort them: you attribute an effect to a cause, and you blame an effect on a cause. Same idea, different mandated preposition, which is exactly the kind of distinction the assessment rewards you for knowing cold.

Ten worked items establish the two procedures; the reference table below gives you the raw material the idiom items draw from. The exam tests a recurring core of prepositional pairings, and while no list is exhaustive, the twenty-five below cover the constructions that surface most. Treat this as the citable artifact of this guide: the InsightCrunch equal-sign test paired with a twenty-five-idiom reference you can drill until each pairing is automatic.

The twenty-five most-tested SAT idioms

Idiom	Standard preposition	Short usage example
different	from	Her method is different from the standard approach.
prohibit	from	The rule prohibits drivers from parking here.
regard	as	Critics regard the novel as a masterpiece.
responsible	for	The committee is responsible for the budget.
capable	of	The engine is capable of great speed.
succeed	in	She succeeded in persuading the board.
comply	with	Firms must comply with the regulation.
attribute	to	He attributed the delay to bad weather.
debate	over / about	A debate over the proposal continued.
ban	on	The city imposed a ban on fireworks.
preoccupied	with	He was preoccupied with the deadline.
independent	of	The finding is independent of the sample size.
consist	of	The committee consists of nine members.
composed	of	Water is composed of hydrogen and oxygen.
preferable	to	Walking is preferable to driving downtown.
superior	to	The new model is superior to the old one.
native	to	The species is native to the wetlands.
similar	to	Her style is similar to her mentor’s.
opposed	to	Residents were opposed to the rezoning.
insist	on	She insisted on paying the full amount.
rely	on	Farmers rely on seasonal rainfall.
based	on	The film is based on a true account.
centered	on	The discussion centered on funding.
accuse	of	The article accused officials of negligence.
sympathize	with	Readers sympathize with the narrator.

A few entries on that list deserve a closer note because they hide a near-miss the exam exploits. “Centered on” is standard; “centered around” is the common error, since a center is a point and cannot logically sit “around” anything, yet the phrase saturates casual speech. “Preferable to” never takes “than,” even though “prefer” feels comparative; “preferable than” is always wrong. “Independent of” resists the pull toward “independent from,” which sounds plausible but is not the tested standard. And “debate over” or “debate about” are both accepted, so an item testing that idiom will hinge on some other flaw, not on choosing between those two. Knowing where the near-misses live turns the table from a memory chore into a map of the traps.

There is a second tier worth absorbing once the core twenty-five are automatic: “result in” an outcome versus “result from” a cause, “contrast with” rather than “contrast to” in most constructions, “in contrast to” as the set phrase, “agree with” a person but “agree to” a proposal and “agree on” an issue, “devoted to,” “interested in,” “guilty of,” and “blame for” or “blame on.” These extend the same logic, a fixed verb or adjective demanding one specific preposition, and the exam draws from this wider pool on harder forms. The discipline is identical: when a verb or adjective is followed by a preposition, ask whether the standard pairing is the one on the page, and if your only evidence is that it sounds fine, distrust that evidence, because the ear is exactly the faculty these items are built to fool.

More worked comparisons: the patterns beyond the basic mismatch

The first ten examples covered the central category mismatch and the most common idiom slips. The exam builds several further patterns on the same foundation, and working them deliberately closes the remaining gaps. Each pattern below is a real variant you should expect to meet.

Worked example eleven: the incomplete comparison. The sentence reads, “The new battery lasts longer and charges faster.” Longer and faster than what? An incomplete comparison names only one side of the balance and leaves the other implied, which the written standard treats as a flaw when the missing term is genuinely unclear. The repair supplies the second term: “lasts longer and charges faster than the previous model.” The equal-sign test exposes the problem indirectly, because you cannot place anything on the right pan; there is no second item to weigh. When a comparative word like “longer,” “faster,” “more,” or “fewer” appears with no stated point of comparison, ask whether the sentence has told you what the comparison is against, and if it has not, the choice that completes the comparison is usually correct.

Worked example twelve: the “as … as” construction. The sentence states, “Her second novel is as ambitious, if not more ambitious than, her first.” The paired correlative “as … as” must be completed before a different comparative structure takes over, and here “as ambitious” is left dangling without its second “as.” The standard repair completes both structures: “as ambitious as, if not more ambitious than, her first.” This is a comparison error of a structural kind rather than a category kind, and it rewards the reader who notices that “as” opens a frame that must be closed with a matching “as.” The equal-sign test still helps, since both sides hold novels and the categories match; the flaw is the broken correlative frame, not a mismatch of kind.

Worked example thirteen: “compared to” versus “compared with.” The sentence reads, “Compared to last year, enrollment rose by eight percent.” Both “compared to” and “compared with” are accepted in standard usage, with a fine traditional distinction, “compared to” for likeness and “compared with” for measured difference, but the exam rarely hinges an item on that subtlety alone. More often it pairs “compared to” with a buried category mismatch: “Compared to last year, the enrollment figures rose” weighs a year against figures, a mismatch repaired by “Compared to last year’s figures” or “Compared with the figures from last year.” Treat “compared to” as a flag to run the equal-sign test on the two things being set side by side, since the construction so easily smuggles in a mismatch.

Worked example fourteen: comparing amounts with “fewer” and “less.” The sentence states, “The revised plan requires less staff and fewer overhead.” The words “fewer” and “less” are not interchangeable: “fewer” governs countable nouns and “less” governs uncountable ones, so the sentence has them reversed. The repair is “fewer staff and less overhead,” since staff members are countable and overhead is a mass quantity. This pairing sits at the border of comparison and word-choice, and the exam tests it because the ear often defaults to “less” for everything. Whenever a quantity word precedes a noun in a comparison, check whether the noun can be counted, and match “fewer” to countable nouns and “less” to uncountable ones.

Worked example fifteen: the ambiguous comparison resolved by a verb. The sentence reads, “The director praised the lead actor more than the producer.” Two readings compete: the director praised the actor more than the director praised the producer, or more than the producer praised the actor. The first reading is coherent; the second is also coherent but different in meaning. The exam resolves the ambiguity by adding a verb that forces one reading: “more than the producer did” makes the producer a second praiser, while “more than he did the producer” makes the producer a second object of praise. When a comparison could attach to two different things, the correct choice is the one that disambiguates, usually by supplying the missing verb. The category match holds in both readings, so the flaw here is clarity rather than logic.

Worked example sixteen: “regard as” and the missing preposition. The sentence states, “Many economists regard the policy a failure.” The verb “regard” requires “as”: “regard the policy as a failure.” Dropping the “as” is a common error because the near-synonym “consider” takes no preposition at all (“consider the policy a failure” is standard). The two verbs mean nearly the same thing and govern different structures, so the exam tests “regard” to catch students who borrow the “consider” pattern. When you see “regard,” supply “as” automatically, and when you see “consider,” expect no preposition. This is another instance of near-synonym interference, the single most productive source of idiom items on the whole assessment.

Worked example seventeen: “responsible for” and “responsible to.” The sentence reads, “The new manager is responsible to overseeing three departments.” The adjective “responsible” takes “for” plus a gerund when naming a duty: “responsible for overseeing three departments.” The form “responsible to” exists but means accountable to a person (“responsible to the board”), a different sense, so the exam tests whether you know which preposition matches which meaning. When “responsible” introduces a task or duty, the pairing is “for” plus an -ing verb; when it introduces a person or authority one answers to, the pairing is “to.” Reading the meaning tells you which preposition the standard wants, but only because you have stored both pairings in advance.

Worked example eighteen: a fused triple, comparison plus two idioms. The hardest items stack errors. “Unlike the early paintings of Rothko, the later canvases were composed from larger fields of color and were superior than the works that preceded them.” Three flaws hide here: the comparison pairs paintings against canvases, which actually matches in category, so that opening is sound; “composed from” should be “composed of”; and “superior than” should be “superior to.” The correct choice repairs both idioms while leaving the sound comparison intact. This example teaches a final discipline: do not assume every comparison word signals an error, and do not assume every preposition is wrong. Run each test, confirm or clear each potential flaw, and select the choice that fixes the genuine errors without disturbing what was already correct.

These eight further patterns, added to the first ten, give you eighteen worked items spanning every common form: the quantity-to-place mismatch, the possessive repair, the “like” and “unlike” constructions, the population comparison, the incomplete comparison, the “as … as” frame, the ambiguous comparison, the “fewer” and “less” distinction, and idiom corrections across “different,” “prohibit,” “capable,” “comply,” “attribute,” “regard,” “responsible,” “composed,” and “superior.” Working them until the diagnosis is automatic is the surest preparation for this corner of the Writing content.

The idiom families in depth

The twenty-five-idiom table is a reference, but idioms become easier to retain when you see them grouped by the family they belong to, because the families share a structure and a logic. There are three broad families, and a handful of cross-cutting traps that the exam exploits across all of them.

The first family is the verb-plus-preposition pairing, where a verb fixes a particular preposition that introduces its object or complement. “Comply with,” “attribute to,” “prohibit from,” “succeed in,” “insist on,” “rely on,” “accuse of,” and “sympathize with” all belong here. The defining trap in this family is near-synonym interference: a verb close in meaning takes a different preposition, so the ear borrows the wrong one. “Comply with” sits beside “adhere to”; “attribute to” sits beside “blame on”; “prohibit from” sits beside “forbid to”; “regard as” sits beside “consider” with no preposition at all. The discipline is to store each verb with its own preposition and to be especially wary when a verb has a familiar cousin, because the cousin is exactly what the wrong answer borrows from.

The second family is the adjective-plus-preposition pairing, where an adjective demands a specific preposition before its complement. “Different from,” “capable of,” “responsible for,” “independent of,” “preferable to,” “superior to,” “native to,” “similar to,” “opposed to,” and “preoccupied with” populate this group. A recurring trap here is the comparative-feeling adjective that resists “than”: “preferable” and “superior” both carry a sense of comparison, so the ear wants “preferable than” and “superior than,” yet the standard fixes both to “to.” Another trap is the adjective that pairs with “of” plus a gerund when an action follows, as in “capable of detecting” rather than “capable to detect.” Grouping the adjectives this way, and noting which ones reject “than” and which ones want “of” plus an -ing verb, turns a scattered list into a small set of patterns.

The third family is the noun-plus-preposition pairing, where a noun governs the preposition that follows it. “A ban on,” “a debate over” or “about,” “a preoccupation with,” “an attribute of,” and “a contrast with” or “in contrast to” belong here. Nouns formed from verbs often keep a preposition related to the verb’s, so “a reliance on” follows “rely on” and “an insistence on” follows “insist on,” which gives you a way to reason from the verb to the noun within a single root. The trap in this family is that the noun form sometimes shifts the preposition slightly from the verb form, so “different from” as an adjective pairs with “a difference between” or “a difference from” as a noun depending on the construction, and the exam tests whether you track the shift.

Across all three families runs a single cross-cutting trap that deserves its own mention: the gerund-versus-infinitive choice after the preposition. Once a verb or adjective has fixed its preposition, an action that follows usually takes the gerund, the -ing form, not the infinitive. “Capable of detecting,” “prohibited from parking,” “succeeded in persuading,” “responsible for overseeing,” and “insisted on paying” all use the gerund because a preposition governs them, and a preposition is followed by a noun or a gerund, never by an infinitive. The error “capable to detect,” “prohibited to park,” “succeeded to persuade” substitutes the infinitive and is reliably wrong. This single rule, that a preposition takes a gerund rather than an infinitive, resolves a large share of the harder idiom items at a stroke, because the exam loves to pair the right preposition with the wrong following verb form to see whether you notice.

A short tour of the second-tier pairings rounds out the families. “Result in” introduces an outcome (“the delay resulted in higher costs”), while “result from” introduces a cause (“the higher costs resulted from the delay”), and the exam tests whether you can tell the effect direction from the preposition. “Agree with” applies to a person (“I agree with her”), “agree to” applies to a proposal (“they agreed to the terms”), and “agree on” applies to a shared issue (“the parties agreed on a date”), three prepositions for one verb sorted by what follows it. “Contrast with” is the usual verb pairing (“the result contrasts with the prediction”), while “in contrast to” is the set phrase that opens a sentence. “Devoted to,” “interested in,” “guilty of,” “tired of,” and “capable of” extend the adjective family, each fixed by convention. None of these can be derived from meaning, which is why even the second tier rewards drilling rather than reasoning.

The practical upshot of grouping idioms into families is retention. A flat list of twenty-five pairings is hard to hold; three families with shared structures and a single gerund rule are far easier, because you are storing patterns rather than isolated facts. When an idiom item appears, identify the family first, verb, adjective, or noun, then recall the family’s standard preposition and check whether an action that follows wants the gerund. That two-step recall is faster and more reliable than scanning a memorized list item by item, and it scales to the second-tier pairings the harder routing draws on.

A worked walkthrough of attacking the four choices

Strategy becomes concrete when you watch it run on a full item, so here is the procedure applied end to end. Suppose the question underlines a stretch of this sentence: “The migratory range of the arctic tern is far greater than the albatross, a bird often assumed to travel the longest distances.” The four choices offer “than the albatross,” “than that of the albatross,” “than the albatross’s,” and “than those of the albatross.”

Step one is to name the family. The sentence contains “than,” so this is a comparison, and you run the equal-sign test. The two compared items are “the migratory range of the arctic tern” and whatever follows “than.” Range is a singular quantity, so the right pan must hold a range, not a bird.

Step two is to test each choice against that diagnosis. “Than the albatross” pairs range against a bird, a category mismatch, so it is out. “Than those of the albatross” uses the plural stand-in “those,” but the noun being replaced, “range,” is singular, so the number disagrees and it is out. That leaves “than that of the albatross,” where singular “that” carries “range,” and “than the albatross’s,” where the possessive carries “range.” Both balance the equal sign and both are grammatical.

Step three is to find the discriminator between the two survivors, because the exam will not present two fully correct answers. Reread both in context. “Greater than that of the albatross” is clean. “Greater than the albatross’s” is also clean, but the surrounding sentence and the answer set will usually tilt toward one; if the test intends the explicit stand-in, “that of” is the keyed answer, and if it intends compression, the possessive is. When two repairs are genuinely equal, look for a buried second error in one of them, an idiom or agreement slip, that the exam has planted to break the tie. The correct choice is the one that balances the comparison and carries no second flaw.

This three-step run, name the family, test each choice against the single diagnostic, then discriminate between survivors, is the same procedure for every comparison and idiom item, and it is fast because it never asks you to read the choices holistically. You are not searching for the option that sounds best; you are eliminating the options that fail one precise test. Practiced to reflex, the whole walkthrough takes under thirty seconds, which is exactly the speed that turns these items into the time bank the rest of the section needs.

Worked corrections across the remaining high-frequency pairings

To make every entry in the reference table a recognized face rather than a name on a list, here are short worked corrections for the pairings the first eighteen examples did not yet exercise. Each follows the same shape: the flawed version, the standard repair, and the reason the error tempts the ear.

The verb “succeed” takes “in” plus a gerund. “After months of lobbying, the coalition succeeded to pass the measure” should read “succeeded in passing the measure.” The infinitive tempts because “managed to pass” is standard and “manage” and “succeed” feel interchangeable, but the prepositions diverge. The verb “insist” takes “on” plus a gerund or noun. “The auditor insisted to review every transaction” should read “insisted on reviewing every transaction.” The pull toward the infinitive comes from “demanded to review,” where “demand” does take the infinitive, another near-synonym crossover.

The verb “rely” takes “on” or “upon.” “Coastal towns rely in tourism for most of their income” should read “rely on tourism.” The wrong preposition “in” intrudes because “invest in” and “trade in” sit nearby in the economic vocabulary, priming the ear. The adjective “native” takes “to.” “The kangaroo is native of Australia” should read “native to Australia.” The error “native of” appears because “a native of Australia,” using “native” as a noun, is correct, so the adjective borrows the noun’s preposition. Meaning and part of speech together fix the standard, but only memory tells you which one the sentence is using.

The adjective “opposed” takes “to.” “The council was opposed against the new levy” should read “opposed to the new levy.” The redundant “against” creeps in because “against” already carries opposition, so the ear doubles the idea. The verb “sympathize” takes “with.” “Readers tend to sympathize for the narrator” should read “sympathize with the narrator.” The error “sympathize for” borrows from “feel sympathy for,” where the noun form does take “for,” another verb-versus-noun crossover within a single root.

The verb “accuse” takes “of” plus a gerund or noun. “The report accused the agency for ignoring the warnings” should read “accused the agency of ignoring the warnings.” The wrong “for” comes from “blamed the agency for,” since “blame” takes “for” and “accuse” takes “of,” two close verbs with different prepositions. The adjective “preoccupied” takes “with.” “Throughout the spring she was preoccupied by the upcoming defense” can stand in some registers, but the tested standard is “preoccupied with the upcoming defense,” and the exam keys “with.”

The adjective “independent” takes “of.” “The result proved independent from the sample size” should read “independent of the sample size.” The error “independent from” sounds plausible because “free from” and “separate from” sit nearby, but the standard fixes “independent” to “of.” The verb “consist” takes “of.” “The panel consists in five experts” should read “consists of five experts,” since “consist in” exists but means something different (“happiness consists in contentment,” meaning is found in), a sense the exam can exploit by offering “consist in” where “consist of” belongs.

Finally, the noun “ban” takes “on” and the noun “debate” takes “over” or “about.” “The legislature imposed a ban against single-use plastics” should read “a ban on single-use plastics,” and “a debate around the proposal” is better as “a debate over the proposal” or “a debate about the proposal,” though “around” has crept into casual use. Working these remaining pairings alongside the earlier eighteen examples means every entry in the reference table now has a face, a flaw, and a repair attached, which is the condition under which the pairing fires automatically on test day.

A diagnostic error-category rubric

When you review practice items, sorting your misses into categories tells you where the preparation should go, so here is a rubric that classifies every comparison and idiom error into a small set of types. Use it to label each item you get wrong, then drill the category that recurs.

The first category is the category mismatch, the classic faulty comparison, where the two compared nouns belong to different kinds. The signal is “than,” “as,” “like,” or “unlike” joining a quantity to a place, a thing to a person, or a body of work to its creator. The repair tool is “that of,” “those of,” or a possessive. If your misses cluster here, drill the equal-sign test until landing on the two flanking nouns is automatic.

The second category is the incomplete or ambiguous comparison, where the second term of the comparison is missing or where the comparison could attach to two different things. The signal is a comparative word with no stated point of comparison, or a comparison that admits two readings. The repair supplies the missing term or adds a disambiguating verb. If your misses cluster here, practice asking “compared to what, exactly” on every comparative word.

The third category is the structural comparison flaw, where a correlative frame like “as … as” is broken or where “fewer” and “less” are swapped. The signal is a half-finished “as” frame or a quantity word that does not match the countability of its noun. The repair completes the frame or matches the quantity word to the noun. If your misses cluster here, review the “as … as” construction and the “fewer” versus “less” rule specifically.

The fourth category is the verb-plus-preposition idiom, where a verb takes the wrong preposition. The signal is a verb followed by a preposition that does not match the stored pairing, often because a near-synonym takes a different one. The repair substitutes the standard preposition. If your misses cluster here, drill the verb family of the reference table and pay special attention to the near-synonym crossovers, comply with versus adhere to, attribute to versus blame on, regard as versus consider.

The fifth category is the adjective-plus-preposition idiom, where an adjective takes the wrong preposition, including the comparative-feeling adjectives that wrongly attract “than.” The signal is an adjective followed by a nonstandard preposition, especially “superior than,” “preferable than,” or “independent from.” The repair substitutes the standard preposition. If your misses cluster here, drill the adjective family and memorize which adjectives reject “than.”

The sixth category is the gerund-versus-infinitive error after a preposition, where the right preposition is followed by the wrong verb form. The signal is a correct preposition trailed by an infinitive, “capable to detect,” “prohibited to enter,” where the standard wants the gerund. The repair converts the infinitive to the -ing form. If your misses cluster here, internalize the single rule that a preposition takes a gerund, never an infinitive.

Labeling each missed item with one of these six categories turns vague underperformance into a targeted plan. Two or three review sessions with the rubric usually reveal that your errors concentrate in one or two categories rather than scattering evenly, and concentrating your drilling on those categories raises accuracy faster than reviewing everything equally. The rubric is itself a findable artifact you can carry into any practice set: six labels, one diagnosis each, one repair each.

Building the skill before test day

The preparation timeline for these two skills is short relative to reading stamina or math fluency, which is part of why they reward late-stage attention from a student running short on weeks. Begin by converting the twenty-five-idiom table into flashcards, with the verb or adjective on one side and the standard preposition plus a one-line example on the other, and run them daily until each pairing fires before you finish reading the prompt word. Layer in the second-tier pairings once the core is automatic. Flashcards suit idioms perfectly because the knowledge is atomic, a fact per card, with no reasoning to slow the recall.

For comparisons, the drill is different because the skill is procedural rather than factual. Work mixed sets of comparison items and force yourself to run the equal-sign test aloud or on paper for each one, naming the two compared nouns explicitly before choosing an answer. The goal is to make the procedure so habitual that you run it silently and instantly during the exam. Pair this with the rubric, labeling every miss by category, so that your practice is diagnostic rather than merely repetitive. A practice session that ends with a labeled list of your error categories teaches more than one that ends with a raw score.

Realistic rehearsal under timed conditions is the final and most important phase, because the skills must work at speed and under the mild pressure of the clock, not just in untimed review. Drilling comparison and idiom items in an interface that mirrors the digital format and supplies immediate worked solutions lets you confirm each diagnosis the instant you commit, which is the feedback loop that converts a rule you know into a reflex you trust. Spacing this rehearsal across several short sessions beats cramming it into one long block, since the spacing strengthens recall and the variety of items in each session keeps the procedures sharp. Read the rule once, drill the pairings daily, rehearse mixed items under time, and label every miss; that sequence is the whole preparation, and it is short enough to complete in the final weeks before the exam.

The deeper habit you are building is editorial rather than merely test-specific. Every time you correct a “different than” to a “different from,” or balance a faulty comparison with “that of,” you are practicing the act of editing your own language against a standard, choosing the rule over the reflex. That habit outlasts the exam and serves any writing you do afterward, which is the quiet argument for treating these small items as worth real attention rather than as trivia. The points are the immediate reward; the editorial eye is the lasting one.

Pronoun case in elliptical comparisons

A comparison family the exam tests quietly involves the case of a pronoun after “than” or “as,” and it rewards a small piece of reasoning rather than memorization. When a comparison trails off after the pronoun, the sentence is elliptical, meaning a verb is understood but not written, and the case of the pronoun depends on the verb the reader is meant to supply. “My brother is taller than I” is standard because the full thought is “taller than I am,” where “I” is the subject of the implied “am.” Replacing it with “taller than me” changes the implied structure and, under the tested standard, is treated as the error in such items.

The reasoning becomes clearer when the two readings produce genuinely different meanings, which is where the exam plants its harder version. “She trusts the new analyst more than I” completes to “more than I trust the new analyst,” making “I” a second truster, while “She trusts the new analyst more than me” completes to “more than she trusts me,” making “me” a second object of trust. Both are grammatical, but they say different things, and the correct choice is the one whose pronoun case matches the intended meaning. To resolve such an item, mentally finish the elliptical clause with the understood verb and ask whether the pronoun is doing the action (subject case, “I,” “he,” “she,” “they”) or receiving it (object case, “me,” “him,” “her,” “them”). The case you need is the one the completed clause demands.

This pattern sits at the intersection of comparison and pronoun usage, so it draws on the same clarity discipline as the ambiguous comparisons worked earlier, and it pairs naturally with the broader pronoun-clarity skills the conventions content tests. The practical move is to treat any pronoun immediately after “than” or “as” as a flag: complete the implied clause, identify the pronoun’s role, and choose the case that role requires. Because conversational English overwhelmingly favors the object form, “taller than me,” your ear will usually push you toward the wrong answer on these items, which is exactly why the exam includes them. The defense, once more, is to run a quick test rather than to trust the comfortable form, completing the clause in your head and letting the recovered verb decide the case.

A related quantity comparison uses “as much as” and “as many as,” and the same countability rule from “fewer” and “less” applies: “as many” governs countable nouns and “as much” governs uncountable ones. “The new reservoir holds as much gallons as the old one” should read “as many gallons,” since gallons are countable, while “The new policy generated as many controversy” should read “as much controversy,” since controversy is uncountable. These items braid the correlative “as … as” frame with the countability distinction, so they reward a reader who checks both that the frame is complete and that the quantity word matches the noun. When a comparison uses “as much” or “as many,” confirm the noun’s countability before accepting the choice, because the ear defaults inconsistently between the two forms.

Taken together, the pronoun-case and quantity-comparison patterns extend the comparison family beyond the core category mismatch into the finer structural choices the exam uses to separate strong test-takers from very strong ones. None of them requires new memorization; each requires the same habit the equal-sign test instills, which is to complete the comparison in full, examine the precise elements it joins, and let the recovered structure rather than the comfortable sound decide the answer. The comparison skill, fully developed, is this single habit applied across every form the sentence can take.

Strategy and application: turning the rules into points

Knowing the equal-sign test and the idiom list is necessary but not sufficient; the points come from a procedure you run the same way every time, fast enough to leave room for the reading-heavy items. The first move on any conventions question that involves a comparison or a preposition is to identify which family you are in. If the sentence contains “than,” “as,” “like,” or “unlike,” suspect a comparison and run the equal-sign test. If the sentence pairs a verb or an adjective with a preposition, suspect an idiom and check the pairing against your memorized set. Naming the family before you evaluate the choices is what keeps you from reading the four options four times.

Once you have named the family, attack the choices through the lens of that single diagnosis rather than reading each one as a fresh sentence. For a comparison item, you are not asking “which choice sounds best”; you are asking “which choice makes the two compared things match in category.” Three of the four options will leave the mismatch in place or introduce a new error, and the right one will balance the equal sign. For an idiom item, you are asking “which choice uses the standard preposition,” and the answer is the one whose pairing matches your list. This is a process of targeted elimination, not holistic judgment, and targeted elimination is both faster and more reliable.

A practical rule governs the order of attack within a module. Comparison and idiom items are among the quickest conventions questions to resolve once diagnosed, so treat them as time banks. Resolve them decisively, do not second-guess a clean diagnosis, and carry the saved seconds into the rhetoric and reading-comprehension items that genuinely require slow rereading. The student who lingers on a comparison item, rereading all four choices in search of a feeling of rightness, is spending the very time the item was designed to give back. Diagnose, repair, move.

How should I pace a comparison or idiom item?

Aim to spend under thirty seconds. Name the family first, comparison or idiom, then apply the matching tool: the equal-sign test or the memorized pairing. Eliminate the three choices that fail the single diagnostic, confirm the survivor introduces no new error, and move on without rereading for a feeling of correctness.

The single most useful habit for these items is learning to distrust fluency. The whole reason comparisons and idioms are tested is that the wrong answer reads smoothly. “Different than” flows. Comparing a city to a city’s rival feels parallel. Your fluency is the symptom, not the cure, because the choices were engineered to exploit it. The trained response is to notice that a choice sounds fine and then deliberately run the test anyway, treating smoothness as a reason to check rather than a reason to relax. This inversion, where ease becomes a warning rather than a green light, is the strategic core of the whole topic.

For the idiom items specifically, the strategy is mostly preparation rather than in-the-moment technique, because you cannot derive a fixed preposition from logic; you either know it or you guess. That is why the reference table earns daily drilling in the weeks before the exam. Convert the table into flashcards, verb or adjective on one side, mandated preposition and a sample sentence on the other, and run them until the pairing fires automatically. The goal is to reach a state where “prohibit” pulls “from” without a pause and “comply” pulls “with” before you have finished reading the verb. Idiom items reward stored knowledge, so build the store.

Rehearsal beats reading, which is why moving from worked examples to live practice is the step that actually converts these procedures into points. After you have absorbed the equal-sign test and the idiom set, the most efficient next action is to drill comparison and idiom items in a realistic interface with immediate feedback, so you can see whether your diagnosis was right the instant you commit to it; the SAT Reading and Writing practice tool at ReportMedic gives you section-targeted conventions questions with full worked solutions, which is exactly the rehearsal loop that turns a memorized rule into an automatic reflex. Read a rule once, then rehearse it ten times; the rehearsal is where the point is won.

Two interface habits help on test day. First, when a comparison choice offers both “that of” and a possessive form as separate options, and both would be grammatical, look for a second discriminator, a subtle idiom or agreement flaw, because the exam will not present two fully correct answers; one of them carries a hidden second error. Second, on idiom items, read the preposition before you read the rest of the choice, since the preposition is the whole question and the surrounding words are camouflage. Training your eye to land on the operative word first saves a reread on every item in the family.

Edge cases and the harder end

The Module 2 versions of these items raise the difficulty in predictable ways, and knowing the harder forms ahead of time keeps them from surprising you. The most demanding comparison items bury the mismatch inside a long, clause-heavy sentence so that the two compared nouns sit far apart, separated by modifiers and subordinate clauses that wear down your attention before you reach the second noun. The defense is mechanical: regardless of the distance, find the two things the comparison joins, lift them out of the surrounding clutter, and set them on either side of the equal sign. Distance is the only added difficulty; the test itself does not change.

A second hard variant uses an ambiguous comparison, where the sentence could logically compare two different pairs of things and the wrong reading produces a category error while the right reading does not. “The committee admired the design of the new wing more than the architect” can mean the committee admired the design more than it admired the architect, or more than the architect admired the design. The first reading compares a design to a person, a mismatch, while the second is coherent. The exam resolves such ambiguity by offering a choice that disambiguates, often by adding a verb, “more than the architect did,” which forces the coherent reading. When a comparison feels slippery, suspect an ambiguity the right answer is built to clear up.

Why do harder comparison items separate the compared nouns?

Distance erodes attention. By placing modifiers and subordinate clauses between the two nouns a comparison joins, the harder items make you forget the first noun’s category before you reach the second. The fix is to pull both nouns out of the sentence and test them against each other directly, ignoring everything in between.

The idiom items grow harder in two ways. The first is by testing the lower-frequency pairings, the second-tier set of “result from,” “contrast with,” “agree on,” and the like, where even prepared students have thinner memory. The second is by embedding the idiom inside a phrase that supplies a competing preposition nearby, so that the surrounding context nudges you toward the wrong choice. “In her response to the criticism, she complied to every demand” floats “to” twice before the tested verb, priming your ear to accept “complied to” when the standard is “complied with.” The defense is to isolate the tested verb and its preposition from the surrounding prepositions, evaluating the pairing on its own rather than letting the sentence’s other prepositions vote.

A genuinely tricky edge case sits at the boundary between a comparison and a parallelism error, and distinguishing them matters because the repairs differ. A comparison error is about the category of the two compared nouns; a parallelism error is about the grammatical form of items in a series or on two sides of a coordinating structure. “Running on the trail is healthier than to swim in the lake” is a parallelism flaw, mismatched forms, “running” against “to swim,” fixed by “than swimming in the lake,” not a category mismatch. The two error families look adjacent and sometimes co-occur, but the equal-sign test diagnoses category, while parallelism asks about form. For the full treatment of the form question, the dedicated guide to parallel structure and modifier placement works the matching-form skill in depth, and keeping the two diagnostics separate, category versus form, prevents you from applying the wrong repair under time pressure.

One more edge case rewards attention: the comparison that is logically sound but stylistically redundant, where the exam offers a tighter choice that conveys the same balanced comparison in fewer words. “The enrollment at the larger campus exceeded the enrollment at the smaller campus” is correct but heavy; a choice reading “exceeded that at the smaller campus” trims the repetition while keeping the equal sign intact. When every choice is grammatical, the exam’s preference for concision becomes the discriminator, and the leanest option that preserves the logical comparison is usually the intended answer. Concision is a tiebreaker, never a license to break the category match.

Wider significance: how these skills connect to the whole exam

Comparisons and idioms are small in footprint but large in what they reveal about how the Writing content is built. Both belong to the rule-governed conventions family, and that family rewards a particular temperament: the student who replaces “what feels right” with “what the rule says” gains points across every conventions question, not just these two. Mastering the equal-sign test and the idiom set is therefore a rehearsal for the whole conventions approach, which is why students who internalize these procedures often see their accuracy rise on subject-verb agreement, pronoun clarity, and punctuation at the same time. The transferable skill is the habit of diagnosing before deciding.

That habit pays a second dividend in the reading-comprehension items, where logical comparison reappears in disguise. Command-of-evidence and inference questions frequently ask you to compare claims, weigh one piece of data against another, or judge whether two ideas are genuinely parallel, and the same discipline that catches a faulty comparison in a grammar item, asking whether two things truly match in kind, sharpens your reading of arguments. The student who can see that a passage compares a quantity to a place, or that an author’s analogy pairs two non-matching categories, reads more critically than one who takes every comparison at face value. The conventions skill and the comprehension skill share a root.

The idiom set, meanwhile, connects to vocabulary and to the broader payoff of reading widely. The prepositions English fixes to its verbs and adjectives are not random; they are the residue of how the language evolved, and a reader who has absorbed a great deal of standard written prose tends to have many of these pairings already stored, simply from exposure. Drilling the table is the fast path, but the durable path is reading, because reading installs the pairings alongside everything else it teaches. A student building toward a high Writing score benefits from both the targeted list and the wide reading that makes the list feel like recognition rather than memorization.

There is an admissions dimension as well. The Writing content contributes to the Reading and Writing score, which combines with Math for the total that colleges see, and conventions accuracy is one of the most reliably improvable components of that score because it rests on finite, learnable rules rather than on the slower-growing skills of reading speed and stamina. A student short on time before the exam can raise a conventions subscore faster than almost any other single area, and comparisons and idioms, being rule-based and list-based, are among the fastest of the fast. For the strategic picture of how conventions accuracy fits a target score and where the points are most efficiently won, the grammar conventions reference maps the full set of rule-governed items and their relative weight, while the broader grammar rules guide situates these skills within the writing fundamentals every test-taker needs.

There is also a comparative-exam angle worth noting for students weighing more than one path. The discipline of comparing like to like and of choosing the conventional preposition is not unique to one assessment; the writing portions of the ACT test the same logical-comparison and idiom families, so the equal-sign test and the reference table transfer directly to that exam for students sitting both. Readers mapping a fuller testing plan can see how the rule-governed writing skills line up across formats through the broader grammar reference, since the underlying standard, edited written English, is shared rather than test-specific. A student who builds the editorial habit here is building it for every standardized writing measure at once, which makes the hours spent on these two skills among the most portable in the entire preparation. The same can be said for university-level placement writing and for the editing demanded in first-year composition, where the standard tested here remains the working baseline.

Seen from a distance, the deeper lesson of comparisons and idioms is about the relationship between speech and the written standard. The exam is, in part, a test of whether you can edit the language rather than merely speak it, and editing means knowing where the standard diverges from the comfortable. Every “different from” you correct, every faulty comparison you balance, is a small act of editing, a moment of choosing the rule over the reflex. That capacity, the ability to override fluency with a learned standard, is what the conventions content measures, and it is a capacity that serves a writer long after the exam is over.

Common mistakes and myths corrected

The most damaging mistake is trusting the ear, and it deserves naming first because it underlies nearly every wrong answer on these items. Students assume that a sentence which sounds fine is fine, but conversation is a permissive editor that tolerates “different than,” accepts comparisons between mismatched categories, and lets prepositions slide. The exam is built on exactly the gap between what speech permits and what the written standard requires. The correction is to treat fluency as a prompt to check rather than a verdict, and to run the equal-sign test or consult the idiom list even, especially, when the sentence sounds perfectly natural.

A second, more specific mistake is believing that “different than” is acceptable because everyone says it. In standard written English of the kind tested here, “different” pairs with “from,” full stop. “Different than” appears in casual American speech constantly, which is precisely why the exam tests it; the frequency of the error in conversation is the source of its difficulty on the page. The same applies to “centered around,” which the ear accepts and the standard rejects in favor of “centered on,” and to “preferable than,” which feels comparative but must be “preferable to.” These are not arbitrary preferences; they are the tested standard, and knowing them is worth real points.

A third myth holds that comparison errors are about the subject matter of the sentence, so that a sentence about cities must be comparing cities and a sentence about authors must be comparing authors. The error lives in the nouns flanking the comparison word, not in the topic. A sentence can be entirely about literature and still compare a body of work to a person, because the flaw is grammatical, located in the two nouns the comparison joins, not thematic. Students who scan for the topic instead of the flanking nouns miss the mismatch every time. Land on the nouns beside “than,” “as,” “like,” or “unlike,” and ignore what the sentence is broadly about.

A fourth mistake is over-applying the repair tools, inserting “that of” or “those of” into comparisons that are already balanced. “Sales rose faster than profits” needs no repair, because sales and profits are both quantities and the equal sign already holds; forcing “faster than that of profits” introduces an error by giving “that” no clear noun to carry. The repair tools exist for mismatches, not for every comparison. The test is to apply a fix only after the equal-sign test has actually failed, never as a reflex whenever a comparison appears.

A fifth and subtler error is confusing a comparison flaw with a parallelism flaw and reaching for the wrong repair. When two sides of a comparison differ in grammatical form rather than in category, the issue is parallelism, fixed by matching the form, not by inserting “that of.” “She prefers hiking to a swim” mismatches a gerund with a noun phrase and wants “hiking to swimming,” a parallelism repair, not a category repair. The two families sit close together and sometimes appear in the same item, but the diagnosis differs, and applying the comparison repair to a parallelism problem leaves the real flaw untouched. Separate the questions: is the category mismatched, or is the form mismatched? The answer tells you which tool to use.

A final myth concerns the idioms specifically: that you can reason your way to the right preposition from the meaning of the words. You cannot, reliably. “Comply with” and “adhere to” mean nearly the same thing yet take different prepositions; “attribute to” and “blame on” share a logic yet diverge; “capable of” and “able to” are near-synonyms with different structures. The prepositions are fixed by convention, not derivable from meaning, which is why the idiom set must be memorized rather than reasoned out. Students who try to logic their way to the preposition will be right just often enough to feel justified and wrong often enough to lose points. Store the pairings; do not derive them.

Closing direction

The rainfall sentence we opened with, “greater than Phoenix,” looked finished and was broken, and you can now see exactly why and exactly how to fix it: the equal sign between “rainfall” and “Phoenix” is false, and “that of Phoenix” restores it. That is the whole skill in miniature. Two questions, asked deliberately on every relevant item, carry the entire topic: can I draw an equal sign between the two things being compared, and is this the standard preposition for this verb or adjective? The first question is logic you can run on any sentence; the second is memory you can build from the table above.

Your next action is concrete. Take the twenty-five-idiom table, convert it to flashcards, and drill it until each pairing fires without a pause, then run a set of mixed comparison and idiom items under timed conditions so the equal-sign test becomes a reflex rather than a deliberate step. Practice the diagnosis until naming the family, comparison or idiom, happens the instant you see “than” or a verb-plus-preposition, because the speed is where the saved time lives. A rule you have read is worth little; a rule you have rehearsed into reflex is worth a point on every item it touches.

Trust the rule over the reflex, and the items that once slipped past you on a wave of fluency become the fastest points in the section. The ear got you this far in life; the standard gets you the score. Learn where they diverge, and you will never again read “different than” without your hand reaching, automatically, for “from.”

Frequently Asked Questions

What is a logical comparison error on the SAT?

A logical comparison error occurs when a sentence compares two things that belong to different categories, such as a quantity and a place or a person’s work and the person. The grammar may be flawless and the words correctly spelled, yet the comparison is broken because the two sides of “than,” “as,” “like,” or “unlike” hold mismatched kinds of things. A sentence reading “The population of Brazil is larger than Argentina” compares a population to a country, which is illogical; the population should be compared to another population. These errors are tested under Standard English Conventions because they are rule-governed and detectable with a procedure rather than a feeling. The reliable repair inserts a stand-in such as “that of” or “those of,” or uses a possessive, so that the two compared items match in category. The trap is that the broken sentence usually sounds natural, since everyday speech tolerates these mismatches, which is exactly why the assessment includes them.

What is the equal-sign test for comparisons?

The equal-sign test is a quick diagnostic for any comparison: place a mental equal sign between the two things being compared and ask whether the items on each side belong to the same category. If a quantity faces a quantity, or a person faces a person, or one body of work faces another body of work, the comparison is logical and the sentence stands. If a quantity faces a place, or a thing faces a person, the equal sign is false and the sentence needs repair. For “The brushstrokes of Van Gogh are bolder than Monet,” the test pairs brushstrokes against a painter, a mismatch, so you insert “those of” to get “bolder than those of Monet.” The power of the test is that it ignores how the sentence sounds and focuses only on the two nouns the comparison joins, which is precisely where the error lives. Run it on every item containing “than,” “as,” “like,” or “unlike,” and you will catch the category mismatch in seconds without relying on instinct.

Is it “different from” or “different than” on the SAT?

It is “different from.” In standard written English of the kind the exam tests, the adjective “different” pairs with the preposition “from,” and “different than” is treated as an error even though it appears constantly in casual American speech. A sentence reading “The second draft was no different than the first” must be corrected to “no different from the first.” The frequency of “different than” in conversation is exactly why the assessment tests it: your ear has been trained to accept the nonstandard form, so the item is designed to catch you trusting that training. When you see “different” followed by a preposition, the correct pairing is always “from,” and the appearance of “than” after “different” is a reliable signal that the choice is wrong. Store this pairing as one of the most heavily tested idioms in the set and let it fire automatically whenever “different” appears.

How do I fix a comparison between unlike things?

You restore the category match using one of three repair tools. The first is “that of” for a singular noun or “those of” for a plural noun, which inserts a stand-in for the repeated noun: “The climate of Norway is milder than that of Russia” balances climate against climate. The second is the possessive, which compresses the same idea: “Dickens’s novels are longer than Austen’s” lets the apostrophe-s carry “novels.” The third applies to “like” and “unlike” constructions and requires the noun right after them to match the subject’s category: “Like Hemingway’s prose, the later stories grow spare” pairs prose against stories. Choose the tool that fits the sentence’s shape and that the answer choices offer; both “that of” and the possessive are often correct, so pick whichever the option set provides without a second error. Apply a repair only after the equal-sign test has actually failed, never as a reflex, because forcing a fix onto an already-balanced comparison introduces a new error.

Which prepositions does the SAT test most in idioms?

The most heavily tested prepositions cluster around a recurring core of verb and adjective pairings. “From” appears with “different” and “prohibit”; “of” appears with “capable,” “consist,” “composed,” “independent,” and “accuse”; “to” appears with “attribute,” “preferable,” “superior,” “native,” “similar,” and “opposed”; “with” appears with “comply,” “preoccupied,” and “sympathize”; “on” appears with “rely,” “based,” “insist,” “centered,” and “ban”; “as” appears with “regard”; “for” appears with “responsible”; and “in” appears with “succeed.” The exam favors pairings where a near-synonym takes a different preposition, such as “comply with” beside “adhere to,” or “attribute to” beside “blame on,” because those crossovers are where memory fails. There is no way to derive these pairings from the meanings of the words, so they must be memorized. Drilling the twenty-five-idiom reference table until each pairing fires automatically is the single most efficient preparation for the idiom items, since they reward stored knowledge rather than in-the-moment reasoning.

When do I use “that of” versus a possessive in a comparison?

Both repair the same category mismatch, and both are frequently correct, so the choice depends on the sentence’s structure and on what the answer set offers. Use “that of” or “those of” when you want an explicit stand-in for the repeated noun: “The output of the new plant exceeds that of the old one” keeps “output” visible through the word “that.” Use the possessive when compression reads cleanly and the owner is a name or a noun that takes an apostrophe naturally: “Tolstoy’s sentences are longer than Flaubert’s” lets the apostrophe carry “sentences.” Match singular nouns with “that of” and plural nouns with “those of,” since the stand-in must agree in number with the noun it replaces. The exam will not present two fully correct answers, so if both a “that of” choice and a possessive choice appear and both seem grammatical, look for a hidden second error, an idiom slip or an agreement problem, that disqualifies one of them. The category match is the goal; either tool achieves it.

What does the “like” versus “unlike” construction require?

A sentence beginning with “like” or “unlike” requires the noun immediately following it to belong to the same category as the subject of the main clause, because “like” and “unlike” set up a comparison between those two nouns. “Like the symphonies of Brahms, the chamber works feel dense” is sound, since symphonies and chamber works are both bodies of music. “Like Brahms, the chamber works feel dense” fails, since Brahms is a person and chamber works are compositions, an illogical pairing. The repair names the matching category: “Like Brahms’s symphonies, the chamber works feel dense,” or recast so the main subject is a person. These constructions are favored by the exam because the comparison sits at the very front of the sentence, several words before a reader braces for a comparison error, so the mismatch hides in plain sight. Run the equal-sign test on the noun after “like” or “unlike” against the subject of the main clause, and the mismatch surfaces immediately regardless of how natural the opening sounds.

Why is trusting my ear risky on SAT idioms?

Your ear was trained by conversation, and conversation is a permissive editor that tolerates nonstandard prepositions every day. People say “different than,” “centered around,” “comply to,” and “preferable than” so routinely that those forms sound correct, yet each is an error under the written standard the exam tests. The assessment is built precisely on the gap between what speech permits and what standard written English requires, so the wrong answer on an idiom item is engineered to sound natural. Worse, you cannot reason your way to the right preposition from the meaning of the words, because the pairings are fixed by convention rather than logic; “comply with” and “adhere to” mean nearly the same thing yet take different prepositions. This combination, that the wrong form sounds right and that meaning offers no reliable guide, is why instinct fails on idioms. The defense is to memorize the standard pairings and to treat a preposition that merely sounds acceptable as a reason to check the choice against your stored list rather than to accept it.

What is the correct preposition after “prohibit”?

The verb “prohibit” takes “from” followed by a gerund, never “to” followed by an infinitive. The standard form is “The policy prohibits employees from using personal devices,” not “prohibits employees to use.” This pairing is heavily tested because the near-synonym “forbid” governs the opposite structure: “forbids employees to use” is standard for “forbid,” which takes the infinitive. The two verbs mean nearly the same thing yet require different constructions, so the exam tests “prohibit” specifically to catch students who borrow the “forbid” pattern. When you see “prohibit,” reach automatically for “from” plus an -ing verb, and treat any version using “to” plus a base verb as the error. The same “from” plus gerund structure appears with related verbs such as “discourage from” and “prevent from,” so recognizing the family speeds you up. The reliable signal is that an infinitive after “prohibit” is always wrong; the gerund after “from” is always the standard.

How do I compare two populations correctly on the SAT?

When you compare one population, dataset, or group to another, make sure both sides of the comparison hold the same kind of thing, and use the plural stand-in “those of” when the noun is plural. “The voting patterns of rural counties differ from urban areas” is broken, because it compares patterns to areas; the repair is “differ from those of urban areas,” where “those” carries “the voting patterns.” A common version compares one group’s rate or average to another group rather than to that group’s rate or average: “The graduation rate at the larger school is higher than the smaller school” should read “higher than that of the smaller school.” Singular nouns such as “rate” take “that of”; plural nouns such as “patterns” or “scores” take “those of.” The stand-in must agree in number with the noun it replaces. These population and dataset comparisons appear often in passages built on social-science or scientific content, so expect the equal-sign test to do steady work whenever two groups are weighed against each other.

What are the most commonly tested SAT idioms?

The core set the exam returns to includes “different from,” “prohibit from,” “regard as,” “responsible for,” “capable of,” “succeed in,” “comply with,” “attribute to,” “debate over” or “about,” “ban on,” “preoccupied with,” “independent of,” “consist of,” “composed of,” “preferable to,” “superior to,” “native to,” “similar to,” “opposed to,” “insist on,” “rely on,” “based on,” “centered on,” “accuse of,” and “sympathize with.” A second tier extends the same logic and includes “result in” an outcome versus “result from” a cause, “contrast with,” “agree with” a person but “agree to” a proposal, “interested in,” “guilty of,” and “devoted to.” The pairings the exam favors most are those where a near-synonym takes a different preposition, such as “comply with” beside “adhere to” or “centered on” beside the nonstandard “centered around,” because the crossover is where memory slips. Drill the core twenty-five first until each fires automatically, then absorb the second tier, since the harder routing draws from the wider pool. None of these pairings can be derived from meaning, so memorization is the only reliable preparation.

Is it “comply with” or “comply to”?

It is “comply with.” The verb “comply” pairs with the preposition “with,” so the standard form is “Manufacturers must comply with the safety standards,” and “comply to” is an error. The pull toward “to” comes from the near-synonym “adhere to,” which is itself correct and means roughly the same thing, so the two verbs cross-contaminate in the ear. Hold them apart deliberately: you comply with a rule and you adhere to a rule, two correct pairings that the exam will test by swapping the prepositions. This is a textbook example of why idioms cannot be reasoned out from meaning, since “comply” and “adhere” are close in sense yet diverge in the preposition each demands. When you see “comply,” let “with” follow automatically and treat “comply to” as a reliable signal that the choice is wrong. The same kind of near-synonym interference shows up with “attribute to” beside “blame on,” so watch for the exam pairing two similar verbs and testing whether you know which preposition each one fixes.

How does the SAT test idiomatic expressions?

The exam tests idioms by underlining a verb or adjective and its preposition, or by offering four answer choices that differ only in the preposition, and trusting you to recognize the standard pairing. The question never announces that it is testing an idiom; it simply presents options such as “capable of,” “capable to,” “capable for,” and “capable in,” and expects you to select “capable of.” Because the difference between choices is a single small word, these items are fast once you know the pairing and impossible to derive if you do not. The exam often embeds the tested preposition near other prepositions in the sentence to prime your ear toward a wrong choice, and it favors verbs and adjectives whose near-synonyms take different prepositions, so that borrowing the wrong pattern is tempting. The defense is to isolate the tested word and its preposition, evaluate that pairing alone against your memorized list, and ignore the surrounding prepositions. Read the operative preposition first, since it is the entire question, and let the rest of the choice serve as camouflage you can set aside.

How do comparison and idiom errors appear together?

The exam’s harder items fuse the two skills into a single sentence so that the correct choice must repair both at once. A sentence might open with a faulty comparison and bury an idiom error later: “Unlike the symphonies of Mahler, Beethoven relied on smaller orchestras and was capable to write tighter movements” contains a comparison flaw, symphonies against a composer, and an idiom flaw, “capable to” instead of “capable of.” The repair fixes the comparison with “Unlike Mahler” or “Unlike the symphonies of Mahler, those of Beethoven” and fixes the idiom with “capable of writing.” Only the answer that corrects both is right, so you must run the equal-sign test and check the idiom pairing in the same pass. These fused items reward students who have made both procedures automatic, since you cannot afford to spend extra time hunting for the second error. When a sentence contains both a comparison word and a verb-plus-preposition pairing, check both deliberately, because the exam frequently plants an error in each.

What is the most common comparison or idiom mistake on the SAT?

The most common mistake across both families is trusting fluency, accepting a choice because it sounds natural rather than testing it against a rule. For comparisons, this shows up as accepting a sentence that compares a quantity to a place because the two proper nouns feel parallel; for idioms, it shows up as accepting “different than” or “centered around” because everyday speech uses them constantly. The wrong answers are engineered to sound right, so smoothness is the symptom of the trap rather than evidence of correctness. The second most common mistake is more specific: writing or accepting “different than” when the standard is “different from,” which is among the most heavily tested single pairings in the entire conventions set. The unifying correction is to invert your relationship with fluency, treating a choice that sounds fine as a reason to run the equal-sign test or consult the idiom list, not as a reason to relax. Diagnose with a procedure, never with a feeling, and the items built to exploit your ear become the fastest, most reliable points in the section.