GMAT Sentence Correction with 20 Practice Questions and Answers

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Every time you put something into writing in a professional setting, it should represent you at your very best—and an important part of that is correct grammar. That’s why business schools care about it, which is why the GMAT tests it. The primary vehicle for testing grammar on the GMAT is the Sentence Correction questions. Keep reading to see what is tested on GMAT Sentence Correction, practice questions for SC, and tips for success. 🙂


Table of Contents


What is GMAT Sentence Correction?

Sentence Correction is one of the three question types on the GMAT Verbal section. (The other two are Reading Comprehension and Critical Reasoning.) Each Sentence Correction (SC) question will have a sentence prompt with an underlined portion. Answer Choice (A) will repeat the prompt exactly. Answer choices (B) through (E) will have variations on this sentence. Only one of these five sentences will be free from errors. Your Verbal section will have ~11-16 SC questions with ~0-2 underlined errors to pick out.

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How can I do well on SC?

First, it’s important to know that the GMAT tests you on two main areas. The first is grammar, the proper grammar rules for formal, academic English. The second is the style. These are not rules exactly, but norms for how formal, academic English should be written. Frequently, there are trap answers that use casual, everyday English constructions that are considered to be against proper style. It’s important to learn both the grammar and style rules that you might be tested on. Keep in mind, if you don’t see any blatant errors, the issue might be ambiguity or clarity. The GMAT prefers simple, straightforward sentences whenever possible, and sometimes that’s the key to a given problem.

Fundamentally, SC is a comparison game. You have to flip back and forth between different answer choices, comparing them to see what tiny differences they have. Furthermore, as with the other verbal question types, it’s important to read critically and use your process of elimination skills. Even if you are strong at the grammar and style rules, you have to be equally strong at looking at a difficult sentence, identifying the key components (e.g. subject, verb, pronouns, phrase structure, idioms, logical flow, and so on), and identifying the ‘splits.’

Splits are features that are different between answer choices. Imagine that we are working on a sentence correction question and our answers include, (A), (B), and (C) which use the verb “run” but (D) and (E) use the verb “is running.” That verb is a split. These will be your main focus as you compare the different answer choices to look for the best one (or as is often the case, the least bad!) You can read a great summary of SC strategy here: GMAT Sentence Correction Strategies.

While you’re thinking about strategy, here are some tips on how to ace GMAT sentence correction!

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How to Master Sentence Correction on GMAT

First, why not check out some sample questions! The post GMAT Sentence Correction Practice Questions is an excellent resource. It compiles links to other blog posts, listed by the rule that they have to do with. So, if you wanted to learn about gerunds and gerund phrases, or when to use like vs. as, you can go to a post that focuses on that rule with examples.

In many ways, SC improvement takes time. You have to learn and re-learn grammar and style rules. This takes time, so be patient with yourself. Use the lesson videos, and make sure to learn from your practice. Also, your process of elimination skills need sharpening and training. The GMAT is a rapid and tricky test, and the more organized and purposeful prep that you do, the more likely it is that you’ll see an increase in your practice scores.


Top 4 GMAT Sentence Correction Tips

Here are our top 4 tips for success with GMAT sentence correction:

  1. Check for Problems with Parallel Construction
  2. Use Process of Elimination
  3. Pay Attention to Word Order
  4. Compare Intended Meaning vs. Grammatical Meaning (i.e. both need to be in sync for the sentence to be correct)

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GMAT Sentence Correction Practice Questions with Explanations

The rest of this post includes twenty practice Sentence Correction questions with explanations. These problems come from our GMAT prep and are a good sample of the different sorts of questions you’re likely to see on your exam. Plenty of different grammar and style rule violations, problems with the structure and logical flow, and some examples of issues with idioms and phrasing.

  1. Getting adequate sleep, a full eight hours every night, the depth of which will be enhanced by a regular regimen of physical exercise, with significant consequences for not only one’s immediate short term health, but also for the immune system’s ability in fighting major illness over the long term.

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    First of all, the GMAT loves the construction “not only X but also Y.” (A) and (B) do this correctly, but (C), (D), and (E) all use the idiom incorrectly. (C) and (E) use “not only … and” and (D) says “not only … and also.”

    Another important split involves a parallel structure. The word “for” can either appear once before and outside the parallel structure— “for not only P but also Q” (no answer choice has this) — or it can be repeated in each term of the parallel structure —- “not only for P but also for Q” (choices (B) & (D) have this correct). It is a classic GMAT Sentence Correction mistake to have the common word once outside and once inside, as in “for not only P but also for Q” (choices (A) & (C) have this incorrect construction). Choice (E) violates the parallelism, so that’s even worse!

    The third split is that “ability” has to follow an infinitive, such as the “ability to do something.” Choices (B) and (C) do this correctly. A common mistake in the use of this word involves the word “in,” such as “ability in doing something.” (A) and (D) make this mistake. (E) avoids this issue by violating the parallel structure which as we saw, is its own problem.

    The fourth and final split involves the missing verb mistake. If you notice, choices (A) & (C) are not complete sentences — the subject “getting” does not have its own verb anywhere in these sentences. Choices (B) & (D) provide the main verb “has” for the main subject “getting.” Sentence (E), with its substitution of “that” for “which” has a particular bizarre structure — technically, in version (E), everything from “the depth of that” to the end would be a complete sentence, but then the whole first part is odd gerund phrase that sticks out awkwardly like a sore thumb and doesn’t fit with the rest. If we fixed the other mistakes in choice (E), we could rectify this problem by constructing two separate sentences following this layout: “Getting adequate sleep, a full eight hours every night, is important. The depth of this sleep will be ….” That would be a possibility in real-life editing. In the GMAT Sentence Correction, though, you have to stick to one sentence, so (E) is out.

    The answer is (B).


  3. Internal combustion engines show an inherent tradeoff between power and fuel efficiency: if a car can race from zero to 60 mph faster, the less fuel-efficient its engine is over time.

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    This sentence focuses on a unique idiom. This idiom is used for comparisons that describe how two quantities change — both getting bigger together, or both getting smaller, or one bigger & one smaller, etc. The structure of this idiom is
    the [comparative adjective][clause #1], the [comparative adjective][clause #2]
    This is a full, independent clause on its own, and does not constitute a run-on sentence. Also, the words “the” are crucial to this idiom. It’s a very strange idiom, almost certainly one that will confuse non-native speakers. Fortunately, it always has the same structure, so you can learn how to use it.
    In this sentence, what are the two comparative adjectives? The first one is “faster”, a single word, and the second, slightly longer, is “less fuel-efficient.” The general format, therefore, should be
    the faster ……, the less fuel-efficient …..
    After each comparative, we should have a full [noun] + [verb] clause. Choice (C) is the only one that follows this pattern. All the others — the “if”, the “when”, the “that much less fuel-efficient” — all of these variants are incorrect. This idiom has a very precise structure, and only choice (C) reproduces this structure correctly in both halves of the sentence. Sometimes that’s all you need to find the answer!


  5. Unfairly criticized during his time, Emperor Claudius expanded the Roman Empire to the east, constructed public works such as aqueducts, having passed laws for protecting the rights and freedoms of Jews throughout the Empire.

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    The first split involves parallelism. We have two verbs in parallel in the non-underlined portion of the prompt, “expanded …. constructed …”, both simple past tense, so we need the third verb, in the underlined section, to be parallel to these. Therefore, we need the simple past tense “passed”, so (D) & (E) are correct. Choices (A) & (B) & (C) instead have the participle “having passed”, which is not parallel at all, so these three are wrong.

    Next, we have a three-way split in the word following “laws” — “for”/”to”/”that”. One correct approach is to use a “that clause” — “laws that protected.” Here, the verb “protected” describes what the laws do. Choices (C) & (E) have this correct structure.
    Choice (B) takes a different approach that is still correct. It uses an infinitive of purpose, which modifies the verb “passed laws to protect …” The infinitive “to protect” gives the reason why the laws were passed, so this is correct.

    Choice (A) tries to express purpose using the structure “for” + [participial phrase]. This is not an idiomatically correct way to express the purpose of an action, so this choice is incorrect. An infinitive of purpose would be the correct way to do this.
    Choice (D) changes the meaning by changing the logic. The purpose, the goal, of passing the laws was to protect the rights of Jews. The rights of Jews were not the cause of anything, which is what the “by” suggests. This choice is incorrect.
    Because of these two splits, the only possible answer is (E).


  7. Since around 1970, with world population of 3.5 billion, they have doubled it to our current level of over 7 billion in 2012.

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    One split is the “with” phrase vs. the “when” clause at the beginning. “When” is the correct word to use here because we’re describing the year 1970, and that’s time. Compare that to the prepositional phrase “with X” has to modify the thing that has X. Here, the phrase is “with a world population of 3.5 billion”, and this raises the fascinating question: what is the thing, or what could be the thing, that has “a world population of 3.5 billion”? It doesn’t make sense to refer to the year 1970 this way, and there’s nothing following the comma that is a likely target, so this preposition phrase structure is problematic. (A) & (B) are wrong.
    Now, let’s look at the split after the comma–we have “they have doubled …”, “doubling”, or “it has doubled.” The “they” is a mystery pronoun, a pronoun with no properly defined antecedent. The GMAT hates mystery pronouns. The choices with the mystery pronoun, (A) & (E), are wrong. The participle “doubling” is also wrong. The only circumstance where “doubling” could be right is if it were modifying some noun that was performing the action of doubling, and such a noun doesn’t exist in this sentence. Therefore, the choices with the participle “doubling”, (B) & (C), are wrong. This leaves only (D), which has an elegant structure that is 100% grammatically correct: “it [Earth’s population] has doubled.”
    (D) is the correct answer.


  9. The more cautious commanders of the Army of the Potomac, such as George McClellan and George Meade, chose to withdraw after costly battles, but commander Ulysses Grant’s strategy was the keeping up of pressure on Lee’s Confederates even after losing a battle to them, and then he occupied positions between Lee’s army and Richmond to invite another open battle.

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    Once again the split is based on parallelism. Grant’s successful strategy had two parts, and these two parts need to be in parallel. Grant kept up pressure, and Grant occupied a position. Those two need to be in parallel.
    (A) “…the keeping up of pressure … he occupied” = complex gerund (very awkward!) + full verb = a failure of parallelism. This is incorrect.
    (B) “keeping up pressure …. to occupy” = gerund + infinitive = a failure of parallelism. This is incorrect.
    (C) “having kept up pressure … he … occupied” = participle + full verb = a failure of parallelism. This is incorrect.
    (D) “to keep up pressure …. to occupy” = two infinitives in parallel = perfect!
    (E) “that he keep up pressure …. then occupying” = full verb + participle = a failure of parallelism. This is incorrect.
    That’s all the information we need to choose (D) as the correct answer.


  11. The controversial restructuring plan for the county school district, if it is approved by the governor, would make there be fewer teachers in schools throughout the county.

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    Let’s start with the phrase directly after the first comma, “if it is approved.” The phrase that comes after a comma often describes a noun in the phrase before the comma. Here, it’s describing the plan. If the plan is approved, there will be fewer teachers.

    Choice (A) doesn’t work because it uses the pronoun “it.” We don’t need a pronoun here. It just makes the sentence more confusing. Is “it” the plan? The school district? Ambiguity is bad on SC, so cross it off. (B) and (C) have the same problem. The pronoun “it” is unnecessary and ambiguous, so we’re left with (D) and (E).

    (E) “would decrease teachers”—very terse, but unclear in meaning; it seems to imply that the plan will make less of teachers as human beings, somehow “decreasing” their essential humanity! This is a sloppy and imprecise way to say what the sentence is trying to say. This choice is incorrect. Choice (D) is clear, direct, and elegant. We don’t need a verb between “if” and “approved” because an “it is” is implied.

    Choice (D) is mistake-free and is the best answer here.


  13. Perennially the world’s leader in tea production, China’s fascination in tea has deep historical roots, as exemplified with the tea ceremony, which has analogs in Japan and Korea.

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    When in doubt, put the subject of the sentence first. That won’t always be true, but it’s a good rule of thumb. (B) and (E) both have China first, and it turns out that (B) is the answer. We’ll discuss that in just a moment, but first, let’s talk about exceptions.

    If we want to say something about China first, we have to do it correctly. (A) doesn’t work, so let’s see why.

    “Perennially the world’s leader in tea production, China’s fascination…”

    Whatever comes in the dependent clause at the beginning has to depend on the subject of the sentence. China is the world’s leader in tea production, so China must be the subject. In (A), China’s fascination is the subject. This doesn’t make any sense. How can fascination, as an emotion or state of mind, be a leader in tea production? (D) is a good example of how to start a sentence with an appositive phrase that leads up to the subject of the sentence. The problem with (D) is the phrase “as an example of.” The correct idiom is “as exemplified by.”

    We’ve crossed off (A) and (D), but what about (C)? The problem with (C) is that it changes the meaning of the sentence. (C) says that China’s tea production is fascinating to the world. It’s also strange to say “China’s tea production perennially leads the world.” If anything we’d say China perennially leads the world in tea production.

    Now we’re down to (B) and (E). Another rule of thumb is to pick the simpler of two sentences, and (B) is simpler. (E) has multiple clunky phrases not to mention its grammar mistakes. China is singular and yet it says “their fascination.” What’s more, if we’re saying China and [its] fascination, then we should say the plural “have” and not the singular “has.”

    (B) has two independent clauses that are combined correctly and free from error.


  15. Walter Mondale had a long difficult struggle leading up to the 1984 Democratic Presidential Primary, though he consolidated his lead for the nomination, but he won only 13 electoral votes in the general election.

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    Watch out for contrast words! (A) has two which makes it nonsensical. Though he consolidated his lead but he won only 13 votes? When we set up a contrast we have to contrast it with something. We could have said, “Though he consolidated his lead, he still lost” or “His campaign was going well, but he only won 13 votes.” Both of these are potential contrasts because they say one thing is the case, then unexpectedly something opposite is the case. (A) doesn’t work because contrasting a contrast is ambiguous and awkward 🙂

    (B) doesn’t make sense in a different way. It makes it sound like the details in the sentence fit together. He struggled, consolidated the lead, only winning 13 votes. If things were going well, why did he only win 13 votes? Cross it off.

    (C) is the answer. After a difficult nomination, he consolidated his lead, but won only 13 votes. Those details make logical sense, and the grammar is fine too. Here is the structure:

    Preposition (“After”) + Noun with some Adjectives (“a long difficult struggle”) + Present Participle (“leading up to the 1984 Democratic Presidential Primary”).
    The present participle here acts as a noun modifier, modifying the noun “struggle.”
    If (D) sounds a little off to your ear, then well done! You’ve found the famous missing verb mistake. If you missed it, don’t worry! You can see that the sentence has a long absolute phrase, then the noun “Walter Mondale,” then a participial modifier, but this noun has no verb before the word “but” starts the second independent clause. The first independent clause doesn’t actually have a verb. “Leading” and “consolidating” are descriptions, not actions. One fix would be changing “consolidating” to “consolidated.”
    Finally (E), which has false parallelism. There are three clauses in a list separated by commas, but just because you put three verbs in a list doesn’t mean you have a grammatical sentence 🙂 The trouble is that it doesn’t explain what the relationship between these clauses is. The correct answer (C) uses a prepositional phrase to explain that he was doing well, and after that he didn’t do so well. The logic is clear. (E) just puts the three details in a row but doesn’t express the logic.


  17. Whereas both Europe and China use standard railroad gauge (1435 mm), Russia deliberately chose the wider “Russian gauge” (1520 mm) that gives greater side-to-side stability in railways cars and, more importantly, acts as a national defense, so that it would block a foreign army’s supply line and preventing these bordering powers from invading by train.

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    The first split has to do with the verbs “gives” and “acts.” Parallelism says that these two verbs have to be in the same form. “Gives” is simple present tense, so we need the same for “acts.” (D) and (E) don’t do this, so cross them off. (A), (B), and (C) remain, so we have to go deeper.
    You may recognize like vs as, but “act like” and “act as” are particular idioms, so need a little more explanation. You can read about that here: A Tricky GMAT Idiom. The idiom “act like” means the subject intentionally decides to imitate the attributes of something else; humans can “act like” something, and, under certain circumstances, more intelligent animals could “act like” something if we attribute some kind of intentionality to them. An inanimate object can never “act like” anything. The idiom “act as” means that, without intentionality, one object takes the role of another. Here, we are talking about railroad gauge, an inanimate object, which could never “act like” anything. We need the construction “acts as.” (A), (C), and (D) do this correctly, but we already crossed off (D), so we’re left with just (A) and (C).
    The final split has to do with parallelism again. The two verbs are “blocking” and “preventing,” which is the participle form. By the way, do you get mixed up between participles and gerunds? Participles act like adjectives and gerunds act like nouns. You can read about this and other tips here: Top Six GMAT Tips for Sentence Correction. “Preventing” is not underlined, so is ‘locked in.’ Whatever is underlined has to match it. Only (C) and (D) do this, so we know that (C) is the answer.


  19. Even-toed ungulates, including pigs, cattle, goats, and sheep, and odd-toed ungulates, such as horses and donkeys, account for all the mammals domesticated for agricultural purposes.

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    Choice (A) is correct! No mistakes. It may help to have that in mind as we discuss what makes the other four choices wrong. (B) makes the missing verb mistake. It says “accounting for”, which means the noun isn’t doing any action. It’s just being described. That makes the sentence incomplete. Next, we can cross off (D) and (E) because they both use “like” to list examples. While English speakers do use this word to list examples in casual speech, it’s considered an error on the GMAT.

    The other two problems are more complex because they have to do with logic. The way that (A), (B), and (E) are phrased, even-toed ungulates is the group which contains pigs, cattle, goats, and sheep. Those four animals are examples of even-toed ungulates, the way that salmon and trout are both types of fish. (C) and (D) say that even-toed ungulates are included among pigs, cattle, goats, and sheep. The GMAT doesn’t require any scientific knowledge, but it does require you to infer relationships based on the words they use in the prompt.

    Finally, the idiom “to account for” means to explain, or show where something came from. For example, how can I account for the fact that I’m soaking wet? I walked here in the rain. Or, coffee accounted for more than half of all food purchases last year. The prompt says that these larger biological groups account for the relatively small group of mammals that are used for agricultural purposes. (D) and (E) reverse this. They say that the mammals in agriculture somehow account for the ungulates. That doesn’t make any sense, so cross these off.

    There you have it! A lot is going on in this problem. First, we have the usual grammar and style mistakes (the missing verb mistake and “like” for a list), but then we have two more subtle mistakes where an error shifts the meaning. It’s important to be on the look-out for all of these errors. They might violate a rule or just change the meaning. Both types of mistakes are a potential reason to eliminate an answer choice, so be on the look-out 🙂


  21. The company is fortunate to have excellent relationships among its employees: they each have a relationship of respect for all the others.

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    This problem includes indefinite pronouns, and those can be tricky. We have a post on this, and I highly recommend it: Indefinite Pronouns and Logic 🙂 We need a phrase like “each other” or “one another.” That’s how you refer to both people in a two-person interaction without specifically referring to them. For example, start with a sentence with only specific nouns:

    The girl threw a ball to her friend.


    They threw the ball with each other.

    The same basic idea is happening in our sentence. The employees have respect for each other. (A) does not use the indefinite pronouns correctly. It’s super wordy and awkward, so cross it off.

    The next split has to do with the structures “each other” and “one another.” They refer to more than one person, so we need a plural subject. (C) and (D) both make this mistake. (C) says “each one” and “one” is singular. Cross it off. (D) is more subtle, but by saying “they each have a relationship of respect” we’re talking about them individually. This is wrong, so cross off (D) as well.

    Now we’re down to (B) and (E), so what is the difference? (E) refers to “they and the other.” “They” refers to the employees, and there isn’t anyone else, so (E) is referring to nothing. Cross it off, and (B) is the answer.


  23. Nine months after the county banned jet skis and other water boats from the tranquil waters of Puget Sound, a judge overturned the ban on the grounds of violating state laws for allowing the use of personal watercraft on common waterways.

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    Right off the bat, (A) and (B) are problematic. When we use the idiom “on the grounds” we usually say “that” and not “of.” It’s possible to use “of,” but we need a simple noun, like, “He wasn’t allowed in on the grounds age.” (C) uses the correct word “that.” but the rest of the sentence is in past tense, and (C) switches to present “violates.” (E) uses passive voice, which is a huge no-no on the GMAT. It makes sense to say “X violates the law,” but it really isn’t a good idea to say “the law is violated.” Also the progressive “were being” is awkward and not necessary. The answer is (D).


  25. Extracting pure aluminum from bauxite and other ores using the Hall-Héroult process, where a vast amount of electrical energy separates the element from aluminum oxide, making aluminum an energy-dense resource with a huge carbon footprint.

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    The sentence begins with the gerund phrase, “Extracting pure aluminum,” and “Extracting” is the subject. (A) and (B) make the missing verb mistake. Every phrase describes the noun but doesn’t have an action, so the sentences are fragments.

    (C) uses the present progressive “is making,” which doesn’t fit here. The rest of the sentence is in the present tense, so we can’t switch to present progressive. The problem with (E) is that it uses “where” to refer to something that isn’t a place. Casual English uses “where” the way that (E) does to refer to a thing. In this case, it’s the process. In formal English, “where” only refers to places. For example, I can say, “New York, where there are many tall buildings…” but I can’t say, “Magoosh, where I get GMAT questions…” because New York is a place and Magoosh is not 🙂 The answer is (D).


  27. At the Battle of Agincourt, the muddy field delayed the advance of the French infantrymen, and this allowed the English longbowmen to be able to inflict significant damage on them, and the English infantry eventually eliminated their reduced numbers easily.

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    Here’s another formal English vs. casual English issue. (A) uses the pronoun “this” to refer to an action, the delaying of the French infantryman. Casual English speakers use “this” to refer to anything and everything, but with formal English, we can’t. “This” has to refer to a specific thing that does an action. It can’t refer to an action.

    (B) makes a tense mistake. It’s all past tense (“delayed’), but then we have “had been able,” which would suggest that the final event came before the other events, and that doesn’t make sense. Eliminating them can’t come before the longbowman or the mud, so this doesn’t work. (D) has two problems. First, it also has a tense issue. It says “tried to advance but had been delayed.” This would mean that being delayed happened before the advancing, which doesn’t make sense because we’re told that they were advancing but then got delayed by the mud. The second issue is that it uses “which” to refer to the delaying. Just like with “this,” we can’t use “which” to refer to an action or situation. Yes, we all talk that way, but on the GMAT it’s not allowed.

    Finally, (E) uses “it” to refer to the action in the previous clause, so it makes that same mistake as (A) and (D). This may feel familiar to you from other SC questions that have “laundry list parallelism”— fact #1, fact #2, fact #3, and fact #4. The problem with this design is that we lose all information about how these facts are related logically. It’s not concise and clear, so it’s a no-go.

    The answer is (C).


  29. The vice-president of the engineering firm argued that the biggest advantage of the proposed alloy for the designs of the new fuselage would not lie in its unusually light weight but in its superior resistance to the corrosive influence of the elements.

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    The first split has to do with the pronoun agreement. The subject is the “proposed alloy.” “Alloy” is singular and (C) and (D) both use “their,” so they’re out.

    The second split concerns the Inside/Outside rule, which you can read about here: Once Outside or Twice Inside. This is a rule that many students don’t see in school, so it’s important to learn it. First start with correlative conjunctions like these:

    Both X and Y
    Neither X nor Y
    Not X but Y
    Not only X but also Y

    Each of these has two individual conjunctions that describe the two halves of some parallelism. Whenever you use these, the parallelism has a clear start at the beginning of the first word. Anything that is within the “both X and Y” structure is “inside,” and anything that comes before or after it is “outside.” If a preposition applies to words in both branches of the parallelism, we have two options:

    Once Outside: to both X and Y
    Twice Inside: both to X and to Y

    These are the ONLY valid options. You’ll commonly see other constructions that are considered errors:
    One inside: both to X and Y
    Once outside, once inside: to both X and to Y

    In this question, we say “not … but …” so where should we put the preposition? The word “lie” has to go once on the outside and the preposition “in” has to appear twice inside. Another way to think about this is that we need “lie not in” so we can get the first “in” inside and “lie” on the outside. The second “in” comes later in the sentence with “but in its superior resistance.” (B) is the only choice to get this right, and it’s the answer. If this rule feels confusing to you, take some time and look carefully at the other answer choices to see what they do and demonstrate to yourself that they don’t follow the rule correctly. There’s also another problem in this post that has an issue with this same rule.
    Choices (A) and D) both put “lie” after the word “not,” so it appears on the inside, which is wrong. (C) and (E) put the preposition “in” before the word “not,” which is once on the outside and also wrong. (B) is the answer.


  31. The ability of neuroscientists to pinpoint the exact locations in the brain where complex sensory responses to a variety of stimuli occur, such as a logic-based board game or a series of violent images, have become ever more precise.

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    Choice (A) doesn’t work for two reasons. First the subject of the sentence, “the ability of neuroscientists,” is indirect, which is stylistically problematic. Then there’s a subject-verb agreement error because “have become” is plural, and ‘ability’ is singular. They try to hide the subject-verb agreement error by putting a bunch of modifiers in between the subject and verb, which is why it’s always a good idea to check all nouns and verbs every time you read a sentence 🙂

    Choice (B) tries to hide an error as well. The words ‘able’ and ‘ability’ have to go with an infinitive. An infinitive is a verb in a form like “to run” or “to see.” Here the preposition is “in” which is idiomatically incorrect.

    On to choice (D)! The phrase “where complex sensory responses are to occur” is a problem. This phrasing makes it sound like there is some cosmic plan that these responses must occur. This doesn’t fit with the natural science context, so it’s wrong. As you can see, the hardest SC problems have extremely subtle errors in them.

    Choice (E) is similar to (A) in many ways. It has a strange subject (“Neuroscientists’ ability” is clunky), the verb is super far away from the subject, and the verb has an error. In this case, “became” is past tense and the rest of the sentence is in present.

    Choice (C) is the answer.


  33. Dante Rossetti and his colleagues, in calling their group the Pre-Raphaelite Brotherhood, sought a return to the classical ideals of painting that held sway before Raffaello, to what governed the work of 15th century artists such as Sandro Botticelli.

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    Because Choice (A) is the answer, let’s skip it for now and come back to it at the end. Choice (B) uses “would govern” which doesn’t fit here. “Would govern” in this context refers to what could be in the future from the perspective of the past, which is not what we’re doing.

    Choice (C) changes the meaning of the sentence. The ideals governed the 15th century artists. (C) makes it sound like Raffaello himself governed the artists, which doesn’t make any sense. This choice also uses ‘like’ to introduce an example, which isn’t allowed on the GMAT. Choice (D) has the same problem. There’s no comma, so it still sounds like we’re saying that Raffaello did the governing. (E) is exactly the same. It sounds like Raffaello was the governing force, and it uses ‘like’ for an example.

    Choice (A) is the correct answer. “Classical ideals” is a noun, and “what governed the work of 15th century artists” is a substantive clause, so that’s legitimate for parallelism. None of the other four answer choices execute the parallel structure correctly.


  35. One of Hannibal’s successful battle techniques was charging wild elephants directly at the Roman armies, trampling infantry and inducing disarray in the ranks, but Scipio’s successful counterstrategy was to command that his men should part, creating channels that allowed the elephants simply to pass through, with them killing the elephants behind his ranks.

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    This one is tricky because it involves parallelism at a couple of different levels. First of all, we are comparing Hannibal’s vs. Scipio’s approaches. Hannibal’s technique was “charging”, so Scipio’s counterstrategy has to be parallel to this. To match “charing” is has to be “commanding”, not “to command.” It’s important to note that if it weren’t for parallelism, the use of the infinitive in this context is completely allowed.

    After the word command/commanding, the most natural idiom is an infinitive: to command B to do X. The “that”-clause structure here, “that his men should part”, is very awkward. It does sound like fancy or old-fashioned English, which is usually a good sign that something is wrong. Reject (A) & (D).

    The structure “with them killing” is 100% wrong. In general, the GMAT hates “with” + [noun] + [participle] to encapsulate an action. If we want to talk about an action, we need to use a fully bonafide verb. Another reason to reject (A).

    Scipio is commanding his men to do two things: (1) to part, and (2) to kill the elephants. These two actions need to be in parallel as well. Furthermore, the correct idiom is “command” + [infinitive], while “command” + [gerund] is 100% wrong. Choice (C) correctly has two infinitives, “to part” and “to kill”. Choice (C) is the only answer that has correct parallelism in both places, so this is the only possible answer.

    Both (D) and (E) mix up the two things that Scipio commanded the men to do. Losing that distinction changes the meaning of the sentence. Remember, parallelism is not automatically correct especially when it entails a major change in meaning.


  37. If medical researchers are correct, then the human microbiome, made up of the microorganisms in our body, may hold the cure to diseases that have long plagued humanity, amounting to a major oversight in Western medicine that has, until recently, all but ignored any such role of the microbiome.

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    On the hardest SC questions, you may face a summative modifier, which is a word that ‘encapsulates’ the action of the preceding clause. In this case, the word “amounting” could refer to microbiome, diseases, or humanity. Which of these three is the author of this sentence arguing accounts for the oversight?

    To do this properly, we need a word that encapsulates or captures the preceding phrase. Something that will wrap it up and refer to all three at once. This is called a summative modifier. It sums up what was just said. Luckily, the GMAT will never give you more than one summative modifier and build the question out of your picking the correct one. As you can see, “discovery” is the summative modifier. It works well and it’s the only one.
    This is such an important insight because right away we can eliminate (A), (D), and (E). Any form of “amounts” is fundamentally ambiguous, and therefore a violation of the style rules. All we have to do now is compare (B) and (C) and figure out which is best (or least wrong, as is often the case).

    In (B), the word “which” refers to the phrase “a major oversight.” We know this because when “which” is used, it refers to the subject of the noun phrase that comes right before it. (B) is making an error, then, because the major oversight is not the thing that is doing the ignoring the role of the microbiome. The oversight is ignoring the microbiome. (C) states this correctly. Western medicine is what has been ignoring the microbiome. That is the subject that needs to be described as making an oversight. That’s why (C) is the answer.


  39. The FDA enacted these recent restrictions both to prohibit individual physicians from forming financial partnerships with pharmaceutical companies and to forbid the companies to advertise directly to the physicians.

    Show Answer and Explanation

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    This sentence has two similar verbs that form two completely different idioms. The verb “to prohibit” always takes “from” + [gerund]; using the infinitive is 100% incorrect with this verb. By contrast, the verb “to forbid” always takes the infinitive; using “from” + [gerund] is 100% incorrect with this verb.

    Choice (A): “prohibit … from … forbid … to” = correct
    Choice (B): “prohibit … to … forbid … to” = idiom mistake
    Choice (C): “prohibit … from … forbid … from” = idiom mistake
    Choice (D): “prohibit … from … forbid … from” = idiom mistake
    Choice (E): “prohibit … to … forbid … from” = double-whammy idiom mistake

    This is all we need to identify the correct answer (A). There are also other issues at play here, so we’ll talk about them too. One important rule that we’ve discussed elsewhere on this post is the Once Outside, Twice Inside rule. This rule comes into effect when we have correlated conjunctions—that is, a pair of conjunctions that mark the two halves of the parallelism: examples include “both X and Y,” “neither X nor Y,” “not X but Y,” and “not only X but also Y.” When any of these are used, the parallelism has a clear start at the beginning of the first word. Anything that is within the “both X and Y” structure is “inside,” and anything that comes before or after it is “outside.” If a preposition applies to both words, there are two ways we can go:
    Once Outside: to both X and Y
    Twice Inside: both to X and to Y

    In this question, the parallel elements are the infinitive “to prohibit … and to forbid.” Thus, we could have:
    Once Outside: to both prohibit and forbid
    Twice Inside: both to prohibit and to forbid

    The incorrect patterns are
    Once inside: both to prohibit and forbid*
    Once outside once inside: to both prohibit and to forbid
    Choice (A): twice inside = correct
    Choice (B): twice inside = correct
    Choice (C): once outside, once inside = incorrect
    Choice (D): twice inside = correct
    Choice (E): once outside, once inside = incorrect
    Finally, there is one more error in this problem that is good to notice. The “both X and Y” structure is a standard parallelism frame. In this structure, X and Y need to be in parallel: two infinitives. Choice (B) violates the parallelism: “both to prohibit … while forbidding.” Choice (B) is incorrect.
    For all of these reasons, the only possible answer is (A).

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