In our GMAT Case Study series, we’ll take a close look at the key concepts behind GMAT practice questions. This week: idiom errors.

Even the most diligent students occasionally have nightmares about GMAT sentence correction grammar. SC can be particularly frustrating if you are not a native English speaker and have trouble just understanding what the sentence is saying.Â Luckily, there are plenty of strategies to help test-takers — both native and non-native speakers — succeed! Before we get into too many details, let’s try an example:

In the last few decades, physicists have identified the existence of different “flavors” of subatomic particles called quarks, most of them as small or smaller than the electron, which display a property known as color charge.

(A) most of them as small or smaller than the electron, which display

(B) most of them as small or smaller than the electron and displaying

(C) mostly as small or smaller than the electron, displaying

(D) mostly at least as small as the electron, which display

(E) most of them at least as small as the electron, displaying

Give it a shot, then read on for the explanation and more SC strategy tips.

Not sure what “quarks” and/or “electrons” are? Don’t worry! Lucky for you, the content of this sentence is pretty much irrelevant. As long as you can identify the parts of speech, you can get a handle on what the sentence is testing.

Try to approach sentence correction the same way as math. Ignore the vocabulary and writing style and instead think of the sentence as an equation. Your job for SC questions is to balance the equation by making sure all the necessary elements are in place.

Okay, back to the sample question. If English is not your first language, then it may be difficult for you to spot the idiom error in the sentence. However, we can start with a more basic grammar error, which you have already likely encountered in a grammar book or GMAT question.

Look at the word “which.” The phrase, which display does not make sense here because adjective clauses that start with “which” MUST refer to the object they follow. Here, which display would refer to electron. “Electron, which display” does not make sense grammatically — it would have to be “displays.” Furthermore, it is not the electron that is displaying a property known as color charge — it is the quarks that are doing this.

Again, you don’t need to know what “quarks” and “electrons” are to answer this question — you just need to know that they are nouns. To balance the grammar “equation” here, we need an expression that either uses the word “which” logically, or does not use it at all. Therefore we can immediately eliminate answer choices A and D.

Let’s look at another part of the sentence: the word “most.” Notice how two answer choices use the word “mostly”? If you remember your parts of speech, you know that we add “-ly” to adjectives to turn them into adverbs. Here “most” is describing “quarks,” a noun. Therefore we should use an adjective, not an adverb. We can eliminate answer choice C.

Now it is down to just B and E. If you are unaware of the idiom error (“as small or smaller than” is incorrect. You cannot say “as X…than”) then try to judge the two options by sound. Which one is less awkward? Choice E, with its balanced use of commas and adjectives, reads much more naturally than B.

And it just so happens that choice E is correct. What’s the moral of the story? Break down an SC question into components and begin eliminating wrong answer choices based on the errors you know. You will improve your chances of finding the right answer and save time trying to decipher meaning.

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Jonathan is a software engineer at Knewton. He graduated from New York University with degrees in English and Music. He spends his days at Knewton developing the adaptive learning platform students use to get customized content every day. Jonathan speaks three languages (English, Japanese, Chinese) and is an avid comic and video game fan.

Great post! Idioms are SO important for the sentence correction section!

Great post! Idioms are SO important for the sentence correction section!

• Kissthegmat

Thank you for the post. It was helping.

• Kissthegmat

Thank you for the post. It was helping.

• Guest3

It’s really funny to see comments for SC GMAT examples with idiomatic mistakes… LOL

• Guest3

It’s really funny to see comments for SC GMAT examples with idiomatic mistakes… LOL

• AC

Hm.
Perhaps this is somewhat bold, but I am not sure I agree with you (as some justification- I have done the GMAT, although admittedly 3 years ago; at the time I got 99th percentile on the Verbal part).
In terms of the which clause, it should be noted that it is an acceptable use of grammar in this context to add an extra, non-essential description between commas – treating these commas almost as one treats brackets. Thus, the ‘which’ is actually referring to the quarks – plural, therefore ‘display’ is correct.
However in reality the ‘which’ should be a ‘that’ in this context, so this gives the game away that all answers with a ‘which’ are incorrect.

Anyway, when I first started writing this I felt that B was a more correct answer than E (my reading reflex being to think that the word ‘being’ needed to come before ‘at least’, to anchor the statement) but I have to admit that, on reading the sentence aloud both ways, B does sound rather clumsy and thus E would be more correct.

• AC

Hm.
Perhaps this is somewhat bold, but I am not sure I agree with you (as some justification- I have done the GMAT, although admittedly 3 years ago; at the time I got 99th percentile on the Verbal part).
In terms of the which clause, it should be noted that it is an acceptable use of grammar in this context to add an extra, non-essential description between commas – treating these commas almost as one treats brackets. Thus, the ‘which’ is actually referring to the quarks – plural, therefore ‘display’ is correct.
However in reality the ‘which’ should be a ‘that’ in this context, so this gives the game away that all answers with a ‘which’ are incorrect.

Anyway, when I first started writing this I felt that B was a more correct answer than E (my reading reflex being to think that the word ‘being’ needed to come before ‘at least’, to anchor the statement) but I have to admit that, on reading the sentence aloud both ways, B does sound rather clumsy and thus E would be more correct.

• http://pulse.yahoo.com/_U6B4MVKDYPK2D54G65ATP4A37A sudhanshu

Wells perhaps, it is not that tough after all.

• http://pulse.yahoo.com/_U6B4MVKDYPK2D54G65ATP4A37A sudhanshu

Wells perhaps, it is not that tough after all.

• Sanjeev

There are two problems with choice E.
First:”at least” is redundant.
Second: “and” must come before displaying, or else verb+ing indicates cause-effect relationship, making(Verb+ing) me to infer the reason for displaying property an identification carried out by scientists.
to make the choice E right we need following correction in the sentence.
“most of them as small as the electron and displaying”.
Now both “small” and “displaying” will work independently as an adjective modifying quarks.
Among the above choices Choice E is only possible as idiom in other options is wrong, although Choice E also has errors. Redundancy can be ignored but “,displaying” is confusing.

• Sanjeev

There are two problems with choice E.
First:”at least” is redundant.
Second: “and” must come before displaying, or else verb+ing indicates cause-effect relationship, making(Verb+ing) me to infer the reason for displaying property an identification carried out by scientists.
to make the choice E right we need following correction in the sentence.
“most of them as small as the electron and displaying”.
Now both “small” and “displaying” will work independently as an adjective modifying quarks.
Among the above choices Choice E is only possible as idiom in other options is wrong, although Choice E also has errors. Redundancy can be ignored but “,displaying” is confusing.

• Sanjeev

There are two problems with choice E.
First:”at least” is redundant.
Second: “and” must come before displaying, or else verb+ing indicates cause-effect relationship, making(Verb+ing) me to infer the reason for displaying property an identification carried out by scientists.
to make the choice E right we need following correction in the sentence.
“most of them as small as the electron and displaying”.
Now both “small” and “displaying” will work independently as an adjective modifying quarks.
Among the above choices Choice E is only possible as idiom in other options is wrong, although Choice E also has errors. Redundancy can be ignored but “,displaying” is confusing.

• http://pulse.yahoo.com/_XXHZUMHOPZ75YT56KRFGMV6ZFQ Rishab

pretty straight forward idiom q. The idiom being tested is as…as.Only D and E correct this error.D has relative pronoun error and a s-v error (displays and not display). Also which is modifying electron and this is incorrect. The sentence intends to modify quarks, so a participle modifier is the best.

For non native speakers. B is WRONG. it uses as… than .This is ALWAYS wrong. You can say as…as , more…than,less… than, greater… than etc but not as…than.

Redundancy, along with awkwardness, is the LAST thing you wanna check in your sentence.