This post was written by Sean Murphy. For more expert GMAT prep advice, check out the Knewton blog.
It is definitely important to learn the rules of grammar when studying Sentence Correction. But as a GMAT instructor, I’ve noticed that some students try to apply grammar rules so ruthlessly that they sometimes do not understand how certain sentences can be correct. When we teach the past perfect tense, for example, we teach that the past perfect tense is used when a sentence contains two events that occur at different times in the past. The past perfect should be used for the action that occurred first.
After I ate a lobster, I had gone swimming.
This sentence is incorrect, because the past perfect (indicated by the auxiliary verb – also known as “helping verb” - “had”) is used for the action that occurred second. Many students would correct the sentence thus:
After I had eaten a lobster, I went swimming.
But this sentence is also correct:
After I ate a lobster, I went swimming.
I can anticipate my students’ protests: “But I thought you said that the past perfect is used when two events occur in the past, one before the other!” Well, yes, I said that -- but I never said that the past perfect MUST be used. If the order of events is absolutely clear, as it is in the example immediately above, the simple past may be used.
In GMAT Sentence Correction questions, the grammar must be correct AND the logic must be clear. By focusing so much on grammar and neglecting to consider logic, many GMAT students miss correct answer choices because they incorrectly think there is a violation of a grammar rule, or they chose a grammatically correct answer choice that is not logically clear.
Here is another example:
The mountains of Peru, which are very high, are filled with diverse species of llama.
You maybe remember your teacher saying that “which” must modify the noun immediately before it. In that case, the sentence above would be wrong, because “which” clearly is intended to modify “mountains” not “Peru”. But the sentence is correct. The actual rule with “which” is that it must clearly modify a preceding, specific noun. The plural form of the verb after the “which” clearly indicates that it modifies “mountains.”
Some students, especially those who have a first language other than English, understandably want to learn a set of rules that can be applied consistently. The English language, however, tolerates more exceptions to its “rules” than many other languages, and the reasons for this are historical. English is a relatively recent language on the world scene, and it is a hodge-podge, a mixture of Anglo-Saxon, Norman French, Shakespeare (and, most recently, Sarah Palin). English was still evolving at a rapid pace when mass literacy emerged in the 16th century and forced a codification of its rules. The “rules” that were established reflected English’s chaotic, fractured nature. When mass literacy came to other languages, these languages had already existed for much longer, and had a much more refined system of grammar in place.
In my next post, I’ll look at some actual GMAT Sentence Correction problems where a “rules-based” approach has gotten students into trouble. Till then, remember that logic can be just as important as grammar. If a sentence seems completely logically clear, but you feel there might be a modification, tense, or pronoun error, you might be trying to apply a grammar rule too rigidly.
