If you are a native English speaker, there are many times you can rely on your ear to tell you the correct answer on GMAT sentence correction. However, sometimes your ear can lead you astray, because there are things we say in colloquial English that are actually incorrect on the GMAT. Take a look at this example:
After he won the chess tournament, Sam’s parents were proud of him.
This might be something you might say in colloquial English, but on the GMAT this would be incorrect. If someone said this to us, it would be easy to figure out that the “he” means Sam. However, you can never make assumptions for the test makers on the GMAT, and a possessive is never a proper antecedent for a pronoun. Another problem with this statement is that “After he won the chess tournament” is modifying the noun “Sam,” which means that “Sam” should go directly after the comma, not “his parents.”
Another way we speak in everyday English that would be incorrect on the GMAT, is using the pronoun “they” to refer a singular person when gender is unknown. For example:
If a friend calls, will you tell them that I will meet them at the restaurant at 7pm?
In this statement, “them” is used to refer to one of the author’s friends (singular). This is incorrect. Instead of “them,” the author should use “him or her.”
Another GMAT problem we might say in everyday english is using pronouns with slightly ambiguous antecedents. For example:
The hospital’s board discussed ways to prevent a strike, which would shut it down for at least a week.
Again, if someone said this to you in a conversation, you could safely assume that “it” was referring to the hospital. However, on the GMAT, you cannot make such assumptions. According to GMAT grammar, there are two singular antecedents that “it” could be referring to: the “board” (because collective nouns are singular) and the “strike.” It cannot actually refer to the hospital itself, because a possessive cannot be an antecedent for a pronoun. If there is ever two possible antecedents for a pronoun and they are the same in number (either both plural or both singular), and it is not abundantly clear which one the pronoun refers to, pick another answer choice. A general rule of thumb is, the clearer the meaning the better.