GMAT Sentence Correction: 8 Most Commonly Tested Errors

How they are tested: Idioms are expressions native to the English language. There are two part Idioms such as “neither…nor” and” between…and” as well as prepositional idioms like “interested IN” and “afraid OF.”
How to Study: Keep a study sheet for Idioms and add to it every time you encounter a new one. Make flashcards with the first part of the Idiom on the front and the second part on the back.

How it’s tested: SCs love to give long sentences where the main subject and the verb are separated by many words or clauses. You must identify the subject of each sentence and make sure the verb matches it in number: a plural subject takes a plural verb, and a singular subject takes a singular verb.
How to Study: Practice identifying subjects and verbs whenever you read and in every Sentence Correction question you do. Don’t be confused by other nouns or pronouns in the sentence. Find the noun(s) or pronoun(s) that is doing the action of the verb—that’s the subject.

How they are tested: The most common error associated with pronouns is pronoun-antecedent agreement. The antecedent is the word the pronoun is replacing. A pronoun must have a clear antecedent in the sentence; the lack of an antecedent is itself an error.  The antecedent may often be present, but will disagree with the pronoun in number.
How to Study: Learn the difference between subject pronouns and object pronouns, and how they are used in sentences. Make sure to match any pronoun in a Sentence Correction back to its logical antecedent.

How it’s tested: Parallelism is tested on the GMAT in a series of phrases or items in a list. In parallel construction, the phrases or items must be in the same form. This can be tested with a number of parts of speech: nouns, verbs, prepositions, etc.
How to Study: Read as many examples of parallelism as you can. Understand the difference between the infinitive and participle verb forms. Look for commas between phrases as a clue that the sentence may be testing parallelism. Ask yourself: are these phrases part of a list?

How they are tested: Modifiers are words and phrases that describe nouns. Adjectives, adverbs and modifying clauses will be incorrectly placed, or in the wrong form. Adjectives can only modify nouns, while adverbs can modify verbs, adjectives, and other adverbs. Be on the lookout for suspicious adverb-noun and adjective-verb pairings. Also be aware that many sentences will begin with a modifying phrase and a comma. The subject after the comma must be the person or thing doing the action of the modifying phrase.
How to Study: You will need to review adjective and adverb usage from a good English grammar book, and learn the common forms of each (for example, most adverbs end in –ly). This is worth doing even if you are a native English speaker, as we frequently interchange adverbs and adjectives in everyday speech. What “sounds” correct may not in fact be so!

How they are tested: Compound subjects, as the name implies, are subjects that are put together with a conjunction such as “and.” The key to identifying compound subjects is to notice that the conjunction “and” renders the subject plural.
How to Study: Circle the “and” to remind yourself that the subject is plural. Look at this simple example: John, Susan, and I, despite our shared taste for Indian cuisine, are still intimidated by extremely spicy foods.

How they are tested: Collective nouns represent entities made up of many parts, but they are always treated as singular units, and so they agree with singular verbs. Some popular collective nouns include “team,” “group,” “audience,” “committee,” “corporation,” “company,” “family,” and “jury.” Notice that all of these nouns incorporate many parts but they agree with singular verbs, e.g. “my family is here,” “the jury has spoken,” etc.”
How to Study: Eliminate Prepositional Phrases. On the GMAT, collective nouns will often come paired with prepositional phrases that make it seem as if they should agree with plural verbs, e.g. the team of lawyers is here. Often, our natural instinct in this case is to make the verb plural, since we hear the plural in the prepositional phrase “of lawyers.” Get in the habit of crossing out the prepositional phrases attached to nouns so that you avoid this mistake.

How they are tested: Indefinite pronouns are words the replace nouns; here is a table of some indefinite pronouns, organized by those that are always singular, always plural, and singular or plural (contingent upon prepositional phrase attached).

Singular	Plural	Singular or Plural
Another	Both	All
Anybody	Few	Any
Each	Many	More
Everybody	Others	Most
Much	Several	None
Nobody		Some
Somebody

The singular indefinite pronouns far outnumber the plural and “singular or plural” indefinite pronouns (the list, in fact, is far from complete). For the GMAT, worry about singular and “singular or plural” indefinite pronouns since we rarely make mistakes with plural indefinite pronouns.
How to Study: For Singular Indefinite Pronouns, cross out prepositional phrases and watch out for pronouns that refer to indefinite pronouns. Here are two examples:

• Each of my friends is going to business school. (Cross out the prepositional phrase to realize that “each” agrees with a singular verb).
• Everybody knows that his or her grade will improve on the test. (Watch out for pronouns that refer to singular indefinite pronouns; while many of us would say “their” instead of “his or her,” we must remember that “everybody” is a singular pronoun).

For “Singular or Plural” Indefinite Pronouns, let the prepositional phrase do the talking. With these pronouns, the noun after the prepositional phrase is the one that determines the verb.

• All of my friends are at the party
• None of my training was utilized.