Sentence correction questions consist of sentences. Sentences are made up of words, and each word in a sentence has a function. The parts of speech in the English language that are important to know are verbs, nouns, pronouns, adjectives, adverbs, conjunctions and prepositions.

1. Verbs

Every sentence has a verb, which means that a sentence is not complete without one. There are three types of verbs:

1. Action Verbs

These verbs state what the subject of the sentence is doing. Run, jump, compile, and learn are examples of action verbs.

2. To be Verb

The verb to be (conjugated as am, is, are, was, were, been, and being) functions like an equal sign. It equates the subject with a noun or adjective.

For example: John is successful. It means John = successful.

3. Linking Verbs

These words join (or link) the subject to an adjective that describes the condition of the subject. Like the verb to be, they express a state of the subject, but they provide more information about the subject than to be verbs do. Common linking verbs are feel, seem, appear, remain, look, taste, and smell.

2. Nouns

Nouns are defined as persons, places, or things. They provide the "what" of the sentence. A noun can function in a sentence in different ways:

1. The subject plays the principal role in the sentence. It’s what the sentence is about or who is doing the action.

2. A direct object receives the action of an action verb.

3. An indirect object receives the direct object. Sentences with direct objects don’t need indirect objects, but you need a direct object before you can have an indirect object.

4. The object of a preposition receives a preposition.

5. The object in a verbal phrase serves as the receiver of the gerund (Gerund is a verb form that functions as a noun, like singing).

6. Appositives clarify or rename other nouns.

7. Predicate nouns follow the verb to be and regard the subject.

One of the most important things to remember about nouns and verbs on the GMAT is that the subject and verb of a sentence have to agree in number.

3. Pronouns

Pronouns rename nouns and provide a means of avoiding the needless repetition of names and other nouns in a sentence or paragraph. To correct these errors, you need to be familiar with the three types of pronouns: personal, indefinite and relative.

1. Personal Pronouns

These words rename specific nouns. They take two forms: subjective and objective.

  • The subjective personal pronouns are I, you, he, she, it, we, and they. Subjective personal pronouns are used when the pronoun functions as a subject or predicate noun.
  • The objective personal pronouns are me, you, him, her, it, us, and them. Objective personal pronouns are properly used when they function as an object in the sentence.

2. Indefinite Pronouns

These pronouns refer to general nouns rather than specific ones. Some common examples are everyone, somebody, anything, each, one, none, and no one. Most indefinite pronouns are singular, which means they require singular verbs.

3. Relative Pronouns

These words, like that, which, and who, introduce adjective clauses that describe nouns. Who refers to persons, which and that refer primarily to animals and things.

4. Adjectives

Adjectives describe and clarify nouns and pronouns.

For example: The secretive culture of the corporation created discontented employees. Secretive defines the kind of culture and discontented describes the feeling of the employees.

With sentence correction questions, make sure adjectives are positioned correctly in the sentence so each adjective modifies the word it’s supposed to.

5. Adverbs

Adverbs are like adjectives because they add extra information to the sentence, but adjectives usually modify nouns, and adverbs primarily define verbs. Adverbs include all words and groups of words (called adverb phrases) that answer the questions where, when, how, and why.

For example: The stock market gradually recovered from the 2008 crash. Gradually defines how the stock market recovered.

Some adverbs modify adjectives or other adverbs. Positioning adverbs correctly is important on the GMAT. Separating adverbs from the words they modify makes sentences imprecise.

6. Conjunctions

Conjunction joins words, phrases, and clauses. The three types of conjunctions are coordinating, correlative, and subordinating.

The seven coordinating conjunctions - and, but, for, nor, or, so, and yet - are the ones most people think of when they consider conjunctions.

Correlative conjunctions always appear in pairs: either/or, neither/nor, not only/but also. These conjunctions correlate two similar clauses in one sentence.

Subordinating conjunctions introduce dependent clauses and connect them to independent clauses.

7. Prepositions

These words join nouns to the rest of a sentence. Common examples are: about, above, at, for, in, over, to, and with. A preposition cannot function within a sentence unless the preposition is connected to a noun, so prepositions always appear in prepositional phrases. These phrases consist of a preposition and noun, which is called the object of the preposition.

For example: The woman in the suit went to the office to sit down. The preposition in relates its object, suit, to another noun, woman, so in the suit is a prepositional phrase that works as an adjective to describe woman; to the office is an adverbial prepositional phrase that describes where the woman went.