To check the grammar of a sentence, you must make sure the various parts of speech and the punctuation marks are used correctly. First, you should determine whether the sentence is singular or plural so that you can make sure the parts of speech are paired correctly. For example, a singular subject requires a singular verb, and a plural pronoun requires a plural antecedent. Second, you should make sure modifiers, such as adjectives and adverbs, are used correctly. Finally, you should check punctuation marks such as commas to make sure they are not misplaced or missing.

Subject-Verb Agreement

Verb tenses tell when the action is happening: past, present or future. A subject can be singular or plural, so each verb tense has a singular and plural version. When you're checking a sentence, make sure the subject and the verb tense match. For example, in the sentence He plays tennis every Saturday, the subject, he, is singular, so the verb is in the present tense. Checking subject-verb agreement is trickier if you have a more complex sentence. For example, the sentence The group of children, including the three troublemakers, were in the gym is incorrect. The group is the subject and is singular, so the verb should be changed to was. When you have a prepositional phrase in a sentence, such as of children, remember that the subject will not be part of the prepositional phrase. Look at the word before the prepositional phrase.

Pronoun Reference

Pronouns take the place of proper nouns, like using him instead of Bob, or they instead of two or more people. Pronouns must refer to a specific person or object, so make sure they are clearly referenced in the sentence you're checking. Watch for undefined pronouns, and make sure the reader knows exactly to what object or person each pronoun refers. For example, in the sentence Mary told Sarah that she was getting a raise, the pronoun she could be referring to either Mary or Sarah. The sentence must be revised to eliminate the unclear pronoun reference. Here are two possible revisions: Mary told Sarah that Sarah was getting a raise or Mary told Sarah, "You're getting a raise."

Adjectives Verus Adverbs

Essentially, adjectives describe nouns, while adverbs describe verbs and usually end in ly. Adverbs describe how, when, how often, where or why something is done. Adverbs that do not end in ly include well, almost and fast. You may be used to hearing people use adjectives instead of adverbs in everyday speech, and people often write like they talk. For example, you may hear someone say, "The car drives smooth." But, smooth is an adjective and should only be used to describe a noun. To correct this sentence, change smooth to the adverb smoothly, because it is describing how the car drives. Another common mistake is to confuse good and well. While You did good is a common phrase to use when praising someone, it is actually grammatically incorrect. Because good is an adjective, it should be replaced with the adverb well when you're referring to how someone did.

Comma Placement

A comma shows where a brief pause occurs in a sentence. Commas are only used in certain situations. A comma should be used to separate an "introductory element" from the main part of a sentence. For example, a comma follows the phrase for example in this sentence because it is used as an introductory element. An introductory element can be a word, a phrase or a clause. Commas are also used to separate a series of three or more words, phrases or clauses. If you are writing in a style that uses the serial comma, such as Chicago, you would put a comma before the last item in a series as well (for example, ... words, phrases, or clauses). You should also use commas to set off extra information about something, such as the part of this sentence that gives the time of the earthquake: The earthquake, which struck early in the morning, woke residents and caused minor damage. Finally, if you are combining sentences to form a compound sentence, you may choose to use a conjunction, like but or and. If the sentence you are checking is compound, make sure there is a comma before the conjunction. For example, if you are checking the sentence He ran out the back door, and she followed him, make sure there is a comma before and. If the sentence is not compound, meaning there is no subject in the second part of the sentence, you do not need a comma. For example, in the sentence He ran and did not stop, you do not need a comma before and.