AGREEMENT
Subject/Verb
Every verb must agree in number with its subject, both in person (first, second, or third) and in number (singular or plural).
In a simple sentence, making a verb agree with its subject is a straightforward task: Hector Ruiz is a strong competitor.
Confusion sometimes arises when sentences are a bit more complicated. For example, be sure to avoid agreement problems when words come between the subject and verb. In the following examples, the subject and verb are underlined.
The analysis of existing documents takes a full week.
Even though documents is a plural, the verb is in the singular form because the subject of the sentence is analysis, a singular noun.
The answers for this exercise are in the study guide.
Either/or and Neither/nor: When either/or or neither/nor are used in a sentence, the verb should agree with the noun closest to it.
Neither Bill nor his parents work in the store on Sundays.
Parents (plural) is the noun closest to the verb work, so the verb is plural as well.
With the words number or variety: To decide whether to use a singular or plural verb with subjects such as number and variety, follow this simple rule: If the subject is preceded by a, use a plural verb.
A number of products are being displayed at the trade show.
If the subject is preceded by the, use a singular verb.
The variety of products on display is mind-boggling.
Pronoun/Antecedent
Like nouns, pronouns can be singular or plural. Pronouns must agree in number with their antecedents (the word the pronoun refers back to): a singular antecedent requires a singular pronoun.
The president of the board tendered his resignation. [his is the pronoun referring back to the antecedent president.]
Multiple antecedents require a plural pronoun.
The members of the board tendered their resignations. [their (plural) is the pronoun referring back to the antecedent members.]
A pronoun referring back to singular antecedents connected by or or nor should be singular.
Neither Sean nor Terry made his quota.
But a pronoun referring to a plural and a singular antecedent connected by or or nor should be plural.
Neither Sean nor the twins made their quotas.