In a sentence, the subject and verb should "agree." This means the form of the verb should fit the number of subjects, single or plural. ("They go" but "she goes").

1. When the subject of a sentence is composed of two or more nouns or pronouns connected by and, use a plural verb.
For example: She and her friends are at the fair.

2. When two or more singular nouns are connected by or or nor, use a singular verb.
For example: The book or the pen is in the drawer.

3. When subject contains both a singular and a plural noun or pronoun joined by or or nor, the verb should agree with the part of the subject that is nearer the verb.
For example:  The boy or his friends run every day.
His friends or the boy runs every day.

4. Do not be misled by a phrase that comes between the subject and the verb. The verb agrees with the subject, not with a noun or pronoun in the phrase.
For example:   One of the boxes is open.
The people who listen to that music are few.
The team captain, as well as the players, is anxious.

5. The words each, each one, either, neither, everyone, everybody, anybody, anyone, nobody, somebody, someone, and no one are singular and require a singular verb.
For example:   Each of these hot dogs is juicy.
Everybody knows Mr. Jones.

6. Nouns such as civics, mathematics, dollars, measles, and news require singular verbs.
For example: The news is on at six.
BUT the word dollars is a special case. When talking about an amount of money, use a singular verb, but when referring to the dollars themselves, use a plural verb.
For example:   Five dollars is a lot of money.
Dollars are often used instead of rubles in Russia.

7. Nouns such as scissors, tweezers, pants, trousers, and shears require plural verbs because there are two parts to these things.
For example: These scissors are dull.

8. In sentences beginning with there is or there are, the subject follows the verb. Since there is not the subject, the verb agrees with what follows it.
For example:  There are many questions. -OR -There is a question.

9. Collective nouns are words that imply more than one person but that are considered singular and take a singular verb, such as: group, jury, team, committee, class, council and family.
For example: The team runs during practice.
The jury decides the condemned man's fate.

10. Expressions such as with, together with, including, accompanied by, in addition to, or as well do not change the number of the subject. If the subject is singular, the verb is too.

For example: The President, accompanied by his wife, is traveling to India.