The verb of a sentence must agree with the simple subject of the sentence in number and person. Number refers to whether a word is singular (child, account, city, I) or plural (children, accounts, cities, we). Person refers to whether the word denotes a speaker (I, we are first person), the person spoken to (you is second person), or what is spoken of (he, she, it, they; Gary, college, taxes are third person).
Third person singular
Choosing verbs to agree with first and second person subjects is not usually much of a problem, but a peculiarity of third person singular verbs causes some students, especially ESL students, some confusion when working with third person singular subjects.
It matters whether a subject in the third person is singular or plural because the verb form for third person singular often differs from other verb forms. For most third person singular verbs, add an s to the root form of the verb: sit + s = sits, the third person singular form. (Be careful-while an s on a noun usually denotes a plural, an s on a verb does not make the verb plural.) Examples of how the verb form changes in third person singular follow; notice that even irregular helping verbs (to have, to be, to do) add an s -- has, is, was, does -- in third person singular:
|Third person singular (he - she - it)||Third person plural (they)|
|is sitting||are sitting|
|was sitting||were sitting|
|has sat||have sat|
|has been sitting||have been sitting|
|does not sit||do not sit|
|doesn't sit||don't sit|
Thus, Olivia sits, Phong sits, the college president sits in her office, and the remote control sits on the table. When Olivia and Phong get together, however, they sit; the college trustees sit.
Only the simple subject
The verb must agree with its simple subject -- not with the description or explanation of the subject; ignore the descriptions and explanations. If the simple subject is singular, use the singular form of the verb. If the simple subject is plural, use the plural form of the verb. (For more about subjects, see the TIP Sheet Parts of Sentences: Subject, Verb, Object, Complement. For tips on how to use prepositional phrases to help identify the subject, see Prepositions and Prepositional Phrases.)
The pink and red flowers in the tall vase have wilted.
The old table that my parents gave us needs a coat of paint.
The back wheels of the car you borrowed are wobbling.
The verb must agree with its simple subject -- not with the subject complement. The subject and its complement are not always both singular or both plural. Even if one is singular and the other plural, the verb agrees with the subject:
His only hobby is his pigeons.
Her parents are her sole support.
A compound subject joined by and is plural and takes a plural verb form:
Olivia and Phong are looking for the remote control. (They are looking.)
The verb for compound subjects joined by or or by (n)either...(n)or agrees with the subject nearer to the verb:
Olivia or Phong has the responsibility to make the video presentation. (He has.)
Neither Phong nor Olivia knows if the board will be pleased. (She knows.)
The college president or the trustees interview all the candidates. (They interview.)
The trustees or the president often asks for a second interview. (He or she asks.)
Relative clauses begin with the relative pronouns who, that, or which and contain a verb separate from that of the independent clause. The verb in a relative clause agrees in person and number to the word -- the person or thing -- to which the relative pronoun refers:
Most instructors appreciate students who ask good questions.
The student who asks a lot of questions is a valuable asset to a class.
The logic class, which is known to be difficult, nevertheless attracts a certain type of student.
The classes, which are held in the fall, usually fill up fast.
Verb preceding the subject
In questions, the subject follows the verb, but the subject still determines the person and number of the verb:
Where in the house are the medicines kept? (They are kept.)
Why doesn't the soup have any noodles? (It does have.)
Under which tree do the mushrooms grow? (They do grow.)
In sentences that begin with a construction such as here is or there are, the subject follows the verb but still determines the person and number of the verb:
Here is the famous flea circus. (It is here.)
Here are the famous fleas. (They are here.)
There is a mouse in the attic. (It is there.)
There are mice in the attic. (They are there.)
Indefinite pronoun subjects
Some indefinite pronouns are always singular, and some are always plural. (Some can go either way; for more on indefinite pronouns, see the TIP Sheets Pronouns and Pronoun Reference, or see a writers' guide such as SF Writer.)
Some indefinite pronouns are always singular no matter how much you feel that words like everyone are plural. They require the third person singular verb form:
Nobody knows her.
Has anyone asked?
Everyone says so.
Each gets a ticket.
One uses a hammer.
Another has arrived.
Other indefinite pronouns are always plural and require a plural verb form:
Several work here.
Many have done it.
Few believe it.
Both were yellow.