Verb must agree with the subject in number

1)      The girl sings

2)      The girls sing

In the first sentence, the subject girl is in the singular number; so the verb sings is also in the singular.

In the second sentence, the subject girl is in the plural number, so the verb sing is also in the plural.

A verb must agree with the subject in person

I sing

He sings

The subject in both the sentences is in the singular number. But the subject in the first sentence is a pronoun of the first person, while the subject in the second sentence is a pronoun of the third person.

So we see that verbs here change in from according to the person of their subjects.

Though the verb takes the same person as its subject, it doesn’t always change in form; as

a)      I sing

b)      We sing

c)      You sing

We may now say that the verb agrees with its subject in number and person

A)    Two or more singular subjects joined by and generally take a verb in the plural; as,

Radha and her sister are here

Wheat and rice grow in India

She and I are friends

He and his father have come

B)     If two singular nouns refer to the same person or thing, the verb must be in the singular; as,

The writer and scientist is no more

My friend and guide has come

Rice and curry is liked by all

Slow and steady wins the race

C)    When a singular noun or pronoun is joined to a second noun by with or as well as, the verb is in the singular number; as,

Ravi with his friends was present

Iron as well as gold is found in India

D)    When two more subjects in the singular are joined by or, nor, either, or, neither-nor the verb is in the singular; as,

Ravi or Shekar is at fault

Either Radha or Savita was present

Neither Ravi nor his brother has succeeded

E)     But if two subjects joined by or, nor are of different number or persons, the verb must agree with the subjects nearest to it; as,

Neither he nor I am guilty

Either you or she has done this

F)     Either , neither, each, every, everyone, a little, many a, must be followed by a verb in the singular; as,

Either of these two players has cheated

Neither of the two plans is useful

Many a girl has failed in the test

Everyone knows the secret now

G)    A few, several, both, many are always followed by a verb in the plural; as,

A few of these books are still available.

Several of the shops are open today

Both the boys have failed

Many of these cows have been hurt

H)    Where the subject is the introductory `there’, the verb agrees with the real subject that follows it; as,

There is a TV in the room

There are boys in the hall

I)       When the plural noun is the name of a country or the title of the book, it takes a singular verb; as,

The United States is rich country

Gulliver’s travels is an interesting book