1. When the subject is singular, the verb is singular.

The girl sings well.

2. When the subject is plural, the verb is plural.

Those boys sing well.

3. When the subjects are joined by 'and' , the verb is in plural.

The boy and the girl sing well.

4. When the subjects are connected by 'either...or', 'neither...nor', 'but', 'as well as', 'together with', 'in addition to', the verb agrees with the nearer one.

Either the boy or the girls sing well. (sing is nearer to girls which is in plural)

Either the girls or the boy sings well. (sing is nearer to boy which is in singular)

The girl together with the boy sings well.(sing is nearer to boy which is in singular)

5. When the subjects are separated by 'all but', 'both...and', the verb is in plural.

Both the girl and the boy sing well.

6. When the subject is preceded by 'each', 'every', the verb is in singular.

Every boy and girl sings well.

7. When two singular subjects refer to the same person or thing, the verb is in singular.

Mary, my good friend and neighbour, sings well.

8. When two subjects are used to express one idea, the verb may be singular.

Bread and butter is all she takes for breakfast.

9. Indefinite pronouns like 'somebody, anybody, everybody, nobody, no one', the verb is in singular.

Everybody sings well.

10. When a sentence starts with 'it', the verb is always singular.

It is you who reported the matter to Jennifer.

11. When a sentence starts with 'there, here', the verbs agrees with the subject following, not the introductory word.

There is one girl sitting alone there.

There are lots of cakes in a bakery.

12. A collective noun takes a singular verb when it means a group.

The team wins every time.

13. A collective noun takes a plural verb when it refers to the members of the group.

The team are working well together.

14. Titles of books, plays, magazines or newspapers take a singular verb.

'The merchant of Venice' is an excellent book.

15. Plural numbers take a singular verb when they are used in a sentence to mean a sum or a unit.

Three years is a long time.

16. Some nouns are plural in form but singular in meaning. They usually take a singular verb.

Physics bores me a lot. Some other examples:

Dynamic, Mathematics, Economics, Statistics, Electronics

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