what are the rules of subject verb agreement ?

Rules of subject verb agreement:-

1. Use verbs that agree with a subject, not with a noun that is part of a modifying phrase or clause between verb and subject:

The pot of eggsisboiling on the stove.

2. Use singular or plural verbs that agree with the subject, not with the complement of the subject:

My favorite type of movieiscomedies, but Comediesaremy favorite type of movie.

3. Use singular verbs with singularindefinite pronouns— each, the -bodies, -ones, and -things (anybody,everyone,nothing), and the like:

Neitheriscorrect. (And, just as inrule number1, the presence of a modifier is irrelevant: Neither of themiscorrect.)

4. Use plural verbs with plural indefinite pronouns:

Many outcomesarepossible.

5. Use singular verbs with uncountable nouns that follow an indefinite pronoun:

All the paintisdried up.

6. Use plural verbs with countable nouns that follow an indefinite pronoun:

All the nailsarespilled on the floor.

7. Use plural verbs with compound subjects that includeand:

The dog and the catareoutside.

8. Use plural verbs or singular verbs, depending on the form of the noun nearest the verb, with compound subjects that includenororor:

Either the dog or the catsareresponsible for the mess. (Either the cats or the dogisresponsible for the mess is also technically correct but is awkward.)

9. Use singular verbs with inverted subjects that include singular nouns:

Whyismy hat outside in the rain?

10. Use plural verbs with inverted subjects (those beginning with the expletivethererather than the actual subject) that include plural nouns:

Thereareseveral hats outside in the rain.

11. Use singular or plural verbs withcollective nounsdepending on meaning:

His staffisassembled, but Staffareasked to go to theconference roomimmediately. (In the first sentence, the emphasis is on the body of employees; in the second sentence, the focus is on compliance by each individual in the body of employees.)

12. Use singular verbs for designations of entities, such as nations or organizations, or compositions, such as books or films:

TheUnited Nationsisheadquartered in New York.

13. Use singular verbs for subjects plural in form but singular in meaning:

Physicsismy favorite subject.

14. Use singular or plural verbs for subjects plural in form butplural or singularin meaning depending on the context:

The economics of the situationarecomplicated, but Economicsisa complicated topic.

15. Use plural verbs for subjects plural in form and meaning:

The tweezersarein the cupboard.

16. Use plural verbs in constructions of the form one of those (blank) who . . .:

I am one of those eccentrics whodonot tweet.

17. Use singular verbs in constructions of the form the only one of those (blank) who . . .:

I am the only one of my friends whodoesnot tweet.

18. Use singular verbs in constructions of the form the number of (blank) . . .:

The number of people herebogglesthe mind.

19. Use plural verbs in constructions of the form a number of (blank) . . .:

A number of people heredisagree.

20. Use singular verbs in construction of the forms every (blank) . . . and many a (blank) . . .:

Every good boydoesfine; Many a true wordisspoken in jest.