Definition: The use of verb according to the number and person of a subject in a sentence is called Subject-Verb Agreement.
Rules of Subject-Verb Agreement:
I. General Rules:
1. Singular verb is used for Singular Subject.
2. Plural verb is used for Plural Subject.
3. First Person Singular Subjects take singular verb and Plural Subjects take plural verb.
4. Second Person Singular and Plural Subjects both take plural verb.
5. Third Person Singular Subjects take singular verb and Plural subjects take plural verb.
Note: I is used as a singular subject, but both singular and plural verb is used for it.
Ex - I am a teacher.
s.v.
I have a cycle.
p.v.
II. Special Rules:
1. Suppositional Sentences generally start with if, as if, as though, if only, suppose, I wish, We wish, He wishes, She wishes always take Plural Verb 'Were'.
Ex - I wish Manisha were my wife.
If he were my boss, he would suspend me.
2. Two singular nouns joined with 'and', take plural verb.
Ex - A boy and a girl love each other.
John and Robert have done well in the examination.
3. Two subjects(Nouns) joined with and but referring to one idea, same person, same thing, take singular verb.
or
When pairing words like - bread and butter, rice and curry, hammer and sickle, slow and steady, truth and honesty, horse and carriage, crown and glory, rise and fall, coming and going, screaming and shouting, age and experience, eggs and bacon, ham and eggs, long and short, sum and substance, bag and baggage etc. used as a subject in a sentence, singular verb is used.
Ex - Bread and butter is my favourite breakfast.
Rice and curry is a popular dish.
Note: If two singular uncountable nouns joined with 'and', and used as a subject of a sentence then it refers to a class and Plural Verb is used for it.
Ex - Time and tide wait for none.
Fire and water do not agree.
4. If two Singular nouns joined with 'and', and there is articles or possessive adjectives before the first noun, then it refers to same person and singular verb is used for it.
Ex - The Principal and Secretary was there.
My uncle and guardian has come to see me.
5. Two singular nouns joined with 'and', and there is articles or possessive adjectives before both the nouns, Plural verb is used.
Ex - The Principal and the Secretary were there.
My uncle and my guardian have come to see me.
6. If two Adjectives joined with 'and' are used before a common noun and there is an indefinite article(a/an) before the first adjective, singular verb is used.
Ex - A black and white cat is mewing.
7. If two Adjectives joined with 'and' are used before a common noun and there is an indefinite article(a/an) before both the adjectives, plural verb is used.
Ex - A black and a white cat were mewing.
8. Each/every/either/neither + singular countable noun = singular verb.
Ex - Each boy was handsome.
Either pen writes well.
9. Each of/either of/neither of + plural noun/plural pronoun = Singular verb.
Ex - Each of these four pens is red.
Neither of you knows English.
10. Two subjects joined with or, nor, either....or, neither...nor, not only ... but also take verb according to the second subject.
Ex - He or I am to blame.
Neither Shyam nor his friends were innocent.
11. Two subjects joined with 'with' or 'as well as', take verb according to the first subject.
Ex - I with my guards was going to the market.
You as well as your puppy were coming to Shyam.
