What is SUBJET VERB AGREEMENT?

The basic rule states that a singular subject takes a singular verb, while a plural subject takes a plural verb.

Subject	Verb
He / She / It	is / verb + -s
We / They / You	are / verb stem
I	am / verb stem

Remember that the subject is not always the noun closest to the verb.

Example:

The number of pupils in the school is big.

Note: "school" is not the subject! Instead, "number" is the subject.

The verb to be, present (past)

Person	Singular	Plural
First	I am (was)	We are (were)
Second	You are (were)	You are (were)
Third	He, she, it is (was)	They are (were)

The verb to have, present (past)

Person	Singular	Plural
First	I have (had)	We have (had)
Second	You have (had)	You have (had)
Third	He, she, it has (had)	They have (had)

Regular verbs, e.g. work, present

Person	Singular	Plural
First	I work (worked)	We work (worked)
Second	You work (worked)	You work (worked)
Third	He, she, it works (worked)	They work (worked)

(Adapted: http://www.wordforword.se/download/VerbForm.pdf ; http://www.grammarbook.com/grammar/subjectverbagree.asp )