English grammar rule Have part agreement

Personal pronouns are the subject of the clause, and can be in the first person (I, we), the second person (you), or the third person (he, she, it, they). They are either singular (I, you, he, she, it) or plural (we, you, they). The form of the verb must match the form of the personal pronoun.

Examples of 'Have part agreement' rule

Incorrect	They makes a happy family.
Correct	They make a happy family.
Incorrect	He paint the house when it look shabby.
Correct	He paints the house when it looks shabby.