Negative form: AM / is / are + not; if the predicate in this tense is an action verb, add don't before it, if the subject is the third person singular Don't is used to make sentences,

Negative form: AM / is / are + not; if the predicate in this tense is an action verb, add don't before it, if the subject is the third person singular Don't is used to make sentences,

He likes football.
He doesn't like football.