If the verb is the simple present or past tense of be (am, is, are, was, were), add not after the verb.

For simple present-tense verbs other than be, use do or does plus not before the base form of the verb.

For simple past-tense verbs other than be, use did plus not before the base form of the verb.

In a verb phrase consisting of one or more helping verbs and a present or past participle (is watching, were living, has played, could have been driven), use the word not after the first helping verb.

NOTE: English allows only one negative in an independent clause to express a negative idea; using more than one is an error known as a double negative.