An adverb modifies a verb. The word not is an adverb. Not is not a verb.
Bob did not finish his homework.
In this sentence, it looks like not is part of the verb – did not finish.
However, not is an adverb telling more about how the homework was finished – it was not finished.
The word not is an adverb that tells more about the action.
It’s your turn. Write a sentence where the adverb not helps to modify the verb.