Answer:

An affirmative sentence simply states something. It is any declaration that is positive. An affirmative sentence expresses the validity of truth of an assertion. ... An affirmative or positive sentence means something is so, while a negative sentence – which is its polar opposite – means something is not so.

Explanation:

The Negation Rule: In English, in order to claim that something is not true, you form a negative sentence by adding the word not after the first auxiliary verb in the positive sentence