We form negative statements with not or n’t after be, modal and auxiliary verbs . n’t is the contracted form of not. In informal language we can add n’t, without a space, to be, to modal verbs (except may) and to auxiliary verbs (do and have). The negative contracted form of will is won’t. The uncontracted form of can + not is cannot.
Jan isn’t coming. She’s not feeling very well.
She might not be joking. It could be true.
They don’t go to school on Wednesday afternoons.
Living in a small flat does not make it easy to have pets.
I hadn’t decided whether to take the train or go in the car.
They can’t be hungry again. They’ve only just eaten.
We use not or n’t to form negative questions. When there is no modal verb or be, we use auxiliary verb do + n’t (don’t, do not, doesn’t, does not, didn’t):
Won’t we able to see the film?
We use do + not or don’t + the base form of a verb to form negative orders or commands:
Do not open until instructed.
Don’t take the car. Go on your bike.