It does not have legs.
It doesn’t have legs.
They are not dogs.
They’re not dogs. They aren’t dogs.
It is not raining.
It isn’t raining.
They do not have arms.
They don’t have arms.
They do not have feet.
They don’t have feet.
He should not fly.
He shouldn’t fly.
No, you should not.
No, you shouldn’t.
No, I did not.
No, I didn’t.
No, I do not.
No, I (don't).
No, I can not.
No, I (can't).