They are watching TV.
Are they watching TV?
They aren't watching TV.
We have been studying here for 2 years.
Have we been studying here for 2 years?
We haven't been studying here for 2 years.
Sometimes we go to the cinema.
Do we go to the cinema sometimes?
We don't go to the cinema.
She has already left.
Has she already left?
She hasn't left yet.