Утвердительные:
You are talking on the phone.
You're working
We are watching tv
They are playing cards
She is doing nothing
Отрицательные:
She is not working now
They are not cooking, they are doing something else
You are not joking about it
He is not solving this problem
They are not playing football
Вопросительные:
Are you working now?
Are they doing something important?
Is he watching the tv show?
Is she joking?
Is he walking home now?