Is he watching TV?
Yes, he is.
Are they watching TV?
No, they aren't
Are they eating?
No, they aren't
Is he playing the guitar?
No, he isn't.
Are they listening to music?
Yes, they are.
Is she playing the guitar?
Yes, she is.
Are they doing homework?
Yes, they are.
Are they listening to music?
No, they aren't
Are they playing the guitar?
Yes, they are.