John has been writing an essay for 6 hours.

I have been waiting here for 20 minutes.

We have been preparing for the exam since morning.

Kate has been playing the piano since 9 a.m.

She has been using my car again.

John hasn't been writing an essay for 6 hours.

I haven't been waiting here for 20 minutes.

We haven't been preparing for the exam since morning.

Kate hasn't been playing the piano since 9 a.m.

She hasn't been using my car again.

Has John been writing an essay for 6 hours?

Have I been waiting here for 20 minutes?

Have we been preparing for the exam since morning?

Has Kate been playing the piano since 9 a.m?

Has she been using my car again?