5. what are they doing now? (present progressive) they are working in the reading room.(present progressive) they have been working there for three hours already. (present perfect progressive)
9. have you found your notebook? (present perfect) no! I'm still looking for it. (present progressive) I have been looking for it for two hours(present progressive), but haven't found it yet.(present perfect)
10. you have been playing with a ball for three hours already. (present perfect progressive) go home and do your homework
15. what are you doing?(present progressive) I'm reading. (present progressive)I have been reading for two hours already.(present perfect progressive) I have already read sixty pages. (present perfect)
20. come along, Henry, what are you doing now? (present progressive) I'm waiting for you for a long time (present progressive)
