1. Why has he stopped?
2. Is looking. Hasn't found
3. Is
4. Are you studying
5. They have just given
6. Is knitting
7. Have you had; don't eat
8. Are planting
9. Are you going
10. Has found; is giving
11. Have you been
12. Have you seen
13. Are you looking
14. Is looking forward
15. Is going; Isn't going
16. Has Mike left
17. Have they paid
18. Have you known
19. Makes