1. have been working
2. do you walk
3. is studying
4. hasn't played
5. has she known
6. is he doing
7. have known
8. has he been learning
9. do you get
10. does she do
11. has gone
12. has ever written
13. has been watching
14. knows
15. hasn't broken
16. Do you want
17. leaves
18. has been sleeping
19. doesn't look
20. smells