1. were watching/failed

2. has changed/came

3. have spent/got

4. has

5. comes

6. was being

7. were you doing/rang

8. haven't seen

9. will come

10. had worked

11. discovered

12. are singing

13. Have...received

14. have...been

15. has asked

16. was watching

17. had done/went

18. is coming

19. haven't talked

20. felt/was doing

21. haven't seen

22. has been

23. have never seen

24. had met

25. did

26. have ever read

27. will come

29. own

30. were calling

31. has seen

32. have seen

33. have met

34. had left/became

35. have seen

36. have ever met

37. was

38. haven't lived

39. have never forgotten/had just told

40. are prepapring

41. stayed/rode/had borrowed

42. told/had visited

43. has worked

44. had worked

45. build/fly

46. lost

47. hasn't smoked

48. arrived/had just gone

49. have .... been

50. Have...received

@gaukind2008

1. were watching...failed

2. has changed...came

3. have spent...got

4. has

5. comes

6. was being

7. were you doing...rang

8. haven't seen

9. will come

10. had worked

11. discovered

12. are singing

13. Have...received

14. have...been

15. has asked

16. was watching

17. had done...went

18. is coming

19. haven't talked

20. felt...was doing

21. haven't seen

22. has been

23. have never seen

24. had met

25. did

26. have ever read

27. will come

29. own

30. were calling