18. sells (ko chắc)
20. used to ski, was broken, haven't ski
21. saw
22. Have you ever bought
23. met
24. was playing...was writing
25. bought
26. has lived
27. have already been
28. Are you planning
29. haven't had
30. looked, saw, was raining
31. had been working
32. have seen
33. have you waited
34. flew, Did you see
35. have already eaten
36. was playing
37. were you doing
38. had seen
39. were reading, was knitting, was playing, opened, came
40. has become