31. DADCC　 36. ABDDC　　 41. CDBCB　　 46. BDDBC

1. BADDD　　 6. DCDDD　　 11. ADBDC　　 16. BCBCB　　 21. BDDAA　　 26. ABBAD

50. I thought Jim would say something about his school report, but he ______ it.

　 A. doesn’t mention　　　　　 B. hadn’t mentioned　　　　　　　 C. didn’t mention　　　　　　　　　 D. hasn't mentioned

Key to “时态和语态50题”:

49. ---I’m sorry, but there’s no smoking on this flight.　 ---Oh, I ______ that. Sorry, I won’t again.

　 A. don’t know　　　　　　　　 B. didn’t know　　　　　　　　　　　 C. won’t know　　　　　　　　　　　 D. haven’t known

48. It is when the plane ______ that you’d better find out at the booking office.

　 A. would take off　　　　　　 B. had taken off　　　　　　　　　　 C. was taking off　　　　　　　　　 D. is taking off

47. The baby is generally healthy, but every now and then he ______ a cold.

　 A. has caught　　　　　　　　　　　　　　 B. is catching　　　　　　　　　　　　 C. will catch 　　　　　　　　　　　　 D. does catch

46. ---Each of the students, working hard at their lessons, ______ the book.　 ---So have I.

　 A. is reading　　　　　　　　　　 B. has read　　　　　　　　　　　　　　 C. reading　　　　　　　　　　　　　　　 D. reads

45. ---I dropped in at your house at about ten last night, but you weren’t in.

　 ---I ______ regular exercises at the club.

　 A. did　　　　　　　　　　　　　　　 B. was doing　　　　　　　　　　　　　 C. had done　　　　　　　　　　　　　　 D. have been doing

44. ---Who’s the man over there?　 ---It’s Jack.　 ---Oh? ______ in Italy.

　 A. I think he’s　　　　　　　　　 B. I’ve thought he’s been 　　 C. I thought he was　　　　　　　　 D. I’d thought he’d been

43. With the development of science, more new technology ______ to the field of IT.

　 A. has introduced　　　　　　 B. is being introduced　　　　　　 C. is introduced　　　　　　　　　　　 D. was introduced