60. I can't use your pen, ___ there is no ink in it.　　　　 A. for　　 B. when　 C. if　　 D. whether　

59. Things have changed a lot ____ I wrote to you last time.

A. when　　　　　　 B. since　　　　 　 C. as　　　 　　 D. before

58. ___ he came to study in the university, he has made much progress in the study of English.

A. While　　　　　　 　　 B. When　　　　　　 C. Since　　　　　　 D. After

57. I'll come and see you _____ I go to the countryside.

A. while　　　　　　 B. when　　　　　 .　 C. as soon as　　　　 D. before

56. Don't try to get off the bus ____ it has stopped.

A. while　　　　　　 B. as　　　　　　　　 C. since　　　　　　 D. before

55. He will tell you about it ____ you get there.　　　

A. while　　　 B. as　　　 C. when　　　 D. /

54. We shall go ____ you are ready. 　

A. while　　 　　 B. as soon as　　　 C. as　　　 D. since

53. It has not been decided ____ they will leave.

A. why　　　　　　　 B. when　　　　　　 C. which　　　　　　 　　 D. what

52. The trouble is ____ we can not find such an expert.

A. why　　　　　　 B. that　　　　　　 C. where　　　　 　 D. /

51. I am sure ____ you said is true.　　　　

A. what　　　 B. that　　　 C. which　　 D. who