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

50. Would you tell me ____ way I should take?　 A. what　　　 B. that　　 C. which　　 D. whose

49. It is quite clear ____ he won't see us.　　 A. what　　　 B. that　　　 C. why　　　 D. how

48. ___ he did it remains a secret.　　　　 A. What　　　 B. Whom　　　 C. Which　　　 D. How

47. That is not ____ I want.　　　　　 A. that　　 　 B. why　　 　　　　 C. what　　　 D. whose

46. Please write me ____ you arrive in New York.

A. as well as　　 　　　　　 B. so long as　　　　 　 C. as far as　　　　　 　 D. as soon as

45.___ I know he will stay here for half a year.

A. as soon as　　 　　　　　 B. as long as　　　　 　 C. so far as　　　　　 　 D. as well as

44. We can surely overcome these difficulties _,___ we are closely united.

A. so far as　　　　 　　 B. so long as　　　 　　 C. as soon as　　　　 　 D. as well as