51. In the meantime， the question facing business is whether such research is _____ the costs.

　　A. worth

　　B. worth of

　　C. worthy

　　D. worthwhile

　　正确答案是

　　52. In the preface _____ the book， the old scholar attaches great importance to practicalness.

　　A. to

　　B. for

　　C. about

　　D. of

　　正确答案是

　　53. In this experiment， they are wakened several times during the night， and asked to report what they _____.

　　A. had just been dreaming

　　B. have just been dreaming

　　C. are just dreaming

　　D. had just dreamt

　　正确答案是

　　54. In this factory the machines are not regulated ______ but are jointly controlled by a central computer system.

　　A. independently

　　B. individually

　　C. irrespectively

　　D. irregularly

　　正确答案是

　　55. It _____ five years since the famous singer left her hometown.

　　A. was

　　B. is

　　C. has passed

　　D. had been

　　正确答案是

　　56. It is difficult to tell whether a man is angry or not by _____ looking at his face.

　　A. right

　　B. barely

　　C. just

　　D. hardly

　　正确答案是

　　57. It is pretty obvious that more than one person has _____ this affair.

　　A. laid a hand on

　　B. had a hand in

　　C. got the upper hand of

　　D. got into the hands of

　　正确答案是

　　58. It is reported that _____ adopted children want to know who their natural parents are.

　　A. the most

　　B. most of

　　C. most

　　D. the most of

　　正确答案是

　　59. It is strictly _____ that access to confidential documents is denied to all but a few.

　　A. secured

　　B. forbidden

　　C. regulated

　　D. determined

　　正确答案是

　　60. It makes me sick to think of his highly _____ manners.

　　A. artistic

　　B. artful

　　C. artless

　　D. artificial

　　正确答案是