54. The terrorists might have planted a bomb on a plane in Athens, set to ______ when it arrived in New York.

　　A) go off

　　B) get off

　　C) come off

　　D) carry off

　　55. We should be able to do the job for you quickly, ______ you give us all the necessary information.

　　A) in case

　　B) provided that

　　C) or else

　　D) as if

　　56. The younger person's attraction to stereos cannot be explained only _____ familiarity with technology.

　　A) in quest of

　　B) by means of

　　C) in terms of

　　D) by virtue of

　　57. Attempts to persuade her to stay after she felt insulted were ______.

　　A) in no way

　　B) on the contrary

　　C) at a loss

　　D) of no avail

　　58. By signing the lease we made a _______ to pay a rent of '150 a week.

　　A) conception

　　B) commission

　　C) commitment

　　D) confinement

　　59. To prevent flooding in winter the water flowing from the dam is constantly ______ by a computer.

　　A) graded

　　B) managed

　　C) conducted

　　D) monitored