18. “If not us, who? If not now, when?” These two questions are used as a ( ).

56、The computer can be programmed to ( ) a whole variety of tasks.

55、During the famine, many people were ( ) to going without food for days.

54、( ) is not a serious disadvantage in life.

53、You needn't worry ( ) regards the cost of the operation.

52、Barry had an advantage over his mother ( ) he could speak French.

51、He was ( ) to tell the truth even to bis closest friend.

50、The patient's progress was very encouraging as he could ( ) get out of bed without help.

49、( ) I sympathize, I can't really do very much to help them out of the difficulties.

48、Intellect is to the mind ( ) sight is to the body.

47、There is no doubt ( ) the company has made the right decision on the sales project.