50.Firms that use computers have found that the number of staff（ ）is needed for quality control can be substantially reduced.

20.“Harry was compelled to resign and to come down to London, where he set up as an army coach.” The relative clause in the sentence serves to（ ）.

19.What is the function of the present progressive in “They are always calling me by the wrong name”?

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

17.The bad news was that he could be a very dangerous personhe choose to be.

16.The woman had persuaded him to do（ ）he was hired never to do — reveal the combination for the lock on the entrance.

15.Protocol was（ ）enabled him to make difficult decisions without ever looking back.

14.Writers often coupled narration with other techniques to develop ideas and support opinions that otherwise（ ）abstract, unclear, or unconvincing.

13.Members of the Parliament were poised（ ）ahead with a bill to approve construction of the oil pipeline.

12.（ ）the attempted rescue mission, the hostages might still be alive.

11.Moving from beginning to end by order of time, narration relies on a more natural pattern of organization than（ ）.