11. It may be necessary to stop__________________________(每隔…时间) in the learning process and go back to the difficult points in the lessons.
　　
　　12. The mad man was put in the soft-padded cell lest he ______________(伤害自己).
　　
　　13.Jean did not have time to go to the concert last night because she was_______________(忙着准备) her examination.
　　
　　14. The ship’s generator broke down and the pumps____________________(不得不用手工操作) instead of mechanically.
　　
　　15. Why didn’t you tell me you could me the money? I___________________________ (本来不必从银行借钱的).
　　
　　

　　答案

　　11. at intervals
　　
　　12. injure himself
　　
　　13. busy preparing for
　　
　　14. had to be operated manually
　　
　　15. needn’t have borrowed it from the bank.