在活塞式压缩机中气阀是依靠（）两侧的压力差来起闭的。
A.弹簧
B.阀座
C.阀片
D.升程限制器
参考答案：C
根据下列句子中所给汉语注释，在句子右边的横线上，写出空缺处各单词的正确形式。（每空只写一词）
小题1:Which ________(部分) of the town do you live in?
小题2:Tom has the ___________(能力) to do the work.
小题3:The whole house _________（震动）during the earthquake on that day.
小题4:About 90 percent of these ______(病例) can be cured.
小题5:The plane will take off ________(不久).
______ your father happy now? Yes.[ ]
A. Do
B. Does
C. Are
D. Is
