当CRH1A型动车组总风压力低于850kpa时，（）台主空气压缩机开始启动工作。
A.1
B.2
C.3
D.4
参考答案：A
The beauty of this career is that it allows us to________our interest with our work, gaining freedom
and happiness in the process. [ ]
A. combine
B. fix
C. link
D. join
中粉可以全部通过几号筛（）
A.2号
B.4号
C.5号
D.6号
E.8号
