往复式压缩机压缩气体的工作过程可分为膨胀、吸入、压缩和排出四个阶段。
参考答案：对
The government not only _____ the refugees (难民) houses to live in, but also _____ them with food and clothes.[ ]
A. offered; offered
B. provided; provided
C. provided; offered
D. offered; provided
长度在50m以下的电缆（）充气维护。
A.需要
B.不用
C.可充可不充
