多段式压缩机
参考答案：
压缩机自大气进气压力压缩至最终的排气压力，其压缩系分别由二次（二段）或二次以上的压缩而达成者，如高压式或超高压式空压机。
We suggest that you file a claim ______ the shipping company for all the losses incurred as a consequence of failure to ship the goods ______ Order No. 123 in time.
A．against, unless
B．for, in
C．against, in
D．against, under
DVD采用的是（）编码方法。
A.MPEG-1
B.MPEG-2
C.MPEG-3
D.MPEG-5
