Don't __________ jeans to the party. [ ]
A. put on
B. wear
C. wearing
D. dress
答案:B
活塞式压缩机的机械效率等于()
A.压缩机指示功率与轴功率之比
B.压缩机摩擦功率与轴功率之比
C.压缩机指示功率与摩擦功率之比
D.压缩机摩擦功率与指示功率之比
事故