循环机油压低的原因有（）。
A、油位低
B、油管堵塞
C、油温高
D、连杆与十字头间隙小
参考答案：A, B, C
Do you know what ______?[ ]
A. his favourite song is
B. is his favourite song
C. his favourite song
D. his most favourite song is
对于不允许排空介质气体的压缩机，防止喘振的手段是（）。
A.关小压缩机入口阀
B.关小压缩机出口阀
C.增加压缩机转速
D.打开压缩机出口旁路阀，将出口气体一部分返回到入口端
