工程机械上使用的工作油主要有液压油,液力传动油和()三种。
A、齿轮油
B、机油
C、黄油
D、制动油
参考答案:D
— ______ your sister have a computer?
— Sorry. I don't think she has _______. [ ]
A. Do; it
B. Does; one
C. Do; one
D. Does; it
螺栓或螺孔滑扣,不影响设备的隔爆性能。()