单项选择题
A.hydraulic pumps B.valves C.hydraulic cylinders D.hydraulic motors
（） are used for cargo handling.A.CranesB.Mooring winche...
单项选择题（） are used for cargo handling.
A.Cranes B.Mooring winches C.Windlasses D.Foreman
In a hydraulic system, （） are used to protect the syste...
单项选择题In a hydraulic system, （） are used to protect the system from over pressure.
A.stop valves B.check valves C.safety valves D.reducing valves
A hydraulic motor may be driven by （）.A.an electric mot...
单项选择题A hydraulic motor may be driven by （）.
A.an electric motor B.a diesel engine C.a compressor D.oil
