单项选择题
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
A high rate of separation between oil and water is favo...
单项选择题A high rate of separation between oil and water is favored by （）.
A.large size of oil globule B.low temperature C.high viscosity D.high flow rate
