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單項(xiàng)選擇題

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

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單項(xiàng)選擇題

A hydraulic motor may be driven by （）.

A.an electric motor
B.a diesel engine
C.a compressor
D.oil

單項(xiàng)選擇題

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

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