單項(xiàng)選擇題

Operating a rotary pump at speeds in excess of design requirements could cause（）.

A.decreased clearances between rotating parts
B.decreased slippage to the suction side of the pump
C.air binding in the discharge ports
D.erosion and excessive wear

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單項(xiàng)選擇題

A refrigeration system compressor crankcase is sweating or unusually coldThis is an indication of（）.

A.a shortage of refrigerant in the system
B.air in the system
C.an accumulation of liquid refrigerant in the crankcase
D.a shortage of oil in the crankcase

單項(xiàng)選擇題

When the desired rudder angle is attained by a typical double mm electro-hydraulic steering gear,the（）.

A.ram relief valves bypass oil to stop rudder movement
B.six-way valve shifts to the neutral flow position
C.steering pump electric motor is de - energized by the transfer switch
D.follow-up gear takes the hydraulic pump off stroke