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單項(xiàng)選擇題

In （） pump a closed discharge valve will not cause excessive pressure to build up.

A.gear
B.vane
C.screw
D.centrifugal

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單項(xiàng)選擇題

Centrifugal pumps are non-positive and a fairly （） unit.

A.low pressure
B.low discharge
C.low speed
D.high pressure

單項(xiàng)選擇題

Gear pumps are （） type because they discharge a near constant amount of liquid regardless of pressure.

A.positive displacement
B.non-positive displacement
C.mixed-flow
D.axial-flow

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