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單項選擇題

Some pumps use packing as sealing glandThe gland should be （）.

A.slack enough to allow slight leakage of fluid
B.slightly clocked
C.brought up tight so as not to allow any leakage
D.fitted with a relief valve

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單項選擇題

Which of the following pumps is used where a relatively high pressure and small capacity are required?（）

A.Volute pump
B.Diffuser pump
C.Regenerative pump
D.All of the above

單項選擇題

The （） pump discharges a nearly constant amount of liquid regardless of pressure.

A.mixed-flow
B.axial-flow
C.centrifugal
D.displacement