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單項(xiàng)選擇題

A positive displacement pump is that where the volume of the pump chamber is alternately increased to （） and then decreased to （）.

A.draw the liquid in；force the liquid out
B.force the liquid out；draw the liquid in
C.suction；draw
D.deliver；outlet

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單項(xiàng)選擇題

The amount of fluid delivered by a helical pump can be regulated by （）.

A.throttling the pressure line
B.changing the speed of the rotor
C.either A or B
D.None of the above is tree

單項(xiàng)選擇題

Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? （）
(1) reciprocating
(2) rotary
(3) centrifugal

A.(1)only
B.(1)and (2)
C.(1),(2)and(3)
D.(2)and(3)