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单选题
The amount of fluid delivered by a centrifugal 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
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diameter of the discharge piping, with all other factors remaining the sameB
diameter of the suction piping, with all other factors remaining the sameC
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diameter of the impeller
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set the relief valveB
check the lubrication systemC
vent the pump casingD
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contaminated fluidB
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assembledD
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centrifugal pump is cheaper than reciprocating pumpB
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单选题The amount of fluid delivered by a positive displacement pump can be regulated by （）.A
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either A or BD
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单选题Why are removable sleeves installed on centrifugal pump shafts?（）A
They make it easier to replace the pump shaft packingB
They can be economically replaced as they wear outC
They can be removed when it is necessary to lighten the weight of the pumpD
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