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单选题
A （） pump is that where the volume of the pump chamber is alternately increased to draw the liquid in and then decreased to force the liquid out.
A
injector
B
positive displacement
C
centrifugal
D
centripetal
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单选题A positive displacement pump is that where the volume of the pump chamber is alternately increased to （） and then decreased to （）.A
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单选题A positive displacement pump is that where the volume of the pump chamber is alternately （） to draw the liquid in and then （） to force the liquid out.A
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the same size as the pump suction nozzleC
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positive displacementB
ejectorC
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air compressor
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excessive pump discharge pressureC
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each fire station dischargeD
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