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單項(xiàng)選擇題

The refrigerant leaves the evaporator of a refrigeration system as a low pressure （）.

A.sub-cooled liquid
B.high temperature liquid
C.oil saturated liquid
D.superheated vapor

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單項(xiàng)選擇題

When operating with a negative suction head, which of the following types of pumps will require priming?（）

A.Reciprocating
B.Centrifugal
C.Rotary
D.Gear

單項(xiàng)選擇題

The discharge rate or capacity of a centrifugal pump will vary directly as the （）.

A.change in the impeller diameter
B.square of the impeller radius
C.cube of the impeller diameter
D.impeller efficiency for large changes in its size