单项选择题
The suction - force principle of operation is a typical characteristic of （）.
A.centrifugal pumps B.jet pumps C.propeller pumps D.reciprocating pumps
单项选择题 Air leakage between the shaft and stuffing box packing in a centrifugal pump is prevented by （）.
单项选择题 Tube leaks in the distillate cooler of a two stage flash evaporator will result in （）.
单项选择题 The pressure of a liquid leaving the pump can be referred to as the （）.
