单项选择题
A.between the suction and discharge B.below the liquid supply C.above the liquid supply D.any of the above
Which of the following pumps are self-priming, and can ...
Which of the following pumps are self-priming, and can deal with liquid from a level below the pump? （） (1) reciprocating (2) vane (3) gear
A.（1）only B.（1）and（2） C.（1），（2）and（3） D.（2）and（3）
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 positive displacement pump is that where the volume o...
单项选择题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.increased；decreased B.decreased；increased C.decreased；decreased D.increased；increased
