单项选择题
A.throttling the pressure line B.changing the speed of the rotor C.either A or B D.None of the above is true
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) ejector (2) screw (3) centrifugal
A.(1)only B.(1)and(2) C.(1),(2)and(3) D.(2)and(3)
In （） pumps a closed discharge valve will cause burstin...
单项选择题In （） pumps a closed discharge valve will cause bursting discharge pressure.
A.centrifugal B.plunger C.injector D.water
The volute pump is one in which the impeller （）.A.disch...
单项选择题The volute pump is one in which the impeller （）.
A.discharges into a gradually widening channel B.has stationary diffuser vanes C.produces no kinetic energy D.All of the above are true
