单项选择题
A.in series B.in parallel C.either A or B D.None of the above is tree
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.（2）and（3） D.（1），（2）and（3）
Which of the following will be the advantage of a centr...
Which of the following will be the advantage of a centrifugal pump as compared with a reciprocating pump?（） (1) Its discharge is continuous (2) It has no internal valves (3) Upon accidental closing of discharge valve, excessive pressure will not build up
A.（1），（2） B.（2），（3） C.（1），（2），（3） D.（2）only
The pipe friction and the resistance will （） as a resul...
单项选择题The pipe friction and the resistance will （） as a result of an increase in the amount of fluid flowing through the system.
A.reduce B.rise C.raise D.fall
