单项选择题
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.(1)only B.(1)and (2) C.(1),(2)and(3) D.(2)and(3)
单项选择题 The amount of fluid delivered by a positive displacement pump can be regulated by （）.
单项选择题 The amount of fluid delivered by a reciprocating pump can be regulated by （）.
单项选择题 The amount of fluid delivered by a centrifugal pump can be regulated by （）.
