单项选择题
A.reciprocating pump B.gear pump C.centrifugal pump D.vane pump
Under centrifugal pumps are the volute, diffuser, mixed...
单项选择题Under centrifugal pumps are the volute, diffuser, mixed-flow, axial flow and （） or regenerative types.
A.reciprocating B.hydraulic C.turbine D.vane
Domestic water pump is started automatically by （） whic...
单项选择题Domestic water pump is started automatically by （） which operates as the water level falls to a predetermined level.
A.a level controller B.a temperature switch C.a pressure switch D.a floating ball
In cargo crane, （） for lifting the load.A.a hoisting mo...
单项选择题In cargo crane, （） for lifting the load.
A.a hoisting motor B.a luffing motor C.a mooring motor D.a slewing motor
