A screw pump belongs to () according to its working principle.
A、reciprocating pumps
B、positive displacement pumps
C、centrifugal pumps
D、centripetal pumps
A、reciprocating pumps
B、positive displacement pumps
C、centrifugal pumps
D、centripetal pumps
A、variable stroke pumps B、multistage pumps C、positive displacement pumps D、triple-ported pumps
A、variable stroke pumps B、multistage pumps C、positive displacement pumps D、triple-ported pumps