单项选择题
A.gear B.vane C.screw D.centrifugal
Centrifugal pumps are non-positive and a fairly （） unit...
单项选择题Centrifugal pumps are non-positive and a fairly （） unit.
A.low pressure B.low discharge C.low speed D.high pressure
Gear pumps are （） type because they discharge a near co...
单项选择题Gear pumps are （） type because they discharge a near constant amount of liquid regardless of pressure.
A.positive displacement B.non-positive displacement C.mixed-flow D.axial-flow
（） are more suitable for large quantities at low pressu...
单项选择题（） are more suitable for large quantities at low pressure.
A.Reciprocating pumps B.Rotary pumps C.Centrifugal pumps D.Gear pumps
