单项选择题
A.slack enough to allow slight leakage of fluid B.slightly clocked C.brought up tight so as not to allow any leakage D.fitted with a relief valve
Which of the following pumps is used where a relatively...
单项选择题Which of the following pumps is used where a relatively high pressure and small capacity are required?（）
A.Volute pump B.Diffuser pump C.Regenerative pump D.All of the above
The （） pump discharges a nearly constant amount of liqu...
单项选择题The （） pump discharges a nearly constant amount of liquid regardless of pressure.
A.mixed-flow B.axial-flow C.centrifugal D.displacement
Which of the following operating features do displaceme...
Which of the following operating features do displacement pumps bear if they are working under no-cavitation condition?（） (1) output is almost directly proportional to speed (2) they are self-priming (3) they will develop a discharged pressure equal to the resistance to be overcome, irrespective of speed
A.（1）and（2） B.（2）and（3） C.（1）and（3） D.（1），（2）and（3）
