单项选择题
A.contaminated fluid
B.pitted thrust rings
C.worn pintle bearings
D.obstructed suctions passage
单项选择题 To maintain design discharge pressure from a centrifugal pump, the design clearance must be maintained between the （）.
单项选择题 In a radial piston pump, reversal and control of fluid flow are accomplished by moving the （）.
单项选择题 Increasing the moisture content of conditioned air is known as （）.