单项选择题
A.air bubbles in the sight glass
B.any leaks in the system
C.over-travel in the rudder angle indicator
D.lost motion in the rams
单项选择题 Excessive air leakage into the suction side of a centrifugal pump would be indicated by which of the following operational problems?（）
单项选择题 Increasing the speed of a centrifugal pump will result in an increase in its capacity Another means of increasing the capacity of a centrifugal pump is to increase the （）.
单项选择题 If the discharge valves on a refrigeration compressor are leaking badly, the compressor should （）.