单项选择题
A.worn bearings and piston pins
B.slugging due to flooding back
C.too much oil in circulation
D.All of the above
单项选择题 The air charge leaving an intercooler, or after-cooler of an air compressor can be expected to be （）.
单项选择题 Before starting a reciprocating, steam-driven pump that has been idle for a period of time, you should （）.
单项选择题 When air becomes trapped in the hydraulic fluid of a steering system, the （）.