单项选择题
What preventative maintenance should be done frequently to diesel engine starting air receivers?（）
A.Drain the accumulated moisture B.Test the relief valves C.Watch the temperature to prevent fluctuations in pressure D.Clean the interior to remove oil and foreign matter
单项选择题 Crank web deflection readings will give a positive indication of （）.
单项选择题 A decrease in the flash point of diesel engine lube oil indicates the lube oil has become （）.
单项选择题 The emulsion of the oil is mainly caused by （）.
