单项选择题
Under normal conditions, the main source of crankcase oil contamination is attributed to （）
A.metal particles loosened by wear B.air when air cleaners are not used C.condensation of water vapors D.breakdown of the lubricating oil by dilution
单项选择题 Valve cages are used on some large diesel engines to （）
单项选择题 If the jacket water temperature rises rapidly above normal in a diesel engine, you should FIRST （）
单项选择题 Which of the following conditions can cause excessive lube oil consumption in a diesel engine?（）
