单项选择题
In a diesel engine, a cylinder liner should be replaced if it is （） Ⅰ.Scuffed Ⅱ.Scored
A.Ⅰ only is correct B.Ⅱ only is correct C.both Ⅰ and Ⅱ are correct D.neither Ⅰ or Ⅱ are correct
单项选择题 Under normal conditions, the main source of crankcase oil contamination is attributed to （）
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 （）
