单项选择题
The major cause of fuel pump and injection system problems is （）
A.improper adjustments B.contaminated fuel C.kinked fuel lines D.excessive engine vibration
单项选择题 A diesel engine should not be operated at low loads for long periods of time because（）
单项选择题 Diesel engine fuel oil contamination often results in （）
单项选择题 When a diesel engine is operate at partial load, as compared to full load ,a decrease will occur in the average （）
