单项选择题
A diesel engine should not be operated at low loads for long periods of time because（）
A.heavy carbon deposits will buildup on the valves and in the exhaust B.fuel dilution is increased at low load C.exhaust valves may be damaged D.all of the above
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 （）
单项选择题 The most common diesel engine fuel system problems are caused by （）.
