单项选择题
To avoid scavenge fires occurring the engine timing and equipment maintenance （）.
A.should be correctly carried out B.should correctly be taken place C.should carried with care D.must to carry out with great care
单项选择题 Combustion knock can occur in the cylinders of a diesel engine under any condition permitting （）.
单项选择题 Which of the following may cause that an engine doesnt turn on starting air?（）
单项选择题 Poor combustion in a diesel engine can be caused by （）.
