单项选择题
Combustion knock can occur in the cylinders of a diesel engine under any condition permitting （）.
A.a shortened ignition delay period B.a lean fuel/air mixture C.excess fuel in the combustion chamber D.rapid vaporization of injected fuel droplets
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 （）.
单项选择题 A built-up exhaust valve is one in which （）.
