单项选择题
Diesel engine valve springs function to （）
A.hold the valves open B.keep the valves off their seats until the exhaust stroke is completed C.close the valves D.open inlet valves when the air injection cycle begins
单项选择题 Worn diesel engine intake valve guides can result in （）
单项选择题 If a diesel engine runs roughly, which of the systems listed is most likely to be at fault?（）
单项选择题 Excessive piston ring wear in a diesel engine will cause（）
