单项选择题
A diesel engine may be hard to start if the （）
A.air intake is restricted B.engine is cranked too fast C.vibration dampener is faulty D.exhaust back pressure is low
单项选择题 If a diesel engine rotates slowly when cranked, but does not fire, the（）
单项选择题 When starting air is admitted, a diesel engine turns over very slowly without firingThe cause may be （）
单项选择题 Black smoke exhausting from a diesel engine indicates（）
