单项选择题
When starting air is admitted, a diesel engine turns over very slowly without firingThe cause may be （）
A.an obstruction in an cylinder B.water accumulation in some engine cylinders C.low starting air pressure D.low scavenge air pressure
单项选择题 Black smoke exhausting from a diesel engine indicates（）
单项选择题 Engine operating conditions may be indicated by the color of the exhaust smoke.Black smoke could indicate（）
单项选择题 A dark exhaust from a running diesel engine can be caused by （）
