单项选择题
If a diesel engine rotates slowly when cranked, but does not fire, the（）
A.fuel control rack had admitted excessive fuel B.engine speed does not match the fuel rack setting C.engine has failed to reach its firing speed D.starter pinion and ring gear contact is not correct
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（）
单项选择题 Engine operating conditions may be indicated by the color of the exhaust smoke.Black smoke could indicate（）
