单项选择题
If the engine does start on air, but combustion does not immediately begin, the cause may be （）.
A.failure of the fuel pumps B.starting air pressure too low C.stop valve in air line closed D.the turning gear still engaged
单项选择题 If the engine does not start on air, it may be due to （）
单项选择题 If the engine （） for a long period, there will be a danger of frost.
单项选择题 If the atomizer holes are enlarged beyond the makers recommended size, the atomizer must be （）.
