单项选择题
If the engine （） for a long period, there will be a danger of frost.
A.must to stand inoperative B.has to stand inoperative C.must be stood idle D.will stand idle
单项选择题 If the atomizer holes are enlarged beyond the makers recommended size, the atomizer must be （）.
单项选择题 If diesel oil in this tank is used, the （） of the oil must not exceed 120 degree F.
单项选择题 Of a kind of liquid is used to cool the diesel engine, it is invariably called （）
