单项选择题
In a purifier changing to a gravity disc with larger hole diameter will move the interface towards the （）.
A.bowl periphery B.bowl center C.upper surface D.lower surface
单项选择题 In a marine diesel engine the oil sump is （）.
单项选择题 In a general oil cooler circulated by sea water, the oil is at a higher pressure, the result being that any leak in the cooler will mean a loss of （）.
单项选择题 In a four-stroke engines the camshaft rotates at （）.
