单项选择题
In large, low-speed, main propulsion diesel engine, position ring groove wear usually occurs at the（）
A.top of the ring groove B.back of the ring groove C.bottom of the ring groove D.piston ring end clearance
单项选择题 Diesel engine blow-by is the leakage of combustion gases past the （）
单项选择题 In a diesel engine, blow-by is a result of combustion gases leaking into the crankcase past the （）
单项选择题 A centrifuge will satisfactorily remove which of the following contaminants from fuel oil?（）
