单项选择题
Combustion gases formed in the cylinder of a diesel engine are prevented from blowing past the piston by （）
A.cylinder valves B.compression rings C.piston skirts D.oil rings
单项选择题 The highest loads applied to the diesel engine crankshaft main bearings are （）
单项选择题 For most diesel propulsion and generator engines, the over-speed trip device will stop the engine by （）
单项选择题 If a diesel engine is smoking excessively under load, the cause could be （）
