单项选择题
Diesel engine lube oil diluted with fuel oil is indicated by（）
A.decreased viscosity B.decreased pour point C.increased flash point D.increased viscosity
单项选择题 The primary purpose of oil control rings on a diesel piston is to（）
单项选择题 The purpose of compressing the air within the cylinder of a diesel engine is to （）
单项选择题 A smoking exhaust from an operating diesel engine could be caused by （）
