单项选择题
The primary purpose of oil control rings on a diesel piston is to（）
A.provide a reservoir for cylinder lubrication B.pump oil into the combustion space for cylinder cooling C.prevent excessive lubricating oil consumption D.allow hydraulic oil film formation on the cylinder
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 （）
单项选择题 What is commonly used to create turbulence in a diesel engine combustion system?（）
