单项选择题
A.decreasing the amount of valve overlap
B.preheating the air intake
C.after-cooling the intake air
D.preheating light fuel
单项选择题 Which of the devices listed is installed on a diesel engine to isolate some of the crankshaft vibrations caused by rotational and reciprocating forces?（）
单项选择题 When used in conjunction with a turbocharger, the main function of an after-cooler is to （）
单项选择题 One of function of diesel engine lubricating oil is to （）