单项选择题
A.prevent excessive cylinder liner wear
B.reduce friction losses in the engine
C.seal the space between the piston and the liner
D.limit upward flow of lube oil into the combustion space
单项选择题 Modern marine diesel engines using mechanical fuel injection, operate on a combustion cycle which is（）
单项选择题 The function of the piston compression rings used in a diesel engine is to （）
单项选择题 What determines the number of events occurring in a cycle of operation in an internal combustion engine?（）