单项选择题
A substantial increase in crankcase pressure could be an indication of （）
A.excessive lube oil pressure B.the proper seating of new rings C.a worn cylinder liner D.a malfunctioning cylinder relief valve
单项选择题 Scuffed cylinder liner wearing surfaces in a diesel engines can result from （）
单项选择题 Exhaust pipes for separate diesel engines can be combined only when （）
单项选择题 An increase in crankcase pressure generally indicates（）
