单项选择题
A.facilitate the installation of piston rings
B.allow for the expansion of the piston during operation
C.prevent crankcase vapors from entering the combustion chamber
D.reduce wearing of the upper cylinder liner
单项选择题 The opening of an exhaust valve on a modem, large, low-speed, main propulsion diesel engine may be actuated by （）.
单项选择题 In a diesel engine, excessive cylinder liner wear will cause （） (1) increased blow-by (2) wear between the piston ring and groove
单项选择题 Engine displacement is equal to the cylinder （）.