单项选择题
A.improper fuel rack positing
B.lengthy exhaust valve duration
C.extend operation at light load
D.excessively early injection timing
单项选择题 One end of a cylinder for a medium or high-speed diesel engine is sealed by the piston and rings, the other end is sealed by the （）
单项选择题 Which of the diesel engine components listed increase air density and helps to improve engine operating efficiency?（）
单项选择题 Lube oil in the fresh water cooling system of a diesel engine may result from a （）