单项选择题
The highest pressure in a diesel engine cylinder normally occurs （）.
A.at TDC B.before TDC C.after TDC D.during air starting
单项选择题 What causes diesel fuel to be ignited in the cylinder of an operating diesel engine?（）
单项选择题 The main purpose of the piston oil scraper rings is to （）.
单项选择题 Maximum horsepower of a diesel engine is attained （）.
