单项选择题
Diesel engine air start system check valves are opened by （）
A.an air start cam B.cylinder compression pressure C.starting air pressure D.valve springs
单项选择题 For a diesel engine, individual cylinder performance is commonly determined by exhaust gas（）
单项选择题 Low compression pressure in a diesel engine may be the result of （）
单项选择题 Exhaust gas pyrometers are useful for（）
