单项选择题
Diesel engine lube oil can become contaminated as a result（）
A.the water produced during combustion B.the sulfur in the fuel C.unburned fuel oil D.all of the above
单项选择题 If the firing pressures in a diesel engine are high, although the exhaust temperatures are normal, the cause may be（）
单项选择题 Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）
单项选择题 A diesel engine piston crown can crack from （）
