单项选择题
If the chemical analysis of a lube oil sample taken from a diesel engine indicates an increased neutralization number, the （）.
A.acidity has increased B.viscosity has decreased C.demulsibility has improved D.foaming is guaranteed to occur
单项选择题 When an auxiliary boiler is panting and emitting black smoke, you should （）.
单项选择题 With regards to a diesel engine crankcase explosion, the most violent is the（） (1) primary explosion (2) secondary explosion
单项选择题 Waterside scale in a fire-tube boiler may cause （）.
