单项选择题
A.many thousand times larger than B.the same as C.many thousand times smaller D.none of the above
The separation of impurities and water from （） is essen...
单项选择题The separation of impurities and water from （） is essential for good combustion of diesel engines.
A.lube oil B.fuel oil C.turbine oil D.grease
Which of the following may hardness of the boiler water...
Which of the following may hardness of the boiler water cause?（） (1) scale formation (2) tube failure (3) corrosion
A.（1）and（2） B.（1）and（3） C.（2）and（3） D.（1），（2）and（3）
The water level showing in a boiler water gauge glass i...
单项选择题The water level showing in a boiler water gauge glass is usually （） during working.
A.higher than the actual drum water level B.equal to the actual drum water level C.increasing due to steam condensation in the glass D.lower than actual drum water level
