单项选择题
A.ballast water B.boiler water C.bilge water D.sewage water
（）are used to ensure that ships don’t discharge oil whe...
单项选择题（）are used to ensure that ships don’t discharge oil when pumping out oily water from any oil contaminated space.
A.Boiler B.Incinerator C.Oily water separator D.Sewage treatment unit
High-speed rotation in a centrifugal purifier can produ...
单项选择题High-speed rotation in a centrifugal purifier can produce a force （） the force of gravity.
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
