单项选择题
A.rather than
B.other than
C.in addition that
D.except for
单项选择题 Oil water separators are used to ensure that ships dont discharge oil when pumping out （）.
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.
单项选择题 High-speed rotation in a centrifugal purifier can produce a force （） the force of gravity.