单项选择题
A.breaking up solid matter into fine particles
B.precipitating non-decomposed waste in a collection tank
C.chemically adjusting the sewage ph to 7-0
D.eliminating bacterium coli from the sewage
单项选择题 Which of the equipment listed is most effective in processing bilge slops for overboard discharge?（）
单项选择题 If you heard a ‘crackling’ noise in centrifugal pump, the most probable cause of the problem would be（）
单项选择题 The valve which is most suited for regulating the flow through a pipeline is a （）