單項(xiàng)選擇題Before the sludge in a purifier is ejected,()

A.the oil feeding is stopped and replaced by admitting flushing water
B.the flushing water feeding is stopped and replaced by admitting oil
C.the feeding of dirty oil and flushing water is stopped
D.the feeding of dirty oil and flushing water is admitted


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1.單項(xiàng)選擇題A centrifuge of which the bowl is arranged as the upper and lower parts separate discharges the sludge()

A.by opening the separator manually
B.by separating the lower part from the upper part automatically
C.by separating the upper part from the lower part automatically
D.continuously

3.單項(xiàng)選擇題The treatment of the fuel oils involves storage, heating, filtering and()

A.centrifuging
B.pressurizing
C.atomization
D.igniting

4.單項(xiàng)選擇題When anaerobic bacteria convert the sewage to an inert sludge,()

A.no oxygen is needed
B.oxygen is necessary
C.oxygen is given off
D.no gas is produced

5.單項(xiàng)選擇題Bacteria which live are said to be aerobic()

A.in the presence of oxygen
B.without oxygen
C.in the presence of nutrition
D.without nutrition