阶段曝气法的特点包括（）。 A.曝气池混合液中污泥浓度沿池长逐

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问题多项选择题

阶段曝气法的特点包括（）。

A.曝气池混合液中污泥浓度沿池长逐步降低

B.供气利用效率高，节约能源

C.曝气池停留时间较长

D.二沉池固液分离效果较差

答案

参考答案：A, B

选择题

——Is there any possibility______you could pick me up at the airport?

——No problem.

A．when

B．that

C．whether

D．what

选择题

Schools across China are expected to hire 50,000 college graduates this year as short-term teachers, almost

three times the number hired last year, _____ reduce unemployment pressures. [ ]

A. help

B. to have helped

C. to help

D. having helped