污、废水为什么要脱氮除磷?叙述污、废水脱氮、除磷的原理。
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Toula’s elder sister is confused with her culture identity.
A. 对
B. 错
Ian has a big family.
A. 对
B. 错
Toula’s extended family celebrate Christmas together.
A. 对
B. 错
Ian believes that different backgrounds would not be an insurmountable problem in their relationship.
A. 对
B. 错