反硝化生物滤池的功能？
参考答案：
通过脱氮作用将污水中含氮有机物转化为氮气，去除污水中的NH4-N含量，随后处理水自流入配水井。
—We have decided to go for a picnic tomorrow, Dick.Are you going with us?
—Well, _______ you are going, so will I.
A．when
B．since
C．if
D．while
如图是禁止超车标志。
