The pollution problem here seems to get more and more serious.----Yes.Somethine___about it.A has doneB must be doneC is doingD was done回答并给我简单的讲讲.

问题描述:

The pollution problem here seems to get more and more serious.----Yes.Somethine___about it.
A has done
B must be done
C is doing
D was done
回答并给我简单的讲讲.

B must be done
一定要采取措施