—The pollution problem here seems to get more and more serious.
--Yes. Something about it.
A. must do
B. must be done
C. is doing
D. had been done
网友回答
A. must do
(答案→)B. must be done
C. is doing
D. had been done
解析：考查时态及语态.句意:这儿的污染问题单好像越来越严重.——是的，对此必须做些什么。下文主语是动作对象，故用被动语态，结合语境可知选B。