【题目】 worries the public that air pollution is becoming more and more serious these days.
A. It B. That C. What D. This
在线课程【答案】A
【解析】考查it的用法。句意：这些天空气污染正变得越来越严重，这让公众担忧。本句用it作形式主语，真正的主语是that air pollution is becoming more and more serious these days，故选A。