问题补充:
—Have your read the article A Dirty Beijing, which is about air pollution?
—Yes. It’s highly informative. I no idea that the PM2.5 there sometimes reached 300.
A. have
B. had
C. will have
D. would have
答案:
A. have
(答案→)B. had
C. will have
D. would have
解析:考查情景交际和时态。句意:--你看过A Dirty Beijing那篇文章了吗?它是关于空气污染的。--是的。真是增长见识啊。我(以前竟然)不知道北京的PM2.5有时能达到300。根据对话情景可知,在看A Dirty Beijing之前,“我”不知道PM2.5达到300这件事,看A Dirty Beijing是过去的动作,故用一般过去时。故选B。