Water can absorb and give off a lot of heat without big changes in temperature, thus creating a ______environment.
A. stable B. sensitive
C. common D. peaceful
A modern city has been set up in _________ was a wasteland ten years ago.
A. what B. which C. that D. where
Don’t be ________ by products claiming to help you lose weight in a couple of weeks.
A. taken off B. taken in
C. taken away D. taken out
Meeting my uncle after all these years was an unforgettable moment, ________ I will always treasure.
A. that B. one C. it D. what
It is pretty well understood_______ controls the flow of carbon dioxide in and out the atmosphere today.
A. what B. when C. that D. how
假设你是李华，David是你的美国网友。他对目前中国出现的雾霾天气很关注，来信向你询问此事。请你给他写封回信。 主要内容如下：
1.感谢他的关注。
2.简介雾霾 （smog） 天气给人们的身体、生活带来的危害。
3.谈谈你的感想。
注意：可适当增加细节，以使行文连贯流畅；开头与结尾已写好，不计人总词数；词数：100左右
