It is pretty well understood controls the flow of carbon dioxide in and out the atmospher

发布时间：2020-08-17 08:35:08

It is pretty well understood      controls the flow of carbon dioxide in and out the atmosphere today.
A. that
B. when
C. what
D. how

网友回答

A. that
B. when
(答案→)C. what
D. how
解析：分析句子结构可知：句子属于形式主语格式；另外主句中缺少主语。双重作用的引导词只能是what。
以上问题属网友观点，不代表本站立场，仅供参考！