carbon dioxide is said ________ the earth twice as quickly as previously feared.
问题描述：
carbon dioxide is said ________ the earth twice as quickly as previously feared.
A.to be heating C.to have heated
可是答案给的是A 现在二氧化碳不还是在加热地球吗？
答
A.表示二氧化碳现在正在以之前所担心的速度的两倍使地球变暖.