请教一个问题（比较结构）

   (A) to warm the Earth's atmosphere even more rapidly than carbon dioxide during the next fifty years

   (B) to warm the Earth's atmosphere even more rapidly over the next fifty years than carbon dioxide will

   (C) during the next fifty years to warm the Earth's atmosphere even more rapidly than carbon dioxide

   (D) a warming of the Earth's atmosphere during the next fifty years even more rapid than carbon dioxide's

   (E) a warming of the Earth's atmosphere even more rapid than carbon dioxide's will be over the next fifty years

答案是B

不是很明白，虽然next fifty years表示将来，但是threaten是一般现在时，为什么than后面一定要加will表示一般将来时啊？

关注！

说下个人理解：

threaten to warm陈述现在的事实

但是比较的部分是比较将来的情况even more rapidly over the next fifty year than xx will