＿is known to us all is that the 2012 Olympic Games will take place in London.

题目

＿is known to us all is that the 2012 Olympic Games will take place in London.
答案是用what.我想问的是,为什么不能用it呢?

答案

因为有is在这句句子里,所以（what is known to us all）就是主语.is是谓语,that后面是宾语.在这里what填补句子缺失的成分如果没有all后面的is,那么就用itWhat is known to us all is that the 2012 Olympic Games wi...