问题补充：
is known to us all is that the Olympic Games will take place in Beijing.
A. It
B. What
C. As
D. Which
答案：
A. It
B. What
C. As
D. Which
解析：解析分析题干结构“is known to us all”是主语从句，从句中缺少主语，what引导主语从句，在从句中作主语。如果选it，需去掉all后的is;如果选as;需去掉is that。
【标签】(08福建27)
