is known to us all is that the olympic Games will take place in Beijing.A It B What C

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：

解析：通过分析句子结构，可知这是一个复合句，其中包含一个主语从句，且引导词在从句中作主语，故用What。