很高兴为你解答.

保证正确率~!



有好几种改法呢,分别如下：
1、It is known to all that Taiwan belongs to China. 
（ It 作形式主语,that 引导真正主语）
2、As is know to all , Taiwan belongs to China. 
（ As 引导的非限制性定语从句）
3、What is known to all is that Taiwan belongs to China. 
（ What 引导的主语从句）
4、That Taiwan belongs to China is known to us all.
( That 引导的主语从句）
    众所周知,台湾属于中国.


祝开心~!