_is known to us all is that the Chinese goverment has spared

答案是D,what引导主语从句 并作主语从句的中的主语.
选项AC,that引导 名词性从句时 不能作句子成分 故错
选项B,it.是形式主语 须把第二个is去掉
如果用 as 则是 非限制性定语从句 须把 is that去掉 换成逗号
_what is known to us all is that the Chinese goverment has spared no efforts to protect people from fake food
=it is known to us all that the Chinese goverment has spared no efforts to protect people from fake food
=as is known to us all ,the Chinese goverment has spared no efforts to protect people from fake food

What