（What) is known to us all is that China is a developing country (belonging to) the Third World.

题目

（What) is known to us all is that China is a developing country (belonging to) the Third World.
A:As;belong toB:It;belongs toC:What;belonging toD:That;belonging to为什么选C?

答案

因为
（What) is known to us all 是主语从句中的主语
(belonging to) the Third World 是 developing country 的后置定语