is known to us all is that America is a developed country the First World.
A. Which; belonging to
B. as; belonging to
C. what; belonging to
D. It; belonging to
网友回答
A. Which; belonging to
B. as; belonging to
(答案→)C. what; belonging to
D. It; belonging to
解析：我们都知道美国是属于第一世界的发达国家。第一空是主语从句；第二空是现在分词短语作定语。