问题补充:
is known to us all is that America is a developed country the First World.
A. Which; belonged
B. As; belonging to
C. What; belonging to
D. It; belonging
答案:
A. Which; belonged
B. As; belonging to
(答案→)C. What; belonging to
D. It; belonging
解析:第一空考查what引导的主语从句,在主语从句中,what做主语,第二空考查belong to做定语,belong to不能用被动,用现在分词做定语,句意是:众所周知的是美国是属于第一世界的发达国家。选C。