As is known to all USA is biggest developed country in the world.A. the; 不填B. 不填; theC.

问题补充：

As is known to all, USA is biggest developed country in the world.

A. the; 不填

B. 不填; the

C. the; the

D. 不填; 不填

答案：

A. the; 不填

B. 不填; the

(答案→)C. the; the

D. 不填; 不填

解析：考查冠词。the USA指美国，形容词最高级前面使用定冠词the;句意：众所周知，美国是世界上最大的发达国家。