As we all know China is a developing country to the third world.A. belongsB. belongC. be

问题补充：

As we all know, China is a developing country to the third world.

A. belongs

B. belong

C. belonging

D. belonged

答案：

A. belongs

B. belong

(答案→)C. belonging

D. belonged

解析：考查非谓语动词。句子的谓语是is，不能再用动词原形，排除A、B；country与belong之间是主谓关系，应该用现在分词，作后置定语，相当于which belongs to...。故选C。