I think it’s important healthy.A. keepB. keepingC. keepsD. to keep

问题补充：

I think it’s important healthy.

A. keep

B. keeping

C. keeps

D. to keep

答案：

A. keep

B. keeping

C. keeps

(答案→)D. to keep

解析：整个句子是宾语从句。分析从句，it是代词，是句子的形式主语，真正的主语是不定式to keep healthy，选D.