—What should I do doctor? —healthy you should take more exercise.A. To keepB. KeepC. Kee

问题补充：

—What should I do, doctor? —healthy, you should take more exercise.

A. To keep

B. Keep

C. Keeping

D. Kept

答案：

(答案→)A. To keep

B. Keep

C. Keeping

D. Kept

解析：考查动词不定式用法。句意：医生，我该怎么做。——为了保持健康，你应该多锻炼。不定式做宾语，表示具体的将要进行的动作。故选A。