The doctor did what he could the kid.A. saveB. to saveC. savedD. saving

问题补充：

The doctor did what he could the kid.

A. save

B. to save

C. saved

D. saving

答案：

A. save

(答案→)B. to save

C. saved

D. saving

解析：这位医生尽其所能的来救这个孩子。不定式做宾语补足语表示具体的将要进行的动作，结合语境，可知选B。