Charles did what he could the servant although he himself was in danger.A. rescueB. resc

问题补充：

Charles did what he could the servant, although he himself was in danger.

A. rescue

B. rescued

C. to rescue

D. rescuing

答案：

A. rescue

B. rescued

(答案→)C. to rescue

D. rescuing

解析：此题中could后省略了do,而不定式to rescue是目的状语。