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

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。