He did what he couldher out of trouble.A. helpB. tohelpC. helpedD. helping

问题补充：

He did what he couldher out of trouble.

A. help

B. tohelp

C. helped

D. helping

答案：

A. help

(答案→)B. tohelp

C. helped

D. helping

解析：句意：他尽他所能帮助他摆脱困难。What he could是宾语从句，后面省略了to，所以需要填的是目的状语，只有不定式可以做目的状语，选B。