I turned to the headmaster and he promised to do everything _ his power to help. me out.
A. beyond
B. above
C. under
D. within
网友回答
A. beyond
B. above
C. under
(答案→)D. within
解析：考查介词，beyond 超出范围，above 在什么上面，under 在什么下面，within 在什么范围之内，句意：我向校长去求助他答应在他的权利范围之内，他会尽力帮助我。所以选D。