on rescuing her sick son the poor mother has been working 16 hours a day.A. To bendB. B

问题补充：

on rescuing her sick son, the poor mother has been working 16 hours a day.

A. To bend

B. Being bent

C. Having bent

D. Bent

答案：

A. To bend

B. Being bent

C. Having bent

(答案→)D. Bent

解析：句意：这位可怜的母亲决意要治好她生病的儿子，现在已经工作16个小时了。Bent在这里是形容词： 执意要的；有强烈意向的；决心的，决意的，与on，upon搭配。故选D。

考点: 考查非谓语动词的用法。