throw (yourself) on/upon (someone's) mercy
to ask someone to help you or to forgive you when you are in a difficult situation.
If all else fails, I might throw myself on Sandra's mercy and see if she'll drive me there.
英语词组固定搭配大全包含18674条英汉双解词组，基本涵盖了全部常用英文词组、短语的翻译及用法，是英语学习的有利工具。