quid pro quo
/ˌkwɪdprəʊˈkwəʊ/noun
(pl. -os)
- a favour or advantage granted in return for something报酬; 回报：
the pardon was a quid pro quo for their help in releasing hostages.
宽恕是对他们帮着释放人质的报答。
词源
mid 16th cent. (denoting a medicine substituted for another)： Latin， 'something for something'.