quid pro quo
交换条件
quid pro quo是个拉丁文词组，直译成英文是what for what，也就是「以一物易一物」，通常指双方说好的交换条 件。电影《沉默的羔羊》中，有一段情节是探员听从囚犯的 要求做了一个动作后，就大声提醒囚犯：Quid pro quo， Doctor! Quid pro quo.，囚犯于是也依约向探员透露一些消白。
In most European armies in the first half of the 17th century，rapes by unpaid soldiers occurred in large numbers in front of officers and were not stopped because they were part of the quid pro quo of what you got for being a soldier.(出自：TIME，Feb. 22，1993， p. 48)
在十七世纪前半，大多数欧洲国家的军队都发生大批不支薪士兵 公然在长官面前强暴妇女、却未遭到制止的事件，因为强暴的权 利是当兵的交换条件之一。