出处：按学科分类—语言、文字 中国对外翻译出版公司《汉英成语词典》第17页（233字）
受过创伤之后，回想所受痛苦，有警惕未来之意，例今天我们应当痛定思痛，深刻领会过去的内忧外患是怎样造成的。
We should draw a lesson from the bitter past and figure out how and why we were beset by foreign aggression and domestic troubles．