bitter lesson是什么意思

双语例句

(1)The mining disaster not only teaches us a bitter lesson, but also reveals the blind area of law.

矿难，不仅使我们受到了一次次的惨痛教训，同时也突显了一些法律的盲区。

(2)No comrade in the Party must ever forget this bitter lesson and we must all take warning from it.

这个惨痛的历史教训，我们全党同志一定要永远记取，引以为鉴。