每一个挑战都是伪装的机遇。
Every challenge is an opportunity in disguise.
The concept of probably approximately correct (PAC) learning has been foundational in computational learning theory.
去做高尚的事情，不要整天只是做梦。
The meaning of a word is not a mental entity， but a social practice.
我们都是一样的，但我们又都不同。