The past is never dead. It's not even past.
每场比赛都是证明自己的新机会。
What fun was it without having me around?
Every story is a chance to see the world differently.
里氏替换原则是面向对象编程中的一个基本概念,它指出子类的对象应该能够替换超类的对象而不影响程序的正确性。