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。
The Liskov Substitution Principle is a fundamental concept in object-oriented programming, stating that objects of a superclass should be replaceable with objects of a subclass without affecting the correctness of the program.
阅读不应该被当作一项家务或责任呈现给孩子。它应该被当作一份珍贵的礼物送给他们。
You see things; and you say, 'Why?' But I dream things that never were; and I say, 'Why not?'
我对记忆了解得越多，就越不信任它。
We've been through a lot together, and that's what makes us stronger.
In the end, all we have are words.
追求知识是一场没有终点的旅程。