里氏替换原则是面向对象编程中的一个基本概念，确保派生类可以替代其基类使用，而不会改变程序的正确性。
The Liskov Substitution Principle is a fundamental concept in object-oriented programming, ensuring that derived classes can be used in place of their base classes without altering the correctness of the program.
我喜欢对一堵墙说话，世界上只有它不会反驳我。
The most profound ideas in mathematics often arise from the simplest observations.