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.
We must focus on customers and continuously improve the quality of products and services.
The best art is about change—about the movement of thought and the transformation of perception.
植物油作为发动机燃料的使用在今天看来可能微不足道，但这些油或许会随着时间的推移变得像石油和煤焦油产品一样重要。
Writing is a way of exorcising demons and a process of self-discovery.