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.
你必须准备好受苦并享受这种痛苦。
A nation's strength grows from the fertility of its fields and the wisdom of its farmers.
The true genius shudders at incompleteness — and usually prefers silence to saying something which is not everything it ought to be.
The beauty of music lies in its ability to evoke emotions without saying a word.
梦是愿望和恐惧相遇的地方。当愿望和恐惧完全平衡时，你称这个梦为噩梦。
我们都是自己的幽灵，徘徊在我们曾经生活过的地方。