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.

The less you respond to negative people, the more peaceful your life becomes.

未来不是礼物。它是一种成就。

解释：情绪变化会影响身体生理反应，如贪心时口水增多，悲哀时流泪，体现了情绪与健康的关联。