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。

不要等待机会，去创造机会。

我不在乎过去，我在乎未来。

When someone tells you about the peak year of human history， the period of time when things were good before things went downhill， it will always be the years of when they were 10 years sold — which is the peak of any human’s existence.

出自《论语·子罕》。年轻人是值得敬畏的啊，你怎么知道他之后不如当今的你呢？