真正的护城河是用户对你的依赖。
The real moat is users' dependence on you.
数学是一种超越文化和语言障碍的通用语言。
The only time I'm nervous is when I have to be myself.
Concerning the gods, I cannot know either that they exist or that they do not exist, nor what form they might have, for there is much to prevent one's knowing: the obscurity of the subject and the shortness of man's life.
The heart that loves, lives.