—— 请按键盘 空白键 开始游戏 ——

That's the only trouble with being a dog...they never tell you anything…
The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge.
Mathematics is not a deductive science—that's a cliché. When you try to prove a theorem, you don't just list the hypotheses and then start to reason. What you do is trial and error, experimentation, guesswork.
证明是一种让自己和他人相信某事为真的方式。