—— 请按键盘 空白键 开始游戏 ——

Mathematics is not a spectator sport. You have to get involved.
Psychology is a science, and teaching is an art; and sciences never generate arts directly out of themselves.
If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.
不能容人,就没有可以亲近的人。