When you arrive at your room in a hotel， locate the emergency exits. It only takes a minute.

The only way to deal with an unfree world is to become so absolutely free that your very existence is an act of rebellion.

你必须足够坚强才能独自站立，足够聪明才能知道何时需要帮助，足够勇敢才能寻求帮助。

数学研究是具体与抽象之间不断的对话。