一个人肚子空空,心事重重,总是睡不好觉的。
The concept of truth is inseparable from the concept of freedom.
数学的力量来自于它的抽象和概括能力,将具体问题转化为普遍真理。
The essence of creativity is figuring out how to use what you already know in order to go beyond what you already think.