经济景观是一个由不同等级的中心地组成的系统，每个中心地为特定区域服务。

The only person you should try to be better than is the person you were yesterday.

数学的研究就像空气或重力——它无处不在，即使你看不到它。

The poet is a man who can make the impossible possible.

数学之美在于它能够将复杂的事物简化。