中心地的等级越高，其数量越少，影响范围越大。

I'm fascinated by medicine because it's the line between life and death.

The only way to discover the limits of the possible is to go beyond them into the impossible.

仅仅知道如何使用工具是不够的；还必须了解它们何时适用。

我们越了解自己的偏见，就越能利用它们为自己服务。