中心地的等级越高，其数量越少。

Efficiency in extraction isn't just good for profits; it's good for the planet.

The rule of law is a political ideal, not a legal one.

Successful gaming companies should not only make money but also have a positive impact on society.

科学的历史是新知识生产的历史。

过去是一个陌生的国度；他们做事的方式不同。