外交的目标是建立稳定的国际关系，以促进全球和平、繁荣和可持续发展。

The old-fashioned dictator does not exist under scientific management. The man at the head of the business under scientific management is governed by rules and laws which have been developed through hundreds of experiments just as much as the workman is.

PAC学习框架提供了一种形式化的方法来量化概念类的可学习性。