Economics is the study of how societies use scarce resources to produce valuable goods and services and distribute them among different individuals. If we think about the definitions, we find two key ideas that run through all of economics:

数学的艺术在于发现包含所有普遍性萌芽的特殊案例。

We must strengthen international energy cooperation with an open and collaborative attitude to achieve mutual benefits.

所有人类行为都有以下七个原因中的一个或多个：机会、自然、强迫、习惯、理性、激情和欲望。

我不是说唱歌手，我是一个阿拉伯语的传奇。