I'm not upset that you lied to me, I'm upset that from now on I can't believe you.

心灵是一个相互关联过程的动态系统。

In international trade, a country should specialize in the production of goods for which it has a comparative advantage, and trade with other nations to maximize overall economic welfare.

What you actually pay for something is at least twice the listed price because of the energy， time， money needed to set it up， learn， maintain， repair， and dispose of at the end. Not all prices appear on labels. Actual costs are 2x listed prices.

To do mathematics is to engage in an act of discovery and conjecture, intuition and inspiration.