求翻译：二是天下没有亏本的买卖。因为经济学原理的最基本假设是人都是理性的个体，具体的解释就是追求利益最大化，至少是不能亏本，如果亏本就还不如不做。是什么意思？

Second, there is no trading loss. Principles of economics, the basic assumption is that people are rational individuals, the interpretation is to seek maximum benefits, at least not lose money if a loss is not as good as not to.

There is no 2 is a losing trade. Because economics is the most basic assumption that people are rational individual, and the explanation is that quest for the maximum benefit, at least, not losing money, losing money if it is better to do.

Two is business which the world has not lost money.Because the principle of economics most basic supposition is the human all is the rational individual, the concrete explanation pursues the benefit maximization, cannot lose money at least, if loses money on the might as well does not do.

Second, there's no loss on the sale. Because people are the most basic assumptions of economic principles are rational individual, specific explanation is that seek to maximize the benefits, at least not lose money, if it might as well not to do at a loss.

正在翻译，请等待...