Unlike most costs discussed in economics, an opportunity cost doesn't necessarily involve money.

 The opportunity cost of any action is simply the next best alternative to that action: What you would have done if you didn't make the choice that you made?与经济学中讨论的大多数成本不同，机会成本并不一定涉及金钱。任何行动的机会成本都只是该行动的次优方案：如果你没有做出这个选择，你会怎么做？“

机会成本是什么?

The notion of opportunity cost is critical to the idea that the true cost of anything is the sum of all the things that you have to give up.
所谓机会成本，其实说的是你必须为之放弃的一切以及所要付出的代价。
Opportunity cost considers only the next best alternative to an action, not the entire set of alternatives, and takes into account all of the differences between the two choices.
机会成本只考虑行动的下一个最佳选择，而不是全部备选方案，并且要考虑到两个选择之间的所有差异。

We actually deal with the concept of opportunity cost every day. 

For example, options for a day off work might include going to the movies, staying at home to watch a baseball game, going out to coffee with friends.

Choosing to go to the movies means the opportunity cost of that action is the second choice.

事实上，我们每天都在与机会成本的概念打交道。例如，休息一天的选择可能包括去看电影，待在家里看棒球比赛，或者和朋友出去喝咖啡。选择去看电影意味着这个行动的机会成本是第二选择。

显性和隐性机会成本

Explicit Versus Implicit Opportunity Costs.

Generally, making choices includes two types of cost: explicit and implicit. Explicit costs are monetary expenses, while implicit costs are intangible and therefore hard to account for.
一般来说，成本有两种类型：显性和隐性。显性成本是货币支出，但是隐性成本是无形的，因此很难解释。
In some cases, such as weekend plans, the notion of opportunity cost includes only these forgone alternatives, or implicit costs.
在某些情况下，比如周末计划，机会成本的概念只包括这些被放弃了的选择，或者隐性成本。
But in others, such as a business's profit maximization, opportunity cost refers to the difference in the total of this type of implicit cost and the more typical explicit monetary cost between the first choice and the next best alternative.
但在其他方面，例如企业的利润最大化，机会成本指的是这种隐性成本的总和与最优和次优选择之间更典型的显性货币成本的差异。