Principles of Economics
1．Economy
The word economy comes from a Greek word for “one who manages a household.”
经济一词来源于希腊语，意思是“管理家庭的人”。
2.Scarcity 稀缺
Means that society has limited resources and therefore cannot produce all the goods and services people wish to have.
…意思是说，社会拥有有限的资源，不能生产出人们想要的所有物品与劳务。
3.Economics 经济学
Economics is the study of how society manages its scarce resources.
经济学——研究社会如何管理稀缺资源的学科。
4.How People Make Decisions
4.1People face tradeoffs.人们面临权衡取舍
To get one thing, we usually have to give up another thing.
为了得到我们喜爱的一件东西，我们通常不得不放弃另一件喜爱的东西。Efficiency v. Equity
Efficiency means society gets the most that it can from its scarce resources. Equity means the benefits of those resources are distributed fairly among the members of society.
效率——社会能从其稀缺资源中得到最多东西的特性。
平等——社会资源的经济成果在社会成员中公平分配的特性
4.2The cost of something is what you give up to get it.
某东西的成本就是为得到它所放弃的东西
Decisions require comparing costs and benefits of alternatives.
做出决策时需要比较可供选择的行动方案的成本与收益
The opportunity cost of an item is what you give up to obtain that item.
机会成本——为了得到某种东西所必需放弃的东西。
4.3Rational people think at the margin.理性人考虑边际量
Marginal changes are small, incremental adjustments to an existing plan of action.
边际变动——对当前行动计划微小的增量调整
Marginal changes in costs or benefits motivate people to respond.
The decision to choose one alternative over another occurs when that alternative’s marginal benefits exceed its marginal costs!
成本或收益的边际改变会激励人们做出反应。
当一个方案的边际收益大于边际成本时，人们选择这个方案，而不去选择别的。
4.4People respond to incentives.人们会对激励做出反应
5.How People Interact with each other
5.1Trade can make everyone better off.贸易可以使每个人状况更好。
People gain from their ability to trade with one another.
Competition results in gains from trading.
Trade allows people to specialize in what they do best.
人们可以从与他人相互交易的能力中获益。
竞争可以使人们从贸易中获益。
贸易可以让人们从事他们最专长的工作。
5.2Markets are usually a good way to organize economic activity.
市场通常是组织经济活动的一种好方法。
A market economy is an economy that allocates resources through the decentralized decisions of many firms and households as they interact in markets for goods and services.
Households decide what to buy and who to work for.
Firms decide who to hire and what to produce.
市场经济——当许多企业和家庭在物品与劳务市场上相互交易时通过他们的分散决策配置资源的经济。
家庭决定购买什么和为谁工作。
企业决定雇佣谁和生产什么。
Adam Smith made the observation that households and firms interacting in
