小树与阿林都能做面包和围巾。分工与交换，怎样改变两人的收获？Mia and Lin can both make bread and scarves. How can specialization and exchange change what they can have?
第 1 步：每个选择都有放弃Step 1: Every choice gives something up
先把时间限制写清楚。Make the time limit explicit.
同一小时不能重复使用。做更多面包，会少做一些围巾。放弃的最好选择叫机会成本。它不一定用钱表示。The same hour cannot be used twice. Making more bread leaves less time for scarves. The best forgone alternative is opportunity cost. It need not be measured in money.
第 2 步：比较相对代价Step 2: Compare relative costs
谁更快，还不足以决定什么？Why is being faster not the whole story?
小树每小时做四个面包或一条围巾。阿林做两个面包或两条围巾。小树做面包的相对代价较低。阿林做围巾的相对代价较低。Mia can make four loaves or one scarf per hour. Lin can make two loaves or two scarves. Mia has a lower relative cost for bread; Lin has a lower relative cost for scarves.
第 3 步：交换有范围，也有成本Step 3: Trade has a range and costs
分工以后，怎样判断双方受益？After specialization, when can both gain?
交换比例要比较双方机会成本。运输和交易也会消耗资源。总收益增加不保证人人都受益。分配与调整成本需要另外讨论。Compare the exchange rate with both opportunity costs. Transport and transactions use resources. A rise in total gains does not ensure every person gains. Distribution and adjustment costs need separate attention.
🎮 机制实验室：观察，再判断🎮 Mechanism lab: observe, then decide
两人各有一小时。小树每小时四面包或一围巾；阿林二面包或二围巾。比较分工前后。Each has one hour. Mia makes 4 loaves or 1 scarf; Lin 2 loaves or 2 scarves. Compare different time allocations.
一句话记住它：Remember it:贸易收益来自相对代价差异，也受运输和分配影响。Trade gains arise from relative costs and are shaped by transport and distribution.
同一小时不能重复使用。The same hour cannot be used twice.小树每小时做四个面包或一条围巾。Mia can make four loaves or one scarf per hour.交换比例要比较双方机会成本。Compare the exchange rate with both opportunity costs.
比较优势模型：较高把握。例子假定产出可分、技术固定，不能直接预测具体贸易政策。High confidence in comparative-advantage logic. The example assumes divisible output and fixed technology; it does not predict a particular trade policy.
核对日期：2026 年 10 月 6 日。文字与配图由 AI 生成；已做来源核对及程序测试，待人工复核。Checked 6 October 2026. Text and illustrations are AI-generated. Sources and software checks were performed; human review is pending.
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