📚 Year 12 Cambridge Economics: Rapid Memorisation Guide to Key Terms | Year 12 剑桥经济：关键术语速记指南
Mastering the precise vocabulary of economics is the key to unlocking high marks in Cambridge AS-Level exams. This guide breaks down essential Year 12 terms into memory-friendly clusters, pairing clear definitions with real-world cues so you can recall them quickly under pressure.
掌握经济学精准的词汇是剑桥 AS 考试拿高分的关键。这份指南将 Year 12 的核心术语分成易于记忆的集群，把清晰的定义与真实世界的线索配对，让你在考试压力下也能快速回忆。
1. Scarcity, Opportunity Cost and PPF | 稀缺、机会成本与生产可能性边界
Scarcity: The fundamental economic problem where limited resources are insufficient to satisfy unlimited human wants. Memory aid: “Limited pie, too many dinner guests.”
稀缺：指有限资源不足以满足无限人类欲望的基本经济问题。记忆线索：”有限的大饼，太多的用餐者。”
Opportunity Cost: The value of the next best alternative sacrificed when a choice is made. Every ‘yes’ to one option is a ‘no’ to another, so always ask: “What did I give up?”
机会成本：做出选择时所放弃的次优选项的价值。对某个选项说 “好” 就是对另一个说 “不”，所以永远问：”我放弃了什么?”
Production Possibility Frontier (PPF): A curve showing the maximum attainable combinations of two outputs when all resources are fully and efficiently used. Points inside the curve mean underemployment; points outside are unattainable without growth or trade. Picture a student dividing a fixed study time between Economics and Maths.
生产可能性边界 (PPF)：一条曲线，显示所有资源被充分高效利用时，两种产出的最大可达组合。曲线内的点代表资源未充分利用；曲线外的点除非有增长或贸易否则无法达到。想象一个学生把固定的学习时间分配给经济和数学。
2. Demand and Supply | 需求与供给
Demand: The quantity of a good that consumers are willing and able to buy at each price over a period, ceteris paribus. The Law of Demand states that as price falls, quantity demanded rises. Think of a clearance sale: lower price, more shoppers buy.
需求：在其他条件不变的情况下，一段时间内消费者在不同价格上愿意并能够购买的商品数量。需求定律指出价格下降时需求量上升。想想清仓甩卖：价格低，更多顾客购买。
Supply: The quantity producers are willing to sell at each price, influenced mainly by profit incentive. The Law of Supply says price rises, quantity supplied rises. A coffee shop extends opening hours when latte prices go up.
供给：生产者在每个价格上愿意出售的数量，主要受利润动机驱动。供给定律说价格上升，供给量上升。拿铁咖啡涨价时咖啡店会延长营业时间。
Equilibrium: The price where quantity demanded equals quantity supplied, balancing the plans of buyers and sellers. In a tug-of-war, equilibrium is when both sides stop moving. Disequilibrium creates shortages (excess demand) or surpluses (excess supply).
均衡：需求量等于供给量时的价格，平衡买方与卖方的计划。在拔河比赛中，均衡就是双方都停止移动的时刻。非均衡产生短缺（超额需求）或过剩（超额供给）。
3. Elasticities | 弹性
Price Elasticity of Demand (PED): Measures responsiveness of quantity demanded to a change in price.
PED = %Δ Quantity Demanded ÷ %Δ Price
If PED > 1, demand is price-elastic (luxuries, substitutes available). If PED < 1, demand is price-inelastic (necessities, addictive goods). A cinema ticket price hike cuts sales sharply = elastic.
需求价格弹性 (PED)：衡量需求量对价格变化的反应程度。如果 PED > 1，需求富有弹性（奢侈品、有替代品）；如果 PED < 1，需求缺乏弹性（必需品、成瘾品）。电影院票价上涨导致销量锐减 = 富有弹性。
Price Elasticity of Supply (PES): Responsiveness of quantity supplied to price changes. Formula: %Δ Quantity Supplied ÷ %Δ Price. Spare capacity and time to produce boost PES. A bakery can quickly bake more bread when price rises, so PES is high for bread.
供给价格弹性 (PES)：供给量对价格变化的反应程度。公式：%Δ 供给量 ÷ %Δ 价格。闲置产能和生产时间会提高 PES。面包房在涨价时可以快速烤更多面包，所以面包的 PES 很高。
Income Elasticity of Demand (YED): %Δ quantity demanded ÷ %Δ income. Positive for normal goods, negative for inferior goods (e.g. bus travel falls as incomes rise). Luxury vacations have YED > 1.
需求收入弹性 (YED)：%Δ 需求量 ÷ %Δ 收入。正常品为正值，低档品为负值（如收入上升，公交出行下降）。豪华度假的 YED > 1。
4. Market Efficiency and Surplus | 市场效率与剩余
Consumer Surplus: The extra satisfaction gained by consumers paying less than the maximum they were willing to pay. It is the area below the demand curve and above the market price. If you were ready to pay £10 for a book but bought it for £6, your consumer surplus is £4.
消费者剩余：消费者支付低于他们最高意愿支付价格所获得的额外满足。它是需求曲线下方、市场价格上方的面积。你若准备花 10 英镑买一本书却以 6 英镑买到，消费者剩余就是 4 英镑。
Producer Surplus: The benefit producers receive by selling at a market price above their minimum acceptable price. Area above the supply curve and below the market price.
生产者剩余：生产者在市场价格高于他们最低可接受价格出售时获得的利益。供给曲线上方、市场价格下方的面积。
Allocative Efficiency: Achieved when price equals marginal cost (P=MC), where resources are distributed to produce what society values most. Any deviation creates a deadweight loss. Imagine a fruit stall that produces exactly the mix of apples and oranges customers want — no waste.
配置效率：当价格等于边际成本 (P=MC) 时达到，此时资源被分配去生产社会最看重的商品。任何偏离都会产生无谓损失。想象一个水果摊正好产出顾客所需要的苹果和橙子组合——没有浪费。
5. Market Failure: Externalities | 市场失灵：外部性
Negative Externality: A cost imposed on a third party not involved in the transaction. Example: factory smoke harming residents’ health. Social cost = private cost + external cost. Market overproduces because firms ignore external costs.
负外部性：强加给未参与交易第三方的成本。例如：工厂烟雾损害居民健康。社会成本 = 私人成本 + 外部成本。企业忽视外部成本导致市场过度生产。
Positive Externality: A benefit gained by a third party. Vaccination protects others by herd immunity. Social benefit = private benefit + external benefit. Markets underproduce without subsidy.
正外部性：第三方获得的好处。疫苗接种通过群体免疫保护他人。社会收益 = 私人收益 + 外部收益。没有补贴时市场生产不足。
Social Optimum: The output level where social marginal cost equals social marginal benefit (MSC = MSB). This is the allocatively efficient point that accounts for all externalities.
社会最优：社会边际成本等于社会边际收益时的产出水平 (MSC = MSB)。这是考虑了所有外部性后达到配置效率的点。
6. Market Failure: Public Goods and Information | 市场失灵：公共物品与信息
Public Good: A good that is non-rival (one person’s use does not reduce availability for others) and non-excludable (impossible to stop non-payers from consuming). National defence and street lighting are classic examples. Free-rider problem leads to under-provision by private markets.
公共物品：具有非竞争性（一人使用不减少他人可用量）和非排他性（无法阻止未付费者消费）的商品。国防和路灯是典型例子。搭便车问题导致私人市场供给不足。
Quasi-public Good: A good exhibiting some but not all public good features, e.g., toll roads (excludable but largely non-rival until congested).
准公共物品：表现出部分但非全部公共物品特征的商品，如收费公路（可排他，但拥挤前基本非竞争）。
Information Asymmetry: A situation where one party has more or better information, causing market failure. Adverse selection occurs before a deal (used car seller knows faults), and moral hazard occurs after (insured person takes more risks).
信息不对称：一方拥有更多或更优信息导致市场失灵的情形。逆向选择发生在交易前（二手车卖家知道故障），道德风险发生在交易后（投保人更冒险）。
7. Government Microeconomic Intervention | 政府微观干预
Indirect Tax: A charge levied on goods and services, shifting the supply curve leftwards. A specific tax is a fixed amount per unit; an ad valorem tax is a percentage of price. Cigarette taxes internalise negative externalities.
间接税：对商品和服务征收的费用，使供给曲线左移。从量税是每单位固定金额；从价税是价格的一定百分比。香烟税收把负外部性内部化。
Subsidy: A payment from government to producers, lowering costs and shifting supply rightwards, increasing quantity and lowering price. Electric vehicle subsidies encourage uptake of positive externality goods.
补贴：政府向生产者支付的款项，降低其成本并使供给曲线右移，增加产量并降低价格。电动车补贴鼓励正外部性商品的采用。
Maximum Price (Ceiling): A price set below equilibrium to protect consumers, e.g. rent controls. It creates a shortage unless accompanied by rationing or public housing.
最高限价：设定在均衡价以下以保护消费者的价格，如租金管制。它会带来短缺，除非配给或提供公屋。
Minimum Price (Floor): A price above equilibrium to support producers, e.g. minimum wage or agricultural price supports. Leads to excess supply, requiring government stockpiling or disposal.
最低限价：高于均衡价以支持生产者的价格，如最低工资或农产品价格支持。导致超额供给，需政府收储或处置。
8. Macroeconomic Objectives and Indicators | 宏观经济目标与指标
Economic Growth: An increase in a country’s real Gross Domestic Product (GDP) over time, indicating more goods and services produced. It should ideally be sustainable to raise living standards.
经济增长：一国实际国内生产总值 (GDP) 随时间增加，表明生产的商品与服务增多。理想上应是可持续的以提高生活水准。
Inflation: A sustained rise in the general price level, measured by the Consumer Price Index (CPI). A low, stable rate (often 2% target) preserves purchasing power; hyperinflation damages confidence.
通胀：一般物价水平持续上升，用消费者价格指数 (CPI) 衡量。低而稳定（通常目标 2%）维护购买力；恶性通胀摧毁信心。
Unemployment: The percentage of the labour force actively seeking work but unable to find it. Measured by the Labour Force Survey. High unemployment wastes human capital and raises social costs.
失业：劳动力中积极寻找工作但找不到的比例，由劳动力调查测算。高失业浪费人力资本并增加社会成本。
Balance of Payments Current Account: A record of flows of goods, services, investment income and transfers. A deficit means more money leaves than enters; persistent deficits may signal competitiveness problems.
国际收支经常账户：记录货物、服务、投资收入和转移的流动。逆差意味着流出的资金多于流入；持续逆差可能预示竞争力问题。
9. Aggregate Demand and Aggregate Supply | 总需求与总供给
Aggregate Demand (AD): Total spending on domestic goods and services at each price level.
AD = Consumption + Investment + Government spending + (Exports – Imports)
A fall in interest rates boosts consumption and investment, shifting AD rightwards. Think of AD as the entire nation’s shopping list.
总需求 (AD)：在每一物价水平上对国内商品与服务的总支出。AD = 消费 + 投资 + 政府支出 + (出口 – 进口)。利率下降刺激消费和投资，使 AD 曲线右移。把 AD 想象成整个国家的购物清单。
Short-run Aggregate Supply (SRAS): The total output firms are willing to supply at each price level, assuming resource prices (wages) remain sticky. Rises in energy costs shift SRAS left, causing cost-push inflation.
短期总供给 (SRAS)：假设资源价格（工资）黏性时，企业在每一物价水平愿意供给的总产出。能源成本上升使 SRAS 左移，引起成本推动型通胀。
Long-run Aggregate Supply (LRAS): The potential output of an economy at full employment, independent of the price level. Growth in the quantity or quality of factors (labour, capital, technology) shifts LRAS rightwards.
长期总供给 (LRAS)：经济在充分就业时的潜在产出，独立于价格水平。要素数量或质量（劳动力、资本、技术）的增长使 LRAS 向右移。
10. Macroeconomic Policies | 宏观经济政策
Fiscal Policy: Use of government spending and taxation to influence the economy. Expansionary fiscal policy (higher spending, lower taxes) boosts AD; contractionary policy cools down an overheating economy. A government building a new highway is injecting spending.
财政政策：利用政府支出和税收影响经济。扩张性财政政策（增加支出、减税）刺激 AD；紧缩政策给过热的经济降温。政府修建新公路就是在注入支出。
Monetary Policy: Managing the money supply and interest rates, typically by a central bank. Lowering the policy rate makes borrowing cheaper, encouraging consumption and investment. Quantitative easing is an unconventional tool that buys bonds to inject liquidity.
货币政策：管理货币供应和利率，通常由央行执行。降低政策利率使借贷更便宜，鼓励消费和投资。量化宽松是一种非常规工具，购买债券以注入流动性。
Supply-side Policy: Measures aimed at increasing the productive capacity (LRAS) of the economy, such as improving education, cutting red tape, and investing in infrastructure. Think of it as upgrading the economic engine rather than just pressing the accelerator.
供给面政策：旨在提高经济生产能力 (LRAS) 的措施，如改善教育、减少繁文缛节和投资基础设施。把这想象成升级经济引擎，而不仅是踩油门。
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