📚 AS AQA Economics: Key Term Memory Guide | AS AQA 经济：核心术语速记指南
Mastering the vocabulary of AS AQA Economics is half the battle. From 'scarcity' to 'supply-side policy', the precise language of exams requires instant recall. This guide pairs every essential term with a straightforward definition, a memory shortcut, and a paired Chinese translation to strengthen your bilingual understanding and recall speed.
掌握 AS AQA 经济学的词汇是成功的一半。从“稀缺性”到“供给侧政策”，考试要求你能够精确地瞬间调用术语。本指南将每个核心术语与简明定义、记忆捷径以及配对的中文翻译结合起来，以强化你的双语理解和记忆速度。
1. Scarcity, Choice and Opportunity Cost | 稀缺性、选择与机会成本
The fundamental economic problem: finite resources cannot satisfy infinite human wants. This scarcity forces societies to answer 'What to produce?', 'How to produce?' and 'For whom to produce?'. Think of it as a birthday cake that can never be big enough for all the guests.
基本经济问题：有限的资源无法满足无限的人类欲望。这种稀缺性迫使社会回答“生产什么？”、“如何生产？”和“为谁生产？”的问题。可以想象成一块永远不够所有客人分的生日蛋糕。
Opportunity cost is the value of the next best alternative forgone whenever a choice is made. It isn't just money; it's time, enjoyment, or any missed option. Remember: 'choice breeds loss' — every 'yes' is a 'no' to something else.
机会成本是每次做出选择时所放弃的次优选项的价值。它不仅是金钱，还包括时间、享乐或任何错失的选择。记住：“选择滋生损失”——每一个“是”都是对其他事物的“否”。
Economic goods are scarce items that command a price, while free goods (like air, sunlight) are abundant and have zero opportunity cost at the margin. In exams, always ask: 'Does obtaining one extra unit involve a sacrifice?'
经济物品是稀缺且标价的物品，而免费物品（如空气、阳光）是丰富的，且其边际机会成本为零。在考试中，永远要问自己：“多获得一单位是否需要牺牲？”
2. Production Possibility Frontiers | 生产可能性边界
A PPF shows the maximum combinations of two goods an economy can produce with existing resources and technology. Points on the curve are efficient; inside signals unemployed resources. Visualise a downward-sloping arc as the country's 'menu of possibilities'.
生产可能性边界展示了在现有资源与技术下，一个经济体能生产的两种商品的最大组合。曲线上的点是有效率的；曲线内侧则表示存在未利用资源。把这条向下倾斜的弧线想象成该国的“可能性菜单”。
Moving along the PPF illustrates opportunity cost — to get more consumer goods, you must give up some capital goods. The curve is usually bowed outward due to increasing opportunity cost, meaning resources are not equally suited to all outputs.
沿着 PPF 移动就能说明机会成本——要获得更多消费品，就必须放弃一些资本品。曲线通常因机会成本递增而向外凸出，这意味着资源并非同样适合所有产出。
Economic growth shifts the PPF outward, enabled by more resources, better technology, or improved productivity. A classic exam tip: distinguish between 'actual growth' (moving from inside to on the curve) and 'potential growth' (shifting the curve itself).
经济增长会推动 PPF 向外移动，这得益于更多资源、更先进的技术或生产力的提升。经典应试提示：要区分“实际增长”（从曲线内侧移向曲线上）与“潜在增长”（曲线本身的移动）。
3. Demand, Supply and Market Equilibrium | 需求、供给与市场均衡
The law of demand: as price rises, quantity demanded falls, ceteris paribus. The demand curve slopes down because of income and substitution effects. Touch your index finger down a slope — 'price up, finger down' — to lock in the direction.
需求定律：在其他条件不变下，价格上升，需求量下降。需求曲线向下倾斜，这归因于收入效应和替代效应。用食指顺着斜坡向下的动作——“价格上涨，手指向下”——锁定方向。
The law of supply: as price rises, quantity supplied increases. Producers are motivated by profit signals. Draw an upward sloping curve with your hand: 'price up, quantity supplied up'.
供给定律：价格上升，供给量增加。生产者受利润信号的驱动。用手画出向上倾斜的曲线：“价格上涨，供给量向上”。
Market equilibrium occurs where demand equals supply, clearing the market at a certain price. Excess demand pushes price up; excess supply pulls price down. Think of a see-saw that always tilts back to the middle.
市场均衡发生在需求等于供给之处，以某一价格出清市场。超额需求推动价格上升；超额供给拉低价格。想象一个跷跷板，它总是重新倾斜回中间。
4. Price, Income and Cross Elasticities of Demand | 需求的价格、收入与交叉弹性
Price elasticity of demand (PED) measures responsiveness of quantity demanded to a price change. Formula:
PED = %ΔQd ÷ %ΔP
需求的价格弹性（PED）衡量需求量对价格变动的反应程度。公式：
PED = %ΔQd ÷ %ΔP
If PED > 1 demand is elastic; if PED < 1 it's inelastic. Mnemonic: 'Elastic stretches a lot' — a large quantity response per price change. A flat demand curve whispers 'I'm elastic'.
若 PED 大于 1，需求富有弹性；若小于 1，则缺乏弹性。记忆法：“弹性会大幅拉伸”——每单位价格变动会引起较大数量反应。一条扁平的需求曲线在轻声说“我是弹性的”。
Income elasticity (YED): %ΔQd ÷ %ΔY. Positive for normal goods, negative for inferior goods. A quick test: 'As your income rises, do you buy more of it?' If you'd switch from instant noodles to steak, the noodles have negative YED.
收入弹性（YED）：%ΔQd ÷ %ΔY。正常品为正，低档品为负。一个小测试：“当你的收入增加时，你会更多地购买它吗？”如果你会从方便面转向牛排，方便面就具有负的 YED。
Cross elasticity (XED): %ΔQd of good A ÷ % Positive → substitutes, negative → complements. Close your eyes and imagine tea and coffee — a coffee price hike makes tea demand soar, so XED positive.
交叉弹性（XED）：A 品需求量变化百分比除以 B 品价格变化百分比。正值→替代品，负值→互补品。闭上眼睛想象茶与咖啡——咖啡涨价让茶的需求飙升，因此 XED 为正。
5. Price Elasticity of Supply | 供给的价格弹性
Price elasticity of supply (PES) captures producers' ability to raise output after a price change. Formula:
PES = %ΔQs ÷ %ΔP
供给的价格弹性（PES）描述的是价格变动后生产者提高产出的能力。公式：
PES = %ΔQs ÷ %ΔP
Key determinants include time period, spare capacity, and ease of storage. In the short run, supply is often inelastic because firms are stuck with fixed capacity — think of a theatre that can't instantly add seats.
主要决定因素包括时间周期、闲置产能和储存的难易度。短期中，供给通常缺乏弹性，因为企业困于固定产能——好比一家剧院无法立刻增加座位。
In the long run all factors are variable, so PES becomes highly elastic. Visualise a factory that eventually builds a new wing: time unlocks flexibility.
长期中所有要素均可变，因此 PES 变得非常富有弹性。想象一家工厂最终建起新厂房：时间释放了灵活性。
6. Market Failure: Externalities | 市场失灵：外部性
Market failure means the price mechanism leads to a misallocation of resources. Externalities are spillover effects on third parties. Negative externalities (smoking, pollution) create overconsumption; positive externalities (education, vaccines) cause underconsumption.
市场失灵意味着价格机制导致资源配置失当。外部性是强加给第三方的溢出效应。负外部性（吸烟、污染）造成过度消费；正外部性（教育、疫苗）造成消费不足。
loss is the triangle between social optimum and free market equilibrium. Say to yourself: 'social cost bigger → too much; social benefit bigger → too little.'
对于任何外部性，画出区分私人曲线与社会曲线的图表。福利损失就是社会最优产量与自由市场均衡之间的三角形。对自己说：“社会成本更大→太多；社会利益更大→太少”。
7. Public Goods and Information Gaps | 公共物品与信息不对称
Public goods are non-rival (one person's consumption doesn't reduce availability) and non-excludable (cannot stop free-riders). Street lighting is the classic example. The free-rider problem means the market will underprovide these goods, so the government often steps in.
公共物品具有非竞争性（一个人的消费不会减少可用性）和非排他性（无法阻止搭便车者）。路灯是经典例子。搭便车问题意味着市场会供给不足，因此政府常常介入。
Information gaps: buyers or sellers lack full knowledge, leading to poor decisions. Merit goods (like education) are undervalued; demerit goods (like alcohol) are over-consumed because people misjudge long-term harm. Use the catchphrase: 'If we knew better, we'd choose differently.'
信息差距：买方或卖方缺乏充分知识，导致决策失误。优值品（如教育）被低估；劣值品（如酒精）则因人们错判长期危害而被过度消费。用这句话：“如果我们了解得更多，就会做出不同选择。”
8. Government Intervention and Government Failure | 政府干预与政府失灵
To correct market failure, governments use indirect taxes (raise price of demerit goods), subsidies (lower price of merit goods), maximum/minimum prices, and regulation. Pigovian tax equals the value of the negative externality — think of it as 'making the polluter pay'.
为纠正市场失灵，政府使用间接税（提高劣值品价格）、补贴（降低优值品价格）、最高/最低限价以及管制。庇古税等于负外部性的价值——可以理解为“让污染者付费”。
Government failure arises when intervention worsens the original misallocation. Causes include information failures, unintended consequences, and administrative costs. A farming subsidy meant to help smallholders might inflate land prices instead. Always evaluate — who really gains?
当干预使原有的配置失当恶化时，就出现了政府失灵。原因包括信息失灵、意料之外的后果以及行政成本。一项旨在帮助小农户的补贴反而可能推高土地价格。始终要评估——究竟谁受益？
9. Macroeconomic Indicators: GDP, Inflation, Unemployment | 宏观经济指标：GDP、通胀、失业
Gross Domestic Product (GDP) measures the total value of output produced within an economy. Real GDP strips out inflation, so it's the 'truth-teller' of growth. GDP per capita divides this by population, giving a rough measure of living standards.
国内生产总值（GDP）衡量一个经济体内产出的总价值。实际 GDP 剔除了通胀，因此才是增长的“真相讲述者”。人均 GDP 将其除以人口，提供了一国生活水平的粗略度量。
Inflation is a sustained rise in the general price level, tracked by CPI or RPI in the UK. Think of your basket of goods swelling in price each month. The Bank of England's target is 2% CPI — a low, stable flame, not a bonfire.
通货膨胀是整体物价水平的持续上升，在英国由 CPI 或 RPI 追踪。想象你的一篮子商品价格每月都在膨胀。英格兰银行的目标是 2% 的 CPI 通胀——一个低而稳定的火焰，绝不是篝火。
Unemployment counts those actively seeking work but without a job. The Claimant Count measures benefit claimants, while the Labour Force Survey is broader. Memorise: 'If you're not looking, you're not counted — but you're still an unused resource.'
失业统计的是那些积极寻找工作却没有工作的人。申请失业金人数统计的是申领救济金的人，而劳动力调查则更广泛。记住：“你不找工作，就不被计入——但你依然是未利用的资源。”
10. Aggregate Demand and the Multiplier | 总需求与乘数
Aggregate demand (AD) is total planned spending: AD = C + I + G + (X − M) — Consumption, Investment, Government spending, and net exports. Build a phrase to memorise: 'Cats In Gardens eXpect Mice'. It reminds you of the components quickly.
总需求（AD）是计划支出的总和：AD = C + I + G + (X − M)——消费、投资、政府支出和净出口。编个短语来记忆：“Cats In Gardens eXpect Mice”，这能让你快速回忆起各个组成部分。
The multiplier effect: an initial injection of spending leads to a larger final increase in national income. The formula:
k = 1 ÷ (1 − MPC) = 1 ÷ MPS
乘数效应：一次初始支出注入会导致国民收入更大幅度的增加。公式：
k = 1 ÷ (1 − MPC) = 1 ÷ MPS
MPC is the marginal propensity to consume — a larger multiplier (5) than a low MPC (0.2 → multiplier 1.25). Keep this in your pocket: 'Spend more, ripple bigger.'
MPC 是边际消费倾向——你把额外收入的多少比例用于消费。较高的 MPC（0.8）会产生较大的乘数（5），而较低的 MPC（0.2 → 乘数为 1.25）。记住这句话：“消费越多，涟漪越大”。
11. Aggregate Supply and Macroeconomic Equilibrium | 总供给与宏观经济均衡
Short-run aggregate supply (SRAS) slopes up because as prices rise, input costs like wages may be sticky, making it temporarily profitable to expand output. Any factor that reduces costs (lower commodity prices) shifts SRAS right.
短期总供给（SRAS）向上倾斜，因为当价格上涨时，工资等投入成本可能具有粘性，这使扩大产出暂时更有利可图。任何降低成本的因素（如大宗商品价格下跌）都会使 SRAS 右移。
Long-run aggregate supply (LRAS) represents the productive capacity of the economy. Classical LRAS is vertical at the full-employment level; Keynesians see a horizontal section when resources are idle. Draw an L-shape for Keynesian LRAS — 'flat when empty, vertical when full.'
长期总供给（LRAS）代表经济体的生产能力。古典学派的 LRAS 是在充分就业水平处的垂直线；凯恩斯主义者认为当资源闲置时，LRAS 有一段水平部分。画一个 L 形来表示凯恩斯 LRAS——“空闲时平坦，满载时垂直”。
AD and AS. A negative supply shock (oil price spike) shifts SRAS left, causing stagflation — rising prices and falling output. Connect the dots: 'SRAS left = cost-push inflation + recession.'
宏观经济均衡是 AD 与 AS 的交点。一次负向供给冲击（油价飙升）会使 SRAS 左移，导致滞胀——物价上涨而产出下降。把点连起来：“SRAS 左移 = 成本推动型通胀 + 经济衰退”。
12. Fiscal, Monetary and Supply-Side Policies | 财政、货币与供给侧政策
Fiscal policy uses government spending and taxation to influence AD. Expansionary measures (cut tax, raise G) boost AD; contractionary measures cool an overheating economy. Think of the chancellor pulling levers marked 'G' and 'T' to smooth the business cycle.
财政政策利用政府支出与税收来影响总需求。扩张性措施（减税、增加 G）会刺激 AD；紧缩性措施则给过热的经济降温。想象财政大臣拉动标有“G”和“T”的杠杆，以熨平经济周期。
Monetary policy is run by the central bank, adjusting interest rates and money supply. A lower bank rate cheapens borrowing, lifts investment and consumer spending. Quantitative easing (QE) creates new money to buy bonds, flooding the system with liquidity. No physical notes — it's all electronic.
货币政策由中央银行运作，通过调整利率和货币供给来实现。降低基准利率会让借贷变便宜，拉动投资和消费支出。量化宽松（QE）创造新货币来购买债券，向金融体系注入大量流动性。不存在实体纸钞——全是电子操作。
Supply-side policies target LRAS, aiming to raise productivity and potential output. Examples: education spending, tax reforms, privatisation, and deregulation. They are the 'build a bigger factory' approach, shifting both LRAS and the PPF outward over time. Link word: 'capacity'.
供给侧政策瞄准 LRAS，旨在提高生产率和潜在产出。例如：教育投入、税制改革、私有化和放松管制。这些是“建更大的工厂”的思路，随时间推移将 LRAS 和 PPF 向外推移。关键词：“产能”。
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