📚 IGCSE WJEC Economics: Last-Minute Revision Notes | IGCSE WJEC 经济：考前冲刺笔记
This is your ultimate last-minute revision guide for the IGCSE WJEC Economics exam. It covers the most essential concepts, definitions, diagrams, and formulas you need to know. Use these notes to refresh your memory and clarify key ideas before the test.
这是你 IGCSE WJEC 经济考前终极冲刺指南，涵盖所有必须掌握的核心概念、定义、图表和公式。考前用这些笔记回顾知识，理清思路。
1. The Basic Economic Problem & Scarcity | 基本经济问题与稀缺性
The fundamental economic problem is that resources are scarce, but human wants are unlimited. This creates the need for choice and opportunity cost.
基本经济问题是，资源是稀缺的，而人的欲望是无限的。这导致人们必须做出选择，并产生机会成本。
The four factors of production are land, labour, capital, and enterprise. Land includes natural resources, labour is human effort, capital is man-made goods used in production, and enterprise is the risk-taking ability of entrepreneurs.
四大生产要素是土地、劳动力、资本和企业家才能。土地包括自然资源，劳动力是人的努力，资本是生产中使用的人造物品，企业家才能是企业家承担风险的能力。
Goods can be classified as free goods (air, sunshine) and economic goods (scarce goods that command a price).
物品可分为免费品（如空气、阳光）和经济品（有价格的稀缺物品）。
2. Opportunity Cost & Production Possibility Curve | 机会成本与生产可能性曲线
Opportunity cost is the next best alternative forgone when a choice is made. It is a central concept because every decision involves a sacrifice.
机会成本是指当做出选择时所放弃的次优选项。这是一个核心概念，因为每一个决定都涉及某种牺牲。
The Production Possibility Curve (PPC) shows the maximum combinations of two goods an economy can produce with existing resources and technology. Points on the curve represent full and efficient employment of resources; points inside show unemployment or inefficiency; points outside are unattainable.
生产可能性曲线 (PPC) 表示一个经济体在现有资源和技术条件下所能生产的两种商品的最大组合。曲线上的点代表资源充分利用且有效率；曲线内的点表示未充分就业或低效；曲线外的点暂不可达。
Economic growth can be shown by an outward shift of the PPC, caused by an increase in the quantity or quality of resources or technological progress.
经济增长表现为 PPC 向外移动，原因在于资源数量或质量的提升，或是技术进步。
3. Demand & Supply | 需求与供给
The law of demand states that, ceteris paribus, as the price of a good rises, the quantity demanded falls (and vice versa). This is represented by a downward-sloping demand curve.
需求定律指出，在其他条件不变的情况下，商品价格上升时需求量下降（反之亦然）。这表现为一条向右下方倾斜的需求曲线。
Factors that shift the demand curve include changes in income, tastes, prices of substitutes and complements, population, and advertising. (Use the mnemonic PIRATES: Population, Income, Related goods, Advertising, Tastes, Expectations, Seasons.)
引起需求曲线移动的因素包括收入变化、偏好、替代品和互补品价格、人口和广告等。（记忆口诀：人口、收入、相关物品、广告、偏好、预期、季节。）
The law of supply shows that, ceteris paribus, as price rises, the quantity supplied increases. The supply curve slopes upward. Shifts in supply are caused by changes in production costs, technology, taxes, subsidies, weather, and number of sellers.
供给定律表明，在其他条件不变时，价格上升，供给量增加。供给曲线向上倾斜。供给曲线的移动由生产成本、技术、税收、补贴、天气和销售者数量等因素引起。
4. Elasticity (PED, PES, YED) | 弹性（需求价格弹性、供给价格弹性、需求收入弹性）
Price elasticity of demand (PED) measures how responsive quantity demanded is to a change in price.
需求价格弹性 (PED) 衡量需求量对价格变化的反应程度。
PED = %ΔQd / %ΔP
If PED > 1, demand is elastic; if PED < 1, demand is inelastic; if PED = 1, it is unit elastic. Knowledge of PED helps firms predict revenue changes: raising price increases revenue if demand is inelastic, but lowers it if demand is elastic.
若 PED > 1，需求富有弹性；若 PED < 1，需求缺乏弹性；若 PED = 1，则为单位弹性。了解 PED 有助于企业预测收入变动：若需求缺乏弹性，提价会增加收入；若富有弹性，提价则会减少收入。
Price elasticity of supply (PES) = %ΔQs / %ΔP. It depends on the time period, availability of resources, and spare capacity. Income elasticity of demand (YED) = %ΔQd / %ΔY. Normal goods have positive YED; inferior goods have negative YED.
供给价格弹性 PES = %ΔQs / %ΔP，取决于时间长短、资源可得性和闲置产能。需求收入弹性 YED = %ΔQd / %ΔY。正常品的 YED 为正，低档品为负。
5. Market Equilibrium & Price Mechanism | 市场均衡与价格机制
Market equilibrium occurs where the demand and supply curves intersect. At this point, the quantity demanded equals the quantity supplied, and there is no tendency for price to change.
市场均衡出现在需求曲线与供给曲线的交点。此时需求量等于供给量，价格没有变动的趋势。
If the market price is above equilibrium, a surplus arises and price is pushed down. If price is below equilibrium, a shortage occurs and price is pushed up. The price mechanism automatically allocates scarce resources through the signals of prices.
若市场价格高于均衡，会出现过剩，价格被压低；若低于均衡，则出现短缺，价格被推高。价格机制通过价格信号自动配置稀缺资源。
The functions of the price mechanism are: signalling, incentive, and rationing. Rising prices signal producers to produce more and consumers to economise. They also ration scarce goods to those able and willing to pay.
价格机制的功能包括：传递信号、提供激励和配给。价格上涨向生产者发出增产信号，同时促使消费者节约；价格还能将稀缺商品配给到有支付意愿的人手中。
6. Market Failure & Externalities | 市场失灵与外部性
Market failure occurs when the free market fails to allocate resources efficiently, leading to a net social welfare loss. Key causes include externalities, public goods, information gaps, and monopoly power.
市场失灵是指自由市场未能有效配置资源，导致社会净福利损失。主要原因包括外部性、公共物品、信息不对称和垄断势力。
Negative externalities (e.g., pollution from factories) cause overproduction because private cost is lower than social cost. Positive externalities (e.g., education, vaccinations) lead to underproduction since social benefit exceeds private benefit.
负外部性（如工厂污染）造成过度生产，因为私人成本低于社会成本。正外部性（如教育、疫苗）导致生产不足，因为社会收益大于私人收益。
Public goods are non-rival and non-excludable, meaning the free market will not provide them at all (the free-rider problem). Street lighting and national defence are classic examples.
公共物品具有非竞争性和非排他性，自由市场不会主动提供（搭便车问题）。路灯和国防是典型例子。
7. Government Intervention (Taxes, Subsidies, Price Controls) | 政府干预（税收、补贴、价格管制）
To correct market failure, governments impose indirect taxes on goods with negative externalities (e.g., sugar tax on soft drinks) to internalise the externality and reduce consumption.
为矫正市场失灵，政府对具有负外部性的商品（如汽水糖税）征收间接税，以内部化外部成本，减少消费。
Subsidies are given to goods with positive externalities (e.g., renewable energy, education) to lower price and increase output. Maximum prices (price ceilings) are set below equilibrium to protect consumers (e.g., rent controls), but may create shortages. Minimum prices (price floors) are set above equilibrium to protect producers (e.g., minimum wage, agricultural support), but may lead to surpluses.
补贴给予具有正外部性的商品（如可再生能源、教育），以降低价格、增加产出。最高限价（价格上限）设定在均衡下方以保护消费者（如租金管制），但可能造成短缺。最低限价（价格下限）设定在均衡上方以保护生产者（如最低工资、农业支持），但可能导致过剩。
8. Macroeconomic Objectives & Indicators | 宏观经济目标与指标
Governments aim to achieve low and stable inflation, sustainable economic growth, low unemployment, and a satisfactory balance of payments. These are often called the ‘four horsemen’ of macro objectives.
政府力求实现低而稳定的通胀、可持续经济增长、低失业率和良好的国际收支平衡。这些常被称为宏观经济目标的“四骑士”。
GDP measures the total value of goods and services produced in a country in a year. Real GDP adjusts for inflation, making it a better gauge of living standards. Unemployment rate = (unemployed / labour force) × 100%. Inflation is measured by the Consumer Price Index (CPI).
GDP 衡量一国一年内生产的总产出。实际 GDP 剔除了通胀影响，更能反映生活水平。失业率 = （失业人数 / 劳动力人数）× 100%。通胀通过消费者价格指数 (CPI) 衡量。
Conflicts between objectives exist: for example, rapid growth may cause demand-pull inflation, and policies to reduce inflation may raise unemployment in the short run.
政策目标之间存在冲突：如快速经济增长可能引起需求拉动型通胀，而抑制通胀的政策在短期可能推高失业率。
9. Fiscal & Monetary Policy | 财政与货币政策
Fiscal policy involves changes in government spending and taxation to influence the economy. Expansionary fiscal policy (higher spending or lower taxes) boosts aggregate demand; contractionary policy (lower spending or higher taxes) dampens it.
财政政策通过调整政府支出和税收来影响经济。扩张性财政政策（增支或减税）刺激总需求；紧缩性政策（减支或增税）抑制总需求。
A government budget can be balanced, in surplus (tax > spending), or in deficit (spending > tax). Persistent deficits add to national debt.
政府预算可能是平衡的，有盈余（税收 > 支出），或有赤字（支出 > 税收）。持续的赤字会增加国债。
Monetary policy is controlled by the central bank, mainly through the interest rate and quantitative easing. Lower interest rates encourage borrowing and spending, while higher rates cool down an overheating economy. The money supply can also be adjusted.
货币政策由中央银行实施，主要通过利率和量化宽松进行。降息鼓励借贷和消费，加息则为过热经济降温。货币供应量也可调节。
10. International Trade & Protectionism | 国际贸易与保护主义
Countries trade because of comparative advantage: the ability to produce a good at a lower opportunity cost than another country. Specialisation and trade increase global output and consumption possibilities.
各国进行贸易的理论基础是比较优势：以低于另一国的机会成本生产某种商品的能力。专业化和贸易可增加全球产出和消费可能性。
Free trade brings benefits such as lower prices, greater choice, economies of scale, and technology transfer. However, some groups may lose jobs, leading to calls for protectionism.
自由贸易带来低价、更多选择、规模经济和技术转移等好处。但部分群体会丧失就业，从而引发保护主义呼声。
Protectionist measures include tariffs (tax on imports), quotas (physical limits on import quantity), subsidies for domestic firms, and non-tariff barriers (regulations). These measures harm consumer welfare and global efficiency.
保护主义措施包括关税（进口税）、配额（进口数量限制）、对本国企业的补贴和非关税壁垒（法规）。这些措施损害消费者福利和全球效率。
11. Exchange Rates & Balance of Payments | 汇率与国际收支
The exchange rate is the price of one currency in terms of another. It can be determined by market forces (floating) or fixed by a government (pegged). Appreciation makes exports dearer and imports cheaper; depreciation has the opposite effect.
汇率是以另一种货币表示的一种货币的价格。它可以由市场力量决定（浮动），或由政府固定（钉住）。升值使出口变贵、进口变便宜；贬值则相反。
The balance of payments records all economic transactions between a country and the rest of the world. The current account includes trade in goods (visible), trade in services (invisible), income flows, and transfers. A deficit on the current account must be matched by a surplus on the financial/capital account.
国际收支记录一国与世界其他地区之间的所有经济交易。经常账户包括货物贸易（有形）、服务贸易（无形）、收入流动和转移支付。经常账户赤字必须由金融/资本账户盈余来平衡。
Persistent current account deficits may indicate a lack of international competitiveness and could lead to currency depreciation and foreign debt.
持续的经常账户赤字可能表明缺乏国际竞争力，并可能导致本币贬值和外债累积。
12. Exam Technique & Key Diagrams | 考试技巧与关键图表
In WJEC IGCSE Economics, diagrams are vital. Always label axes, curves, equilibrium points, and shaded areas. Common diagrams include: demand and supply with shifts, PPC, externalities (showing welfare loss triangle), incidence of tax/subsidy, and the circular flow of income.
在 WJEC IGCSE 经济考试中，图表至关重要。务必标注坐标轴、曲线、均衡点以及阴影区域。常见图表包括：供求曲线移动、PPC、外部性（显示福利损失三角形）、税收/补贴分担以及收入循环流动图。
Define key terms precisely at the start of an answer. Use chains of reasoning: ‘If X increases, then Y… leading to Z.’ For evaluation questions, give at least two sides and a justified conclusion.
作答时先精确界定关键术语。使用推理链条：“如果 X 增加，则 Y……导致 Z。” 对于评估类问题，至少给出正反两方面观点，并做出有依据的结论。
Time management: allocate roughly one minute per mark. Read the command words carefully: ‘explain’ means show cause and effect, ‘analyse’ means break down into components, ‘evaluate’ means weigh up and conclude. Use data and extracts from the stimulus material wherever possible.
时间管理：大约一分值分配一分钟。仔细审读指令词：“解释”要展示因果关系，“分析”要分解剖析，“评估”要权衡并得出结论。尽可能使用所给材料中的数据和摘要。
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