📚 Core Knowledge Review for Pre-U AQA Economics | Pre-U AQA 经济：核心知识点梳理
Pre-U AQA Economics builds a strong foundation in both microeconomic and macroeconomic principles. This article presents a structured overview of the core topics you must master: from the basic economic problem to international trade. Understanding these concepts will enable you to explain real-world economic phenomena, analyse policy decisions, and excel in exam questions that require clear definitions, diagrams, and evaluation.
Pre-U AQA 经济为微观与宏观经济学原理打下坚实基础。本文系统梳理了必考的核心知识点：从基本经济问题到国际贸易。掌握这些概念，你便能解释现实经济现象、分析政策决策，并在需要明确定义、图表与评估的考题中脱颖而出。
1. Scarcity and Choice | 稀缺性与选择
The fundamental economic problem is scarcity: unlimited wants but limited resources. Because resources are finite, societies must make choices about what to produce, how to produce, and for whom to produce.
经济学的基本问题是稀缺性：无限的欲望与有限的资源。由于资源的有限性，社会必须在生产什么、如何生产以及为谁生产这三个基本问题上做出选择。
Scarcity leads to opportunity cost, which is the value of the next best alternative forgone when a choice is made. All economic decisions involve a trade-off.
稀缺性导致机会成本，即做出一种选择时所放弃的次优选择的价值。所有经济决策都伴随着权衡取舍。
A production possibility frontier (PPF) illustrates the maximum combinations of two goods an economy can produce with given resources and technology. Points on the curve represent productive efficiency, while inward shifts indicate a fall in productive capacity.
生产可能性边界（PPF）用来展示在既定资源和技术下经济体所能生产的两种商品的最大组合。曲线上的点代表生产有效率，向内移动则表示生产能力的下降。
2. Demand and Supply | 需求与供给
Demand is the quantity of a good or service consumers are willing and able to buy at various prices over a period of time. The law of demand states that, ceteris paribus, as price falls, quantity demanded rises.
需求是指消费者在一定时期内、在不同价格水平下愿意且能够购买的商品或服务的数量。需求定律指出，在其他条件不变的情况下，价格下降，需求量上升。
Movements along the demand curve are caused by price changes, while shifts are caused by factors such as income, tastes, prices of substitutes and complements, and expectations. Supply is the quantity producers are willing and able to sell at various prices; the law of supply states that price and quantity supplied are positively related.
需求量的变动由价格变动引起，表现为沿需求曲线的移动；需求的变动则由收入、偏好、替代品与互补品价格、预期等因素引起，导致需求曲线平移。供给是生产者愿意且能够出售的数量；供给定律表明价格与供给量呈正相关。
Supply shifts can arise from changes in production costs, technology, taxes and subsidies, and the number of sellers.
供给曲线的移动可能源于生产成本变化、技术进步、税收与补贴、以及卖家数量的变化。
3. Elasticity | 弹性
Price elasticity of demand (PED) measures the responsiveness of quantity demanded to a change in price.
需求的价格弹性（PED）衡量需求量对价格变动的反应程度。
PED = %ΔQd ÷ %ΔP
If |PED| > 1, demand is elastic; if |PED| < 1, demand is inelastic; if |PED| = 1, demand is unit elastic. Determinants include availability of substitutes, degree of necessity, and the proportion of income spent on the good.
若 |PED| > 1，需求富有弹性；|PED| < 1，需求缺乏弹性；|PED| = 1，为单位弹性。其决定因素包括替代品的可得性、必需程度以及购买该商品占收入的比例。
Price elasticity of supply (PES) measures how responsive quantity supplied is to price changes. Key determinants are the time period and the flexibility of the production process.
供给的价格弹性（PES）衡量供给量对价格变动的反应程度。关键决定因素是时间周期和生产过程的灵活性。
Income elasticity of demand (YED) and cross elasticity of demand (XED) allow firms to predict the impact of income changes and competitors’ pricing. For example, a positive XED indicates substitute goods.
需求的收入弹性（YED）和交叉弹性（XED）帮助企业预测收入变化及竞争者定价的影响。例如，正的交叉弹性表明两种商品互为替代品。
4. Market Equilibrium and Price Mechanism | 市场均衡与价格机制
Market equilibrium occurs where quantity demanded equals quantity supplied, with no tendency for change. Excess demand pushes prices up; excess supply pushes prices down.
市场均衡出现在需求量等于供给量、没有内在变动趋势时。超额需求推动价格上涨；超额供给推动价格下降。
The price mechanism performs three functions: signalling, incentivising, and rationing. Rising prices signal producers to increase output and encourage consumers to economise, thereby allocating scarce resources.
价格机制执行三大功能：信号功能、激励功能和配给功能。价格上涨向生产者发出扩大生产的信号，同时促使消费者节约，从而实现稀缺资源的配置。
Consumer surplus is the difference between what consumers are willing to pay and what they actually pay. Producer surplus is the difference between the market price and the minimum price producers are willing to accept.
消费者剩余是消费者愿意支付的最高价格与实际支付价格之间的差额。生产者剩余是市场价格与生产者愿意接受的最低价格之间的差额。
5. Market Failure | 市场失灵
Market failure occurs when the free market fails to allocate resources efficiently, leading to a net welfare loss. Key types include externalities, public goods, information asymmetry, 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。主要类型包括外部性、公共品、信息不对称和垄断势力。
Negative production externalities (e.g., factory pollution) create external costs not reflected in the supply curve, causing overproduction. Positive consumption externalities (e.g., vaccinations) generate external benefits, leading to underconsumption.
生产负外部性（如工厂污染）产生未在供给曲线中体现的外部成本，导致过度生产。消费正外部性（如疫苗接种）带来外部收益，导致消费不足。
Public goods are non-rivalrous and non-excludable (e.g., street lighting). The free-rider problem means they would be underprovided without government intervention. Merit and demerit goods also suffer from information failure.
公共品具有非竞争性和非排他性（如路灯）。搭便车问题意味着若无政府干预，公共品将供给不足。优值品和劣值品也因信息不对称而遭遇消费问题。
6. Government Intervention | 政府干预
Governments correct market failures using indirect taxes (to internalise external costs), subsidies (to boost consumption of merit goods), regulation (e.g., pollution limits), and tradable pollution permits.
政府通过征收间接税（内部化外部成本）、提供补贴（促进优值品消费）、实施监管（如污染限额）以及可交易的污染许可证等手段纠正市场失灵。
Minimum and maximum price controls can address inequality or affordability but may cause shortages or surpluses. For example, a minimum wage set above equilibrium can lead to excess supply of labour (unemployment).
最低和最高价格管制可以解决不平等或可负担性问题，但可能引致短缺或过剩。例如，最低工资设定在均衡水平之上，可能导致劳动力超额供给（失业）。
Government failure may arise when intervention creates unintended consequences, such as regulatory capture, information gaps, or excessive administrative costs, leading to a net welfare loss.
政府失灵可能源自干预产生的意外后果，如监管俘获、信息缺口或过高的行政成本，最终造成净福利损失。
7. Macroeconomic Objectives | 宏观经济目标
The main macroeconomic objectives are sustainable economic growth, low and stable inflation, low unemployment, and a satisfactory balance of payments on current account. Governments may also target equitable income distribution and environmental sustainability.
宏观经济的主要目标包括可持续的经济增长、低而稳定的通胀、低失业率以及令人满意的国际收支经常项目。政府还可能追求收入分配公平和环境可持续性。
Economic growth is measured by the percentage change in real GDP. Short-run growth reflects the use of spare capacity, while long-run growth requires an expansion of the economy’s productive potential.
经济增长通过实际 GDP 的百分比变动衡量。短期增长反映了闲置产能的利用，而长期增长则需要经济潜在产能的扩张。
Inflation is measured by the Consumer Price Index (CPI). Demand-pull inflation arises from excessive aggregate demand, while cost-push inflation is caused by rising input costs.
通胀通过消费者价格指数（CPI）衡量。需求拉动型通胀源自总需求过度，成本推动型通胀则由投入成本上升引发。
Unemployment rates reflect the percentage of the labour force actively seeking work but unable to find it. Types include cyclical, structural, frictional, and seasonal unemployment.
失业率反映了劳动人口中积极寻找工作却无法就业的比例。失业类型包括周期性、结构性、摩擦性和季节性失业。
8. Aggregate Demand and Aggregate Supply | 总需求与总供给
Aggregate Demand (AD) is the total spending on domestic goods and services in an economy: AD = C + I + G + (X – M). A fall in any component shifts the AD curve leftwards, potentially causing a recession.
总需求（AD）是一个经济体中用于国内商品和服务的总支出：AD = C + I + G + (X – M)。任何一个组成部分下降都会使 AD 曲线左移，可能引发经济衰退。
Short-run Aggregate Supply (SRAS) slopes upward because higher output prices relative to input costs induce firms to expand production. Shifts can result from changes in wage rates, commodity prices, or indirect taxes.
短期总供给（SRAS）向右上方倾斜，因为相对于投入成本的更高产出价格会激励企业扩大生产。工资率、大宗商品价格或间接税的变化会导致 SRAS 曲线移动。
Long-run Aggregate Supply (LRAS) represents the economy’s potential output when all resources are fully employed. The classical LRAS is vertical, while the Keynesian LRAS has a horizontal segment at low output, reflecting spare capacity.
长期总供给（LRAS）代表所有资源得到充分利用时的潜在产出。古典学派的 LRAS 是垂直的，而凯恩斯学派的 LRAS 在低产出水平时有一段水平区域，反映存在闲置产能。
9. Macroeconomic Policy | 宏观经济政策
Fiscal policy involves changes in government spending and taxation. Expansionary fiscal policy (increased G or reduced T) boosts AD, while contractionary policy helps cool an overheating economy.
财政政策涉及政府支出与税收的调整。扩张性财政政策（增加 G 或减少 T）刺激 AD，而紧缩性政策有助于为过热的经济降温。
Monetary policy uses interest rates and the money supply to influence economic activity. A lower base rate reduces the cost of borrowing, encouraging consumption and investment. Quantitative easing (QE) aims to boost AD when interest rates are near zero.
货币政策通过调整利率和货币供给影响经济活动。降低基准利率减少了借贷成本，鼓励消费和投资。当利率接近零时，量化宽松（QE）旨在提振 AD。
Supply-side policies seek to increase the productive capacity of the economy by improving the quality and quantity of resources. Examples include education and training, tax reforms to incentivise work, and deregulation.
供给侧政策旨在通过提高资源的质量和数量来提升经济的生产能力。例子包括教育和培训、激励工作的税制改革以及放松管制。
Conflicts between objectives exist: for instance, boosting growth may worsen inflation and the current account deficit. Effective policy often requires a combination of tools and careful timing.
各目标之间存在冲突：例如，促进增长可能会加剧通胀和国际收支赤字。有效的政策通常需要工具组合与精准的时机把握。
10. International Trade and Exchange Rates | 国际贸易与汇率
International trade allows countries to specialise according to their comparative advantage, leading to greater global output and consumption. The theory of comparative advantage states that a country should produce goods where it has the lowest opportunity cost.
国际贸易使各国能根据其比较优势进行专业化生产，从而扩大全球产出与消费。比较优势理论指出，一国应生产机会成本最低的商品。
Protectionism, through tariffs, quotas, and non-tariff barriers, shields domestic industries but causes inefficiency and higher prices for consumers. Free trade areas and customs unions promote trade liberalisation.
通过关税、配额和非关税壁垒实施的贸易保护主义，虽保护了国内产业，却造成效率损失和消费者面临更高价格。自由贸易区和关税同盟推动着贸易自由化。
The balance of payments records all transactions between a country and the rest of the world. The current account includes trade in goods, services, primary income, and secondary income. A persistent deficit may indicate structural uncompetitiveness.
国际收支记录了一国与世界其他国家间的全部交易。经常账户包括商品贸易、服务贸易、初次收入和二次收入。持续的赤字可能表明结构性竞争力不足。
Exchange rates can be floating, fixed, or managed. A depreciation of the currency makes exports cheaper and imports dearer, thus altering AD and the trade balance, depending on the Marshall-Lerner condition.
汇率制度可以是浮动、固定或有管理的浮动。本币贬值使出口更便宜、进口更昂贵，从而改变 AD 和贸易差额，其效果取决于马歇尔-勒纳条件。
Published by TutorHao | Economics Revision Series | aleveler.com
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