📚 Microeconomics Key Terms Explained & Selected Exam Vocabulary | 微观经济学术语释义与真题词汇精选
Microeconomics examines the behaviour of individual economic agents—consumers, firms, and industries—and how their decisions shape the allocation of scarce resources. Understanding key terms is essential for analysing markets, evaluating policy, and scoring high on exams. This article defines core microeconomic concepts and curates a selection of exam-relevant vocabulary frequently tested in A-Level and equivalent syllabi.
微观经济学研究消费者、企业和行业等个体经济行为者的决策，以及这些决策如何塑造稀缺资源的配置。理解关键术语对于分析市场、评估政策并在考试中取得高分至关重要。本文界定核心微观经济学概念，并精选常出现在A-Level及同等大纲真题中的高频词汇。
1. Scarcity and Choice | 稀缺性与选择
Scarcity refers to the fundamental economic problem: limited resources cannot satisfy all human wants. Because resources are finite, economic agents must make choices, each of which involves an opportunity cost—the value of the next best alternative forgone. The basic economic questions arising from scarcity are “what to produce”, “how to produce”, and “for whom to produce”.
稀缺性指向根本的经济学问题：有限的资源无法满足所有人类欲望。由于资源是有限的，经济主体必须做出选择，而每一次选择都涉及机会成本——即所放弃的次优选择的价值。由稀缺性产生的基本经济问题是“生产什么”、“如何生产”以及“为谁生产”。
Factors of production are the inputs used to produce goods and services: land, labour, capital, and entrepreneurship. A rational choice involves weighing marginal benefits against marginal costs to maximise utility or profit.
生产要素是用于生产商品和服务的投入：土地、劳动力、资本和企业家才能。理性选择涉及在边际上权衡收益与成本以最大化效用或利润。
| Key Term | 中文释义 |
| Scarcity | 稀缺性 |
| Opportunity cost | 机会成本 |
| Trade-off | 权衡取舍 |
| Factors of production | 生产要素 |
| Capital | 资本 |
| Entrepreneurship | 企业家才能 |
2. Demand and the Law of Demand | 需求与需求定律
Demand is the quantity of a good or service that consumers are willing and able to purchase at various prices over a given period, ceteris paribus. The law of demand states that, all else equal, as the price of a good rises, the quantity demanded falls, resulting in a downward-sloping demand curve. This is driven by the income effect (a higher price reduces real purchasing power) and the substitution effect (consumers switch to relatively cheaper alternatives).
需求是指在某一时期内，在其他条件不变的情况下，消费者愿意且能够以不同价格购买的商品或服务的数量。需求定律指出，在其他条件不变时，商品价格上升，需求量下降，从而形成向下倾斜的需求曲线。这由收入效应（价格上升降低实际购买力）和替代效应（消费者转向相对更便宜的替代品）驱动。
A change in price causes a movement along the demand curve (a change in quantity demanded), whereas changes in non-price factors—such as income, tastes, the price of related goods, expectations, and the number of buyers—shift the entire demand curve. A normal good sees demand rise with income; an inferior good sees demand fall as income rises. Substitutes and complements also affect demand.
价格的变动导致需求量沿需求曲线移动（需求量变化），而非价格因素——如收入、偏好、相关商品价格、预期和买者数量——的变动则会让整条需求曲线移位。正常商品的需求随收入上升而增加；低档商品的需求随收入上升而减少。替代品和互补品也会影响需求。
| Key Term | 中文释义 |
| Demand | 需求 |
| Quantity demanded | 需求量 |
| Ceteris paribus | 其他条件不变 |
| Normal good | 正常商品 |
| Inferior good | 低档商品 |
| Substitute | 替代品 |
| Complement | 互补品 |
3. Supply and the Law of Supply | 供给与供给定律
Supply is the quantity of a good or service that producers are willing and able to offer for sale at each price over a given time period. The law of supply states that, ceteris paribus, a higher price leads to a higher quantity supplied, producing an upward-sloping supply curve. This reflects the profit motive: producers respond to price signals to increase output when it becomes more profitable to do so.
供给是指在一定时期内，生产者愿意且能够以不同价格提供出售的商品或服务的数量。供给定律指出，在其他条件不变时，价格越高，供给量越大，形成向上倾斜的供给曲线。这反映了利润动机：当生产变得更为有利可图时，生产者响应价格信号扩大产出。
A change in the good’s own price causes a movement along the supply curve, while changes in input costs, technology, taxes and subsidies, the number of sellers, and expectations shift the supply curve. Lower input costs or technological improvements increase supply, shifting the curve to the right.
商品自身价格的变动引起供给量沿供给曲线移动，而投入成本、技术、税收与补贴、卖者数量和预期等变动则会使供给曲线移位。更低的投入成本或技术进步会增加供给，使曲线向右平移。
| Key Term | 中文释义 |
| Supply | 供给 |
| Quantity supplied | 供给量 |
| Profit motive | 利润动机 |
| Input costs | 投入成本 |
4. Market Equilibrium and Disequilibrium | 市场均衡与非均衡
Market equilibrium occurs where the quantity demanded equals the quantity supplied at a particular price. At this equilibrium price, there is no inherent tendency for change—the market clears. If the market price is above equilibrium, excess supply (a surplus) emerges, putting downward pressure on price. If the price is below equilibrium, excess demand (a shortage) drives the price upward.
市场均衡发生在某一价格上需求量等于供给量之处。在这一均衡价格下，不存在内在的变动趋势——市场出清了。如果市场价格高于均衡，出现超额供给（盈余），给价格带来下行压力。如果价格低于均衡，超额需求（短缺）会推动价格上升。
The price mechanism performs three crucial functions: a rationing function (allocating scarce goods to those willing and able to pay), a signalling function (conveying information about changing market conditions), and an incentive function (encouraging producers and consumers to adjust behaviour).
价格机制履行三项关键职能：配给职能（将稀缺商品分配给愿意且能够支付的人）、信号职能（传递市场状况变化的信息）和激励职能（鼓励生产者和消费者调整行为）。
| Key Term | 中文释义 |
| Equilibrium price | 均衡价格 |
| Market clearing | 市场出清 |
| Excess demand | 超额需求 |
| Excess supply | 超额供给 |
| Price mechanism | 价格机制 |
5. Price Elasticity of Demand (PED) | 需求价格弹性
Price elasticity of demand measures the responsiveness of quantity demanded to a change in the price of the good itself. It is calculated as:
需求价格弹性衡量需求量对商品自身价格变动的反应敏感程度。其计算公式为：
PED = %Δ Qd / %Δ P
Since demand curves slope downward, PED is usually negative, but the absolute value is used for interpretation. Demand is price elastic when |PED| > 1, unit elastic when |PED| = 1, and price inelastic when |PED| < 1. When demand is elastic, a price increase reduces total revenue; when inelastic, a price increase raises total revenue.
由于需求曲线向下倾斜，PED通常为负值，但分析时使用其绝对值。当|PED| > 1时需求富有弹性，|PED| = 1时为单位弹性，|PED| < 1时缺乏弹性。当需求富有弹性时，提价会减少总收入；当需求缺乏弹性时，提价会增加总收入。
Key determinants include the availability of close substitutes, the proportion of income spent on the good, whether the good is a necessity or luxury, and the time period considered. Exam questions frequently ask students to calculate PED from data and interpret the revenue implications.
关键决定因素包括：相似替代品的可得性、商品在收入中所占比重、属于必需品还是奢侈品，以及分析的时间跨度。真题常要求根据数据计算PED并解释其对收入的影响。
| Key Term | 中文释义 |
| Price elasticity of demand | 需求价格弹性 |
| Elastic demand | 富有弹性需求 |
| Inelastic demand | 缺乏弹性需求 |
| Total revenue | 总收入 |
6. Price Elasticity of Supply (PES) | 供给价格弹性
Price elasticity of supply captures how responsive quantity supplied is to a change in the good’s price. Its formula:
供给价格弹性衡量供给量对商品自身价格变动的反应程度。其公式为：
PES = %Δ Qs / %Δ P
PES is typically positive because higher prices incentivise greater output. Supply is elastic when producers can easily adjust output (e.g., goods with low storage costs or short production times). It is inelastic when production faces capacity constraints, long lead times, or perishability issues. The time horizon is crucial: supply is more elastic in the long run as firms can vary all inputs.
PES通常为正值，因为更高的价格会激励增加产出。当生产者可以轻松调整产量时（例如储存成本低或生产周期短的商品），供给富有弹性。当生产面临产能约束、较长的前置时间或易腐性等问题时，供给缺乏弹性。时间范围至关重要：长期中企业可变动所有投入，供给更富有弹性。
| Key Term | 中文释义 |
| Price elasticity of supply | 供给价格弹性 |
| Elastic supply | 富有弹性供给 |
| Inelastic supply | 缺乏弹性供给 |
| Short run / long run | 短期 / 长期 |
7. Consumer and Producer Surplus | 消费者剩余与生产者剩余
Consumer surplus is the difference between what consumers are willing to pay (shown by the demand curve) and what they actually pay (the market price). Producer surplus is the difference between the price producers receive and the minimum price they would accept (the supply curve). Together, these surpluses measure total welfare in a market.
消费者剩余是消费者愿意支付的最高价格（由需求曲线显示）与实际支付价格（市场价格）之间的差额。生产者剩余是生产者获得的价格与它们愿意接受的最低价格（供给曲线）之差。两者之和衡量市场的总福利。
At competitive equilibrium, total surplus is maximised. Government interventions like price ceilings or price floors can create deadweight loss—a reduction in total surplus that is not transferred to anyone. Understanding surplus helps evaluate the net social benefits of policies.
在竞争均衡下，总剩余达到最大。政府干预如价格上限或价格下限可能造成无谓损失——总剩余的减少且未转移给任何人。理解剩余有助于评估政策的净社会收益。
| Key Term | 中文释义 |
| Consumer surplus | 消费者剩余 |
| Producer surplus | 生产者剩余 |
| Welfare | 福利 |
| Deadweight loss | 无谓损失 |
8. Externalities and Market Failure | 外部性与市场失灵
An externality occurs when the production or consumption of a good affects a third party not directly involved in the transaction, and this effect is not reflected in market prices. A negative externality (e.g., factory emissions) imposes external costs, causing over-production relative to the socially optimal level. A positive externality (e.g., vaccination) generates external benefits, leading to under-consumption.
当一种商品的生产或消费影响到未直接参与交易的第三方，且该影响未反映在市场价格中时，就产生了外部性。负外部性（如工厂排放）施加了外部成本，导致相对于社会最优水平的过度生产。正外部性（如疫苗接种）带来外部收益，导致消费不足。
Social cost equals private cost plus external cost; social benefit equals private benefit plus external benefit. Market failure arises when the free market fails to allocate resources efficiently. Governments can correct externalities through Pigouvian taxes (to internalise external costs) or subsidies, as well as regulation and tradable permits.
社会成本等于私人成本加上外部成本；社会收益等于私人收益加上外部收益。当自由市场无法有效配置资源时，便出现市场失灵。政府可以通过庇古税（将外部成本内部化）或补贴，以及监管和可交易许可证等手段纠正外部性。
| Key Term | 中文释义 |
| Externality | 外部性 |
| Private cost / benefit | 私人成本 / 收益 |
| Social cost / benefit | 社会成本 / 收益 |
| Pigouvian tax | 庇古税 |
| Market failure | 市场失灵 |
9. Public Goods and Common Resources | 公共物品与公共资源
Public goods are non-excludable (it is impossible to prevent non-payers from consuming them
Published by TutorHao | Economics Revision Series | aleveler.com
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