📚 Core Knowledge Review for Year 9 Cambridge Economics | Year 9 Cambridge 经济：核心知识点梳理
This article summarises the essential topics covered in the first year of Cambridge IGCSE Economics. It is designed to help Year 9 students build a strong foundation in economic principles, from scarcity and choice to how markets work. Each section is presented in both English and Chinese to support bilingual learning and revision.
本文梳理了剑桥 IGCSE 经济第一学年的核心知识点，旨在帮助 Year 9 学生建立对经济学基本原理的扎实理解，从稀缺性与选择到市场运作机制。每个小节均提供中英双语讲解，便于双语学习与复习。
1. The Basic Economic Problem: Scarcity and Choice | 基本经济问题：稀缺性与选择
Economics is built on the fundamental idea that resources are limited, while human wants are unlimited. This situation is known as scarcity. Because we cannot have everything we desire, we must make choices about how to allocate our scarce resources. Every choice involves giving something up, which introduces the concept of opportunity cost.
经济学建立在一个根本观点之上：资源是有限的，而人类的欲望是无限的。这种情况被称为稀缺性。正因我们无法拥有想要的一切，就必须对如何分配稀缺资源做出选择。每一次选择都意味着放弃某些东西，这就引出了机会成本的概念。
The basic economic problem applies to all economic agents — individuals, firms, and governments. Individuals must decide how to spend their income, firms must choose what to produce with limited capital and labour, and governments face unlimited demand for public services against a limited budget. The central task of economics is to study how these choices are made and their consequences.
基本经济问题适用于所有经济主体——个人、企业和政府。个人必须决定如何花费收入，企业必须在有限的资本和劳动力下选择生产什么，而政府则面临有限的预算与无限的公共服务需求之间的矛盾。经济学的中心任务就是研究这些选择是如何做出的及其后果。
2. Factors of Production | 生产要素
To produce goods and services, an economy uses resources known as factors of production. There are four main factors: land, labour, capital, and enterprise. Each plays a distinct role in the production process and earns a corresponding reward.
为了生产商品和服务，经济需要使用被称为生产要素的资源。主要有四种要素：土地、劳动、资本和企业精神。每一种要素在生产过程中都扮演着独特的角色，并获得相应的报酬。
The table below summarises the factors of production and their rewards:
下表总结了生产要素及其报酬：
| Factor | 要素 | Definition | 定义 | Reward | 报酬 |
|---|---|---|
| Land | 土地 | Natural resources provided by nature, such as forests, minerals, water, and land itself. | Rent | 租金 |
| Labour | 劳动 | Human effort, both physical and mental, used in production. | Wages/Salaries | 工资 |
| Capital | 资本 | Man-made goods used to produce other goods, such as machinery, factories, and tools. | Interest | 利息 |
| Enterprise | 企业精神 | The willingness and ability to combine the other factors and take risks to start a business. | Profit | 利润 |
3. Opportunity Cost | 机会成本
Opportunity cost is the next best alternative forgone when a choice is made. It is not about everything you give up, just the single most desirable alternative you could have chosen instead. Every decision made by consumers, businesses, or governments involves an opportunity cost.
机会成本是做出选择时所放弃的次优替代。它并不是你所放弃的一切，而是你原本可以选择的那个最重要的替代选项。消费者、企业或政府所做的每一个决策都涉及机会成本。
For example, if a student has two hours and chooses to study economics instead of playing football, the opportunity cost is the enjoyment and exercise lost from not playing football. Similarly, if a government spends money on building a new hospital, the opportunity cost might be a new school or road that could have been built instead. Understanding opportunity cost helps rational decision-making.
例如，如果一个学生有两小时并选择学习经济而不是踢足球，机会成本就是踢足球所带来的乐趣和锻炼的放弃。同样，如果政府花钱建造一座新医院，机会成本可能是一所本可建造的学校或一条道路。理解机会成本有助于理性决策。
4. Production Possibility Curve | 生产可能性曲线
A production possibility curve (PPC) is a diagram that shows the maximum combination of two goods an economy can produce with its existing resources and technology. It illustrates the concepts of scarcity, choice, and opportunity cost in a clear visual form. Points on the curve are efficient; points inside the curve show underutilisation of resources.
生产可能性曲线 (PPC) 是一个图表，显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。它直观地说明了稀缺性、选择和机会成本的概念。曲线上的点表示有效率；曲线内的点表示资源未被充分利用。
Movement along the PPC demonstrates opportunity cost: producing more of one good requires giving up some of the other. An outward shift of the entire curve represents economic growth, which can be caused by an increase in the quantity or quality of resources, or technological improvements. A PPC helps economists analyse trade-offs and the cost of choices.
沿 PPC 的移动展示了机会成本：多生产一种商品需要放弃一定量的另一种商品。整条曲线向外移动代表经济增长，可能由资源数量或质量的提高或技术进步引起。PPC 帮助经济学家分析权衡取舍和选择的成本。
5. Economic Systems | 经济体系
Different societies answer the three fundamental economic questions — what to produce, how to produce, and for whom to produce — in different ways. This gives rise to three main types of economic systems: market economy, planned (command) economy, and mixed economy. Each system allocates resources differently.
不同的社会以不同方式回答三个基本经济问题：生产什么、如何生产、为谁生产。这就形成了三种主要的经济体系类型：市场经济、计划（指令）经济和混合经济。每种体系以不同的方式分配资源。
Market economy: Decisions are made by private individuals and firms through the price mechanism. There is little government intervention. Consumers' preferences and producers' profit motives guide resource allocation. | 市场经济：决策由私人个体和企业通过价格机制做出，政府干预很少。消费者偏好和生产者的利润动机引导资源配置。
Planned economy: The government owns most resources and controls production decisions. Central planning authorities decide what and how much to produce. | 计划经济：政府拥有大部分资源并控制生产决策。中央计划机构决定生产什么和生产多少。
Mixed economy: Combines elements of both market and planned systems. Most modern economies are mixed, with the private sector providing most goods and services while the government intervenes to correct market failures and provide public goods. | 混合经济：结合了市场与计划两种体系的要素。大多数现代经济体都是混合经济，私营部门提供大部分商品和服务，政府则干预以纠正市场失灵并提供公共物品。
6. Demand and Its Determinants | 需求及其决定因素
Demand refers to the willingness and ability of consumers to purchase a good or service at various prices over a given period of time. The law of demand states that, ceteris paribus (other things being equal), as the price of a good rises, the quantity demanded falls, and vice versa. This inverse relationship creates a downward-sloping demand curve.
需求是指消费者在一段时期内，在不同价格水平下愿意并能够购买某种商品或服务的数量。需求定律指出，在其他条件不变的情况下，商品价格上升时需求量下降，价格下降时需求量上升。这种反向关系形成了一条向下倾斜的需求曲线。
Several factors can shift the entire demand curve, not just movement along it. These determinants include changes in income, tastes and preferences, the price of related goods (substitutes and complements), expectations of future prices, and the number of buyers. For example, an increase in income usually shifts the demand for normal goods to the right, while a rise in the price of a substitute (like tea for coffee) will increase demand for the original good.
有几个因素可以导致整条需求曲线移动，而不仅仅是沿曲线移动。这些决定因素包括收入变化、偏好和口味、相关商品（替代品和互补品）的价格、对未来价格的预期以及买家的数量。例如，收入增加通常会使正常商品的需求向右移动，而替代品（如茶相对于咖啡）的价格上升会增加对原有商品的需求。
7. Supply and Its Determinants | 供给及其决定因素
Supply is the quantity of a good or service that producers are willing and able to offer for sale at various prices over a given time period. The law of supply states that, ceteris paribus, as price rises, the quantity supplied increases, producing an upward-sloping supply curve. This positive relationship reflects the profit incentive for producers.
供给是指生产者在特定时期内，在不同价格水平下愿意并能够提供销售的商品或服务的数量。供给定律指出，在其他条件不变的情况下，价格上升时供给量增加，形成向上倾斜的供给曲线。这种正向关系反映了利润对生产者的激励作用。
Shifts in the supply curve occur when something other than the price of the good changes. Key determinants include changes in the costs of production (wages, raw materials), technology improvements, taxes and subsidies, the number of sellers, and expectations. For instance, a government subsidy can lower production costs and shift the supply curve to the right, increasing supply at each price level.
当商品本身价格以外的因素发生变化时，供给曲线会发生移动。主要决定因素包括生产成本的变化（工资、原材料）、技术进步、税收和补贴、卖者的数量以及预期。例如，政府补贴可以降低生产成本，使供给曲线向右移动，在每个价格水平上增加供给量。
8. Market Equilibrium | 市场均衡
Market equilibrium occurs at the price where the quantity demanded by consumers equals the quantity supplied by producers. At this point, the market is in balance and there is no tendency for price to change. The equilibrium price is also called the market-clearing price because all goods supplied are bought.
市场均衡发生在消费者需求的数量等于生产者供给的数量的价格上。此时市场处于平衡状态，价格没有变动的趋势。均衡价格也称为市场出清价格，因为所有供给的商品都被购买。
If the price is set above equilibrium, there will be excess supply (a surplus), and producers may lower prices to sell their goods. If the price is below equilibrium, excess demand (a shortage) occurs, and consumers may bid prices up. The invisible hand of the market guides prices toward equilibrium. Changes in demand or supply will shift the curves, leading to a new equilibrium price and quantity.
如果价格定在均衡之上，就会出现超额供给（过剩），生产者可能降低价格以出售商品。如果价格低于均衡，就会出现超额需求（短缺），消费者可能会竞相抬价。市场的无形之手引导价格趋向均衡。需求或供给的变化会使曲线移动，导致新的均衡价格和均衡数量。
9. Price Elasticity of Demand (Introduction) | 需求价格弹性简介
Price elasticity of demand (PED) measures how responsive the quantity demanded is to a change in price. It is calculated as:
PED = (% Change in Quantity Demanded) ÷ (% Change in Price)
. A good is price elastic if the absolute value of PED is greater than 1, and price inelastic if less than 1.需求价格弹性 (PED) 衡量需求量对价格变化的反应程度。计算公式为：
PED = (需求量变动百分比) ÷ (价格变动百分比)
。当 PED 的绝对值大于 1 时，商品富有价格弹性；小于 1 时则缺乏弹性。Goods with many close substitutes, luxuries, and items that take a large share of income tend to have elastic demand. Necessities, addictive goods, and those with few substitutes tend to be inelastic. Understanding PED helps firms set prices to maximise total revenue, and governments predict tax revenues when imposing indirect taxes. A basic awareness of elasticity is essential even at Year 9 level.
拥有许多相近替代品、奢侈品以及占收入比重较大的商品，其需求往往富有弹性。必需品、成瘾性商品以及替代品少的商品往往缺乏弹性。理解 PED 有助于企业制定价格以实现总收益最大化，也有助于政府预测征收间接税时的税收收入。即使在 Year 9 阶段，对弹性的基本认识也至关重要。
10. Money and Its Functions | 货币及其职能
Money is any asset that is widely accepted as a means of payment. Before money, societies used barter, which required a double coincidence of wants — both parties must want what the other has at the same time. Money solves this problem and performs four key functions.
货币是任何被普遍接受作为支付手段的资产。在有货币之前，社会使用物物交换，这需要“需求的双重巧合”——双方必须同时想要对方拥有的东西。货币解决了这个问题，并履行四项关键职能。
Medium of exchange: Money is used to buy and sell goods and services, avoiding the inefficiencies of barter. | 交换媒介：货币用于买卖商品和服务，避免了物物交换的低效率。
Store of value: Money can be saved and used later, retaining its purchasing power over time. | 价值储藏：货币可以被储存并在以后使用，能够在一段时间内保持其购买力。
Unit of account: Money provides a common measure to value goods and services, making price comparisons possible. | 计价单位：货币提供了衡量商品与服务价值的通用尺度，使价格比较成为可能。
Standard of deferred payment: Money allows debts and future payments to be stated and settled. | 延期支付标准：货币允许以共同尺度计量和清偿债务及未来的付款。
These functions rely on trust and stability; if inflation is high, money can lose its value and some functions may weaken. Year 9 students should be comfortable explaining each function and comparing money with barter.
这些职能依赖于信任与稳定；如果通胀高企，货币就会贬值，某些职能可能会削弱。Year 9 学生应能熟练解释每一种职能，并对货币与物物交换进行比较。
Published by TutorHao | Economics Revision Series | aleveler.com
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