Year 13 CIE Economics: Essential Content Review | Year 13 CIE 经济：核心知识点梳理

📚 Year 13 CIE Economics: Essential Content Review | Year 13 CIE 经济：核心知识点梳理

This article provides a structured overview of the key A2 topics covered in the Cambridge International (CIE) Year 13 Economics syllabus. It highlights the essential microeconomic and macroeconomic concepts, models, and policies that students must master for examination success. Each section is designed to reinforce understanding and connect theory to real-world applications.

本文系统梳理了剑桥国际（CIE）A2（Year 13）经济学的核心知识点，涵盖微观与宏观的核心概念、模型与政策工具。每一部分旨在帮助学生巩固理论框架，并将抽象模型与真实经济现象联系起来，为考试复习提供清晰路线图。

1. Efficiency and Market Failure | 效率与市场失灵

Economic efficiency is central to resource allocation. Allocative efficiency occurs when price equals marginal cost (P = MC), ensuring resources follow consumer demand. Productive efficiency exists when firms produce at the lowest point on the average cost curve (AC = MC), minimising waste. Dynamic efficiency arises from innovation and investment over time, improving products and processes.

经济效率是资源配置的核心。配置效率发生在价格等于边际成本（P = MC）时，确保资源追随消费者需求。生产效率指企业在平均成本曲线最低点生产（AC = MC），使浪费最小化。动态效率来自长期创新与投资，推动产品与工艺的升级。

Market failure occurs when the free market fails to achieve allocative efficiency. Key causes include externalities (negative production/consumption and positive production/consumption), public goods (non-rival and non-excludable) causing free-rider problems, imperfect information preventing informed choices, and market power distorting prices. Merit and demerit goods further highlight information failures where social optimum diverges from private equilibrium.

市场失灵指自由市场无法实现配置效率。主要原因包括外部性（负生产/消费、正生产/消费），公共物品（非竞争性、非排他性）引发的搭便车问题，信息不对称导致选择偏差，以及市场势力扭曲价格。优值品与劣值品进一步揭示因信息失灵导致社会最优与私人均衡的偏离。

Deadweight welfare loss quantifies the efficiency loss from market failure. External costs shift marginal social cost (MSC) above marginal private cost (MPC), causing overproduction; external benefits shift marginal social benefit (MSB) above marginal private benefit (MPB), causing underproduction. Government intervention aims to internalise these externalities.

无谓福利损失衡量市场失灵的效率损失。外部成本使边际社会成本（MSC）高于边际私人成本（MPC），导致过度生产；外部收益使边际社会收益（MSB）高于边际私人收益（MPB），导致生产不足。政府干预旨在将这些外部性内部化。

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2. Consumer Choice Theory: Utility, Indifference Curves and Budget Lines | 消费者选择理论：效用、无差异曲线与预算线

The law of diminishing marginal utility states that as consumption of a good increases, the additional utility from each extra unit falls. A rational consumer maximises total utility where the marginal utility per currency unit spent is equal across all goods: MUₓ/Pₓ = MUᵧ/Pᵧ. This is the equi-marginal principle.

边际效用递减规律指出，随着对某种商品消费量的增加，每额外一单位带来的效用增量下降。理性消费者在每种商品上每单位货币支出的边际效用相等时实现总效用最大化：MUₓ/Pₓ = MUᵧ/Pᵧ。这就是等边际原理。

An indifference curve shows combinations of two goods that yield the same total utility. Curves are downward sloping, convex to the origin (diminishing marginal rate of substitution, MRS), and never intersect. Higher curves represent higher utility. A budget line depicts all combinations attainable given income and prices Px and Py.

无差异曲线表示能给消费者带来相同总效用的两种商品组合。曲线向下倾斜、凸向原点（边际替代率递减），且永不相交。越高的无差异曲线代表越高的效用水平。预算线表示在既定收入与价格Px和Py下能够购买的所有商品组合。

Consumer equilibrium is achieved at the point where the budget line is tangent to the highest attainable indifference curve. Here, MRS = Px/Py, so the rate at which the consumer is willing to substitute equals the market exchange rate. Income and substitution effects decompose the impact of a price change: the substitution effect always leads to consuming more of the relatively cheaper good, while the income effect can be positive (normal goods) or negative (inferior goods), even leading to upward-sloping demand for Giffen goods.

消费者均衡位于预算线与最高可及无差异曲线的切点。此时 MRS = Px/Py，即消费者愿意替代的比率等于市场交换比率。价格变化的影响分解为收入效应与替代效应：替代效应总使消费者多消费相对便宜的商品，而收入效应对于正常品为正，对于低档品为负，甚至使得吉芬商品的需求曲线呈正斜率。

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3. Costs, Revenues and Profit | 成本、收益与利润

In the short run, at least one factor is fixed. Total cost (TC) = total fixed cost (TFC) + total variable cost (TVC). Average cost (ATC) falls initially due to increasing returns, then rises as diminishing returns set in. Marginal cost (MC) intersects ATC at its minimum point. The short-run cost curves are U-shaped.

在短期，至少一种生产要素固定。总成本（TC）= 总固定成本（TFC）+ 总可变成本（TVC）。平均成本（ATC）因报酬递增先下降，而后随着报酬递减上升，边际成本（MC）穿过ATC的最低点。短期成本曲线呈U形。

In the long run, all factors are variable. Economies of scale reduce long-run average cost (LRAC) as output expands, due to technical, managerial, financial, marketing and risk-bearing factors. Diseconomies of scale eventually push LRAC upward, creating an L-shaped or U-shaped LRAC curve. Minimum efficient scale (MES) identifies the output level where all economies of scale are exhausted.

在长期，所有生产要素可变。规模经济随着产量扩大降低长期平均成本（LRAC），原因包括技术、管理、金融、营销和风险分担等。规模不经济最终推高LRAC，形成L形或U形LRAC曲线。最小有效规模（MES）指所有规模经济被耗尽时的产出水平。

Revenue concepts: total revenue (TR), average revenue (AR = demand), and marginal revenue (MR). In perfect competition, AR = MR and the firm is a price taker. In imperfect competition, the firm faces a downward-sloping AR curve, so MR lies below AR. Profit maximisation occurs where MR = MC. Normal profit (zero economic profit) is earned when AR = ATC; supernormal profit when AR > ATC.

收益概念：总收益（TR）、平均收益（AR=需求）与边际收益（MR）。在完全竞争下，AR=MR，企业是价格接受者。在不完全竞争下，企业面临向下倾斜的AR曲线，因此MR低于AR。利润最大化发生在MR=MC处。当AR=ATC时获得正常利润（零经济利润）；当AR>ATC时获得超额利润。

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4. Market Structures | 市场结构

Perfect competition is characterised by many small firms, homogeneous products, free entry and exit, and perfect information. In the long run, firms earn normal profit because any supernormal profit attracts new entrants, shifting supply right until P = AR = MR = MC = ATC. This achieves both allocative and productive efficiency, maximising consumer welfare.

完全竞争的特征包括大量小企业、同质产品、自由进出和完全信息。长期中企业仅获得正常利润，因为任何超额利润都会吸引新进入者，使供给右移直至 P=AR=MR=MC=ATC。这同时实现了配置效率与生产效率，消费者福利最大化。

Monopoly exists when a single firm dominates the market with high barriers to entry. The monopolist restricts output and charges a price above MC (P > MC), causing allocative inefficiency and deadweight loss. It may also suffer from X-inefficiency and lack of innovation, although potential benefits include economies of scale and dynamic efficiency through reinvested supernormal profit.

垄断指单一企业主导市场且存在高进入壁垒。垄断者限制产量并制定高于边际成本的价格（P > MC），导致配置无效率与无谓损失。垄断还可能带来X-非效率与创新动力不足，但潜在好处包括规模经济以及利用超额利润再投资实现的动态效率。

Monopolistic competition combines many firms with differentiated products and low barriers. In the short run, firms can earn supernormal profit; in the long run, new entrants shift demand left until AR is tangent to ATC, giving normal profit. While not productively or allocatively efficient, the variety of choice can be a source of consumer benefit.

垄断竞争兼具众多企业与产品差异化、低壁垒的特点。短期内企业可获得超额利润；长期中新进入者使需求左移，直至AR与ATC相切，仅获正常利润。该结构虽未达到生产效率与配置效率，但消费者可享受多样化选择的好处。

Oligopoly is dominated by a few interdependent firms. The kinked demand curve model explains price rigidity: if a firm raises price, rivals do not follow (elastic above kink); if it lowers price, rivals match (inelastic below kink). This creates a discontinuous MR curve, meaning MC changes within the vertical gap do not alter the profit-maximising price. Game theory, including the prisoner’s dilemma, explains collusive and non-collusive behaviour.

寡头垄断由少数相互依存的企业主导。弯折需求曲线模型解释了价格刚性：若企业提价，对手不跟进，此时需求弹性大；若企业降价，对手跟进，需求缺乏弹性。这导致MR曲线出现垂直间断，意味着MC在该间断内变化不影响利润最大化价格。博弈论（如囚徒困境）可用于解释合谋与非合谋行为。

Contestable markets experience the threat of entry that disciplines incumbents, even with few firms. Conditions include no sunk costs, free entry and exit, and the ability of entrants to ‘hit and run’. The market may deliver competitive outcomes (P = AC) without atomistic competition.

可竞争市场中，即便厂商数量少，潜在进入威胁也能约束在位企业。条件包括无沉没成本、自由进出以及进入者“打了就跑”的能力。此类市场可在没有原子式竞争的情况下达到竞争性结果（P=AC）。

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5. Firms’ Growth and Objectives | 企业成长与目标

Firms grow internally through reinvestment and externally via mergers and acquisitions (M&A). Horizontal integration combines firms at the same stage of production; vertical integration connects different stages (backward/forward); conglomerate integration links unrelated businesses. Each brings potential synergies, economies of scale, or diversification advantages but may also cause diseconomies of scale or regulatory concerns.

企业通过再投资实现内部增长，或通过并购实现外部增长。横向一体化整合同一生产阶段的企业；纵向一体化连接不同阶段（后向/前向）；混合兼并则结合不相关业务。各方式都可带来协同效应、规模经济或多元化优势，但也可能引发规模不经济或监管关注。

Traditional theory assumes profit maximisation (MR = MC). However, the principal-agent problem (separation of ownership and control) leads to alternative objectives: sales revenue maximisation (MR = 0) to increase market share, growth maximisation, satisficing (achieving satisfactory profits) under bounded rationality, and corporate social responsibility (CSR) influences. Such behavioural theories better explain observed firm strategies.

传统理论假定企业追求利润最大化（MR=MC）。但委托–代理问题（所有权与控制权分离）催生了多种目标：销售收入最大化（MR=0）以扩大市场份额、增长最大化、有限理性下的满意化，以及企业社会责任（CSR）的影响。这些行为理论更好地解释了现实中的企业策略。

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6. Government Microeconomic Intervention | 政府微观经济干预

To correct negative externalities of production, governments can impose indirect taxes (e.g., carbon tax) to shift MPC upward toward MSC, reducing output to the socially optimal level. For negative consumption externalities, an ad valorem or specific tax raises the price consumers face, internalising the external cost. Subsidies work oppositely for positive externalities, lowering marginal private cost or raising marginal private benefit.

为纠正生产的负外部性，政府可征收间接税（如碳税），将MPC曲线上推至MSC，使产量降至社会最优水平。针对消费负外部性，从价税或从量税提高消费者面对的价格，从而内部化外部成本。补贴则相反，对正外部性降低边际私人成本或提高边际私人收益。

Tradable pollution permits create a market for emissions, capping total pollution. Firms with low abatement costs sell permits to those with high costs, achieving the total pollution target at the lowest overall cost. This combines regulatory certainty with market flexibility, as seen in emission trading schemes.

可交易排污许可证为排放创造了一个市场，设定总污染上限。低减排成本企业可将许可证出售给高成本企业，以最低总成本实现污染总量目标。这种机制兼顾监管确定性与市场灵活性，例如碳排放交易体系。

Information failures can be addressed through compulsory labelling, quality standards, and public education campaigns. For public goods, direct state provision funded by taxation can overcome the free-rider problem. Price controls (maximum price below equilibrium to protect consumers, minimum price above equilibrium to support producers or wages) distort markets, causing shortages or surpluses, and require careful evaluation of side effects.

信息失灵可通过强制标签、质量标准和公众教育来解决。对于公共物品，国家以税收资金直接提供可克服搭便车问题。价格管制（低于均衡的最高限价保护消费者，高于均衡的最低限价支持生产者或工资）会扭曲市场，造成短缺或过剩，需要谨慎评估副作用。

Labour market intervention, such as a national minimum wage above the market-clearing level, can cause classical unemployment if set too high, but a moderate floor may boost productivity (efficiency wage theory) and reduce poverty without significant job losses. Trade unions and improved worker rights also affect labour market outcomes.

劳动力市场干预，例如将全国最低工资设定于市场出清水平之上，若过高可能导致古典式失业，但适度的工资下限可能提高生产率（效率工资理论）并减少贫困而不会引起大量失业。工会与工人权益改善也会影响劳动力市场结果。

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7. Aggregate Demand and Aggregate Supply | 总需求与总供给

Aggregate demand (AD) compiles consumption (C), investment (I), government spending (G), and net exports (X – M). The AD curve slopes downward due to the real balance effect, interest rate effect (Keynes), and net export effect. Shifts in AD result from changes in its components or via fiscal and monetary policy.

总需求（AD）由消费（C）、投资（I）、政府支出（G）和净出口（X-M）组成。AD曲线因实际余额效应、利率效应（凯恩斯）和净出口效应而向下倾斜。AD的移动源于其组成部分变化或财政与货币政策的影响。

The short-run aggregate supply (SRAS) curve slopes upward because some input prices (especially wages) are sticky, so a higher price level raises profit margins and output. SRAS can shift due to changes in raw material costs, energy prices, indirect taxes, or supply shocks. Long-run aggregate supply (LRAS) is vertical in the classical model at the full-employment level of output, reflecting the economy’s potential output determined by factor quantity, quality, and technology. In the Keynesian model, LRAS is horizontal at low output levels (spare capacity) and becomes vertical only at full capacity.

短期总供给（SRAS）曲线向上倾斜，因为某些投入品价格（尤其是工资）具有粘性，较高的价格水平会提高利润率与产出。SRAS可因原材料成本、能源价格、间接税或供给冲击而移动。在古典模型中，长期总供给（LRAS）在充分就业产出水平呈垂直线，反映由要素数量、质量和技术决定的潜在产出。在凯恩斯模型中，LRAS在低产出阶段呈水平（存在闲置产能），仅在达到满负荷时才变为垂直。

Macroeconomic equilibrium occurs where AD = SRAS. A positive AD shock raises real GDP and the price level, potentially creating an inflationary gap. A negative supply shock shifts SRAS left, causing stagflation (falling output and rising price level). The multiplier effect means an initial change in spending (e.g., investment) leads to a larger final change in national income: multiplier = 1/(1 – MPC) or 1/(MPS + MPT + MPM) in an open economy with government.

宏观经济均衡发生于AD=SRAS处。正向AD冲击提高实际GDP和价格水平，可能产生通胀缺口。负面供给冲击使SRAS左移，导致滞胀（产出下降而物价上升）。乘数效应意味着初始支出变化（如投资）会引起国民收入的更大最终变化：在含政府的开放经济中，乘数=1/(1-MPC) 或 1/(MPS+MPT+MPM)。

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8. Macroeconomic Objectives and Policies | 宏观经济目标与政策

Governments typically pursue four main objectives: sustainable economic growth, low and stable inflation (CPI usually 2%), low unemployment (at the natural rate or NAIRU), and a satisfactory balance of payments position. They may also target equitable income distribution and environmental sustainability.

政府通常追求四大目标：可持续的经济增长、低而稳定的通胀（如CPI 2%目标）、低失业率（自然失业率或NAIRU），以及满意的国际收支状况。此外还可能包括收入公平分配与环境可持续性。

Fiscal policy involves changes in government spending and taxation. Expansionary fiscal policy (increased G or lower taxes) boosts AD and can close a deflationary gap, but may raise budget deficit and national debt. Contractionary fiscal policy cools an overheated economy. Automatic stabilisers (progressive taxes, welfare payments) help smooth the business cycle without discretionary action.

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或减税）刺激AD，可弥合通缩缺口，但可能提高财政赤字与国债。紧缩性财政政策则为过热的经济降温。自动稳定器（累进税制、福利支出）无需相机抉择即可熨平经济周期。

Monetary policy, operated by the central bank, manipulates the interest rate, money supply, or exchange rate to influence AD. Lower interest rates reduce the cost of borrowing, stimulate consumption and investment, and often weaken the exchange rate, improving net exports. Quantitative easing (QE) injects liquidity directly when interest rates approach the zero lower bound. Tight monetary policy raises rates to curb inflation.

货币政策由中央银行执行，通过调节利率、货币供给或汇率影响AD。降低利率减少借贷成本，刺激消费与投资，并通常使汇率贬值，改善净出口。当利率接近零下限时，量化宽松（QE）直接注入流动性。紧缩性货币政策则提高利率以遏制通胀。

Supply-side policies aim to increase the economy’s productive capacity (shift LRAS right). Market-based measures include privatization, deregulation, lower income/corporation taxes to incentivise work and investment. Interventionist measures involve education and training, infrastructure spending, and support for R&D. Successful supply-side policies can achieve non-inflationary growth and reduce structural unemployment.

供给侧政策旨在提升经济的生产能力（使LRAS右移）。市场化措施包括私有化、放松管制、降低所得税/公司税以激励工作与投资。干预主义措施包括教育培训、基础设施支出和研发支持。成功的供给侧政策可实现无通胀增长并降低结构性失业。

Policy conflicts are common: expansionary fiscal policy may reduce unemployment but worsen inflation and the trade balance. High interest rates control inflation but may reduce growth and increase unemployment. The Phillips curve illustrates a short-run trade-off between inflation and unemployment, but in the long run, the curve is vertical at the natural rate, implying no permanent trade-off.

政策目标冲突十分常见：扩张性财政政策可能降低失业但加剧通胀与贸易逆差。高利率控制通胀却可能减少增长、增加失业。菲利普斯曲线显示了短期中通胀与失业的权衡取舍，但长期菲利普斯曲线在自然失业率处垂直，意味着不存在永久权衡。

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9. International Trade and Globalisation | 国际贸易与全球化

The law of comparative advantage states that countries benefit from specialisation and trade even if one has an absolute advantage in all goods, as long as they have different opportunity costs. Specialisation according to comparative advantage allows trading partners to consume beyond their production possibility frontiers (PPFs). Assumptions include perfect factor mobility domestically, no transport costs, and constant returns to scale.

比较优势法则表明，即使一国在所有商品上都具有绝对优势，只要两国机会成本不同，通过专业化分工与贸易仍可受益。按照比较优势进行专业化分工使贸易伙伴能够在生产可能性边界（PPF）之外进行消费。假设条件包括国内要素完全流动、无运输成本以及规模报酬不变。

Free trade brings advantages such as lower consumer prices, greater variety, economies of scale, technology transfer, and efficiency gains from competition. However, countries may impose protectionist measures: tariffs (tax on imports), quotas (quantity limits), subsidies to domestic producers, and non-tariff barriers (regulations). Protectionism shields infant industries, protects jobs, and may correct trade deficits, but it typically raises prices, reduces choice, and invites retaliation.

自由贸易带来诸多好处：降低消费品价格、增加种类、实现规模经济、促进技术转移以及通过竞争提升效率。但各国可能采取保护主义措施：关税（进口税）、配额（数量限制）、对国内生产者的补贴以及非关税壁垒（法规）。保护主义可保护幼稚产业或就业、纠正贸易逆差，但通常抬高价格、减少选择并可能引发报复。

Globalisation is the increasing integration of economies through trade, capital flows, migration, and technology diffusion. It boosts growth through dynamic efficiency but can increase income inequality within and between nations, cause structural unemployment, and worsen environmental pressures. Multinational corporations (MNCs) play a key role, bringing FDI and employment but may also exploit labour and engage in transfer pricing.

全球化是通过贸易、资本流动、移民与技术扩散实现经济体日益融合的过程。它通过动态效率促进增长，但也可能加剧国家内部及国家间的收入不平等，导致结构性失业并加剧环境压力。跨国公司（MNCs）扮演关键角色，带来外国直接投资和就业，但可能剥削劳动力并利用转移定价。

Trading blocs such as free trade areas, customs unions, and common markets promote regional integration. Trade creation occurs when high-cost domestic production is replaced by lower-cost imports from a member country; trade diversion happens when low-cost non-member suppliers are displaced by higher-cost member suppliers due to a common external tariff. The EU, USMCA, and ASEAN exemplify different depths of integration.

贸易集团如自由贸易区、关税同盟和共同市场促进区域一体化。贸易创造发生在高成本国内生产被成员国低成本进口取代时；贸易转移则指因共同对外关税，低成本非成员国供给被高成本成员国供给挤出。欧盟、美墨加协定和东盟体现了不同层次的一体化。

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10. Balance of Payments and Exchange Rates | 国际收支与汇率

The balance of payments records all transactions between a country and the rest of the world. The current account includes trade in goods, trade in services, primary income (investment income and compensation of employees), and secondary income (transfers). The capital and financial account records capital transfers and transactions in non-produced, non-financial assets, plus direct investment, portfolio investment, and reserve assets. The accounts must balance in an accounting sense, though imbalances in the current account are common.

国际收支记录了一国与世界其他国家/地区之间的全部经济交易。经常账户包括货物贸易、服务贸易、初次收入（投资收益和雇员报酬）和二次收入（转移支付）。资本与金融账户记录资本转移、非生产非金融资产交易，以及直接投资、证券投资和储备资产。在会计意义上账户必然平衡，但经常账户失衡十分常见。

A current account deficit indicates a country spends more on imports, investment income, and transfers than it earns. Causes include low competitiveness, strong domestic demand, an overvalued currency, and structural weaknesses. Deficits must be financed by a surplus on the capital and financial account, possibly leading to rising foreign debt. Long-run solutions require supply-side improvements or expenditure-switching policies (e.g., depreciation).

经常账户赤字反映一国在进口、投资收入与转移支付上的支出超过其收入。原因包括竞争力低下、国内需求旺盛、汇率高估以及结构性弱点。赤字必须由资本与金融账户顺差融资，可能导致外债累积。长期解决之道需要供给侧改革或支出转换政策（如货币贬值）。

Exchange rate systems: a free-floating rate is determined purely by market forces of demand and supply. Factors causing shifts include relative interest rates, inflation differentials, current account positions, speculation, and terms of trade changes. A fixed exchange rate is pegged by the central bank through direct intervention using foreign reserves or interest rate adjustments. A managed float combines market forces with occasional central bank smoothing.

汇率制度：自由浮动汇率由市场供求完全决定。导致汇率变动的因素包括相对利率、通胀差异、经常账户状况、投机活动和贸易条件变化。固定汇率由中央银行通过动用外汇储备或调整利率直接干预以钉住某一货币。管理浮动汇率则结合市场力量与央行的偶然平滑干预。

A depreciation (floating) or devaluation (fixed) makes exports cheaper and imports dearer, aiming to improve the current account. The Marshall-Lerner condition states that a depreciation improves the trade balance only if the sum of the price elasticities of demand for exports and imports is greater than 1 (|PEDx| + |PEDm| > 1). Even when this holds, the J-curve effect suggests the trade balance may worsen in the short run before improving, as contracts and adjustment lags take time.

浮动下的贬值或固定下的法定贬值使出口更便宜、进口更昂贵，旨在改善经常账户。马歇尔-勒纳条件指出，只有当出口需求价格弹性与进口需求价格弹性绝对值之和大于1（|PEDx|+|PEDm|>1）时，贬值才能改善贸易平衡。即便条件满足，J曲线效应表明贸易平衡短期内可能先恶化再改善，因为合同与调整存在时滞。

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Published by TutorHao | Economics Revision Series | aleveler.com

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