📚 GCSE Economics: Common Mistake Questions Explained | GCSE 经济：易错题精讲
Mastering GCSE Economics requires more than just memorising definitions – you need to think like an economist. Many students lose marks not because they do not know the content, but because they fall into predictable traps set by examiners. This article walks you through eight classic mistake-prone questions that appear year after year. For each one, we highlight the common error and the correct reasoning, helping you spot similar pitfalls in your own exams.
掌握 GCSE 经济不仅需要记忆定义，更需要像经济学家一样思考。很多学生丢分并非因为不了解内容，而是因为他们掉进了考官设置的可预测陷阱。本文为你梳理了每年都会出现的八道经典易错题，逐一指出常见错误和正确推理，帮你识别考试中类似的陷阱。
1. Demand vs Quantity Demanded | 需求与需求量的区别
Question: “The price of cinema tickets falls from £10 to £8. As a result, the number of tickets sold increases from 200 to 260. Does this represent an increase in demand, or an increase in the quantity demanded?”
问题：“电影票价格从 10 英镑降至 8 英镑，结果售票数量从 200 张增加到 260 张。这代表需求增加了，还是需求量增加了？”
Common mistake: Many students tick “increase in demand” because more tickets are being bought. They confuse a price-driven movement with a shift of the entire demand curve.
常见错误：许多学生打勾“需求增加”，因为买了更多的票。他们混淆了价格引起的移动和整条需求曲线的平移。
Correct reasoning: In standard demand theory, a change in the good’s own price causes a movement along the existing demand curve – a change in quantity demanded. Only changes in non-price determinants (such as income, tastes, or the price of substitutes) shift the entire demand curve left or right. Here, the price change alone explains the extra ticket sales, so the correct answer is “increase in quantity demanded.” Always check whether the change is triggered by price or by something else.
正确推理：在标准需求理论中，商品自身价格的变化导致沿原有需求曲线的移动——即需求量的变化。只有非价格决定因素（如收入、偏好或替代品价格）的变化才会使整条需求曲线向左或向右移动。本题中，单独的票价变化就能解释额外的售票量，因此正确答案是“需求量增加”。始终检查变化是由价格还是其他因素引起。
2. PED Calculation and Sign | 需求价格弹性计算与正负号
Question: “When the price of a chocolate bar rises from 50p to 55p, the quantity demanded falls from 1000 units per day to 850 units. Calculate the price elasticity of demand (PED) using the percentage-change method and state whether demand is elastic or inelastic.”
问题：“当巧克力棒价格从 50 便士上涨到 55 便士时，每日需求量从 1000 单位下降到 850 单位。使用百分比变化法计算需求价格弹性（PED），并说明需求是富有弹性还是缺乏弹性。”
Common mistake: Students often give the PED as a positive number, e.g. 1.5, by ignoring the negative sign or by inverting the formula. Another error is using the wrong base for percentage change – e.g. calculating 15% ÷ 10% = 1.5, which actually is 0.15 ÷ 0.10 = 1.5, but then mislabelling it.
常见错误：学生往往给出正数的 PED，例如 1.5，原因是忽略了负号或颠倒了公式。另一个错误是百分比变化用了错误的基数——例如计算为 15% ÷ 10% = 1.5，但标错了性质。
Correct calculation: %∆Qd = ((850 – 1000) ÷ 1000) × 100 = -15%. %∆P = ((55 – 50) ÷ 50) × 100 = 10%. PED = %∆Qd ÷ %∆P = -15% ÷ 10% = -1.5. We ignore the minus sign when classifying elasticity, so PED = 1.5. Since 1.5 > 1, demand is price elastic. Remember: PED for normal goods is always negative because of the law of demand, but we refer to its absolute value when saying “elastic” or “inelastic.” Never call it -1.5 elastic – the negative just reflects the inverse relationship.
正确计算：需求量变动百分比 = ((850 − 1000) ÷ 1000) × 100 = −15%。价格变动百分比 = ((55 − 50) ÷ 50) × 100 = 10%。PED = −15% ÷ 10% = −1.5。在判断弹性类型时我们忽略负号，所以 PED = 1.5。由于 1.5 > 1，需求富有价格弹性。记住：正常商品的需求价格弹性总是负值，因为需求定律，但我们说“富有弹性”或“缺乏弹性”时指的是绝对值。绝不要说 −1.5 富有弹性——负号只反映反向关系。
3. Shifts in Supply vs Movements | 供给曲线的移动与沿曲线移动
Question: “A technological improvement reduces the cost of producing smartphones. How does this affect the supply curve?”
问题：“技术进步降低了智能手机的生产成本。这如何影响供给曲线？”
Common mistake: A student might answer that there is a movement down the supply curve because the lower cost would lead to a lower price, which then increases quantity supplied. This mixes up cause and effect.
常见错误：学生可能回答供给曲线向下移动，因为成本降低会导致价格下降，进而供应量增加。这混淆了因果关系。
Correct reasoning: A reduction in costs of production is a non-price determinant of supply. It makes production more profitable at every given price, shifting the entire supply curve to the right (increase in supply). A movement along the supply curve can only be caused by a change in the good’s own price. The new technology does not initially change the good’s price; rather, the rightward shift of supply eventually pushes the market price down and raises equilibrium quantity. So the immediate effect is a shift, not a movement.
正确推理：生产成本下降是供给的非价格决定因素。它使任何给定价格下的生产更有利可图，将整条供给曲线向右移动（供给增加）。沿供给曲线的移动只能由商品自身价格的变化引起。新技术起初并不改变商品价格；相反，供给曲线右移最终会使市场价格下降并提高均衡数量。所以直接效应是平移，而非移动。
4. Tax Burden and Elasticity | 税收负担与弹性
Question: “The government imposes a specific tax of £1 per unit on a product. Demand for the product is perfectly inelastic. Who bears the entire tax burden?”
问题：“政府对某产品每单位征收 1 英镑的从量税。该产品的需求完全无弹性。谁承担全部税收负担？”
Common mistake: Many students argue that the producer and the consumer share the tax, because that is what happens in most textbook diagrams. They ignore the extreme elasticity case.
常见错误：很多学生认为生产者和消费者分摊税收，因为多数课本图示如此。他们忽略了极端弹性的情况。
Correct analysis: When demand is perfectly inelastic (vertical demand curve), quantity demanded does not respond to price changes. Producers can pass the entire tax on to consumers by raising the price by the full amount of the tax (£1). Consumers pay all of the tax; producers’ revenue net of tax remains unchanged. The burden falls 100% on consumers. Conversely, if supply were perfectly inelastic, the producer would bear all the tax. Always check elasticity to determine tax incidence.
正确分析：当需求完全无弹性（垂直的需求曲线），需求量对价格变化无反应。生产者可以通过将价格全额提高税额（1 英镑）将全部税收转嫁给消费者。消费者承担全部税收；生产者税后收入不变。税收负担 100% 落在消费者身上。相反，如果供给完全无弹性，生产者将承担全部税收。始终检查弹性以确定税负归宿。
5. Positive Externalities and Underproduction | 正外部性与供给不足
Question: “Education is said to generate positive externalities. Draw and explain why a free market is likely to under-provide education.”
问题：“教育被认为会产生正外部性。画图并解释为什么自由市场很可能提供不足的教育。”
Common mistake: Students often draw a diagram showing marginal social benefit (MSB) above marginal private benefit (MPB) but then incorrectly label the market equilibrium as being at the intersection of MSB and MPC. They may also say “the market provides too much education” due to confusion with negative externalities.
常见错误：学生常画出边际社会收益（MSB）高于边际私人收益（MPB）的图形，但随后错误地将市场均衡标在 MSB 与 MPC 的交点。他们也可能因为与负外部性混淆而说“市场提供了太多教育”。
Correct approach: In the presence of a positive externality in consumption, the MSB curve lies above the MPB curve. The free market operates where MPB = MPC, yielding a quantity Qmarket. The socially optimal quantity Qoptimum is found at MSB = MSC, which is greater. Because individuals only consider their own private benefit, they consume less than the socially desirable amount → underproduction. The diagram should show Qmarket left of Qoptimum. To correct this, governments can subsidise education, shifting the MPB curve upward or reducing the cost faced by consumers, moving quantity closer to the social optimum.
正确方法：当消费存在正外部性时，MSB 曲线位于 MPB 曲线的上方。自由市场在 MPB = MPC 处运行，得到数量 Q市场。社会最优数量 Q最优 在 MSB = MSC 处，该数量更大。因为个人仅考虑自身私人收益，他们消费的数量低于社会合意水平→供给不足。图形应显示 Q市场 位于 Q最优 的左侧。为纠正这一问题，政府可以对教育进行补贴，使 MPB 曲线上移或降低消费者面对的成本，从而使数量趋近社会最优。
6. PPF and Unemployment | 生产可能性边界与失业
Question: “An economy is experiencing high unemployment. What happens to the country’s PPF?”
问题：“某经济正经历高失业率。该国的 PPF 会发生什么变化？”
Common mistake: Students frequently say the PPF shifts outward because more labour becomes available, or shifts inward because potential output falls. They confuse movements towards/on the frontier with a shift of the frontier itself.
常见错误：学生常说 PPF 向外平移，因为可用的劳动力增多了；或者说 PPF 向内平移，因为潜在产出下降了。他们混淆了向边界/在边界上的移动与边界本身的平移。
Correct reasoning: The PPF shows the maximum possible output combinations when all resources are fully and efficiently employed. If there is unemployment, the economy is producing at a point inside the PPF – not on the frontier. Reducing unemployment allows the economy to move from a point inside the PPF to a point closer to or on the PPF, but the PPF itself does not shift. The curve only shifts outward if there is an increase in the quantity or quality of resources, or improvements in technology, not simply because idle resources are brought into use. Make sure you can distinguish “actual output” from “potential output.”
正确推理：PPF 表示在全部资源被充分且有效率地利用时可实现的最大产出组合。如果存在失业，经济在生产可能性边界内的某点运行——不在边界上。减少失业可使经济从边界内的点移动到更接近或正处于边界上的点，但 PPF 本身并不移动。只有在资源数量或质量增加或技术进步时，曲线才会向外平移，而不是仅仅因为闲置资源被投入使用。务必区分“实际产出”与“潜在产出”。
7. Monetary vs Fiscal Policy Instruments | 货币政策与财政政策工具
Question: “The central bank wants to reduce inflationary pressure. Which of the following is a monetary policy measure it could use? (A) Increase income tax (B) Increase the base interest rate (C) Increase government spending (D) Reduce subsidies.”
问题：“中央银行想减轻通胀压力。以下哪项是它可以使用的货币政策措施？(A) 提高所得税 (B) 提高基准利率 (C) 增加政府支出 (D) 削减补贴。”
Common mistake: Many students select (A) or (C) because they know these are contractionary actions, but they forget that taxation and government spending are fiscal policy tools controlled by the government, not the central bank. The central bank uses monetary policy – changing the interest rate, money supply, or quantitative easing.
常见错误：许多学生选择 (A) 或 (C)，因为他们知道这些是紧缩性行动，但忘了税收和政府支出是由政府控制的财政政策工具，而非中央银行。中央银行使用货币政策——改变利率、货币供应量或量化宽松。
Correct analysis: The central bank can raise the base interest rate (option B). A higher interest rate increases the cost of borrowing and the reward for saving, which tends to reduce consumption and investment – two components of aggregate demand. This dampens inflationary pressure. Income tax changes and government spending adjustments (A and C) are fiscal policy, under the control of the Treasury. Subsidies (D) are also a fiscal measure. So B is the only correct monetary policy tool listed.
正确分析：中央银行可以提高基准利率（选项 B）。较高的利率增加借贷成本和储蓄回报，倾向于减少消费和投资——总需求的两个组成部分。这会抑制通胀压力。所得税变动和政府支出调整（A 和 C）是财政政策，由财政部控制。补贴（D）也属于财政措施。因此 B 是所列中唯一的货币政策工具。
8. Types of Unemployment Explained | 失业类型的辨析
Question: “A car factory replaces most of its assembly-line workers with robots. The displaced workers find it difficult to get new jobs because they lack the digital skills needed in other manufacturing sectors. Which type of unemployment best describes their situation?”
问题：“一家汽车工厂用机器人替代了大部分流水线工人。这些被替代的工人难以找到新工作，因为他们缺乏其他制造业所需的数字技能。哪种失业类型最能描述他们的状况？”
Common mistake: Students often label this as cyclical unemployment because it occurred during factory restructuring, or think it is frictional because the workers are “between jobs.” This reveals confusion between structural and frictional unemployment.
常见错误：学生常把此标为周期性失业，因为它发生在工厂重组期间；或认为是摩擦性失业，因为这些工人“在换工作期间”。这暴露了结构性失业和摩擦性失业之间的混淆。
Correct classification: This is structural unemployment – a mismatch between the skills workers have and the skills employers require, often caused by technological change or changes in the pattern of what goods are produced. Frictional unemployment is short-term and occurs when people are moving between jobs, often with the right skills for available vacancies; it is usually voluntary. Cyclical unemployment is linked to the business cycle – a lack of aggregate demand during a recession. The robots scenario is a classic case of technological structural unemployment, which often requires retraining programmes to resolve.
正确分类：这是结构性失业——工人拥有的技能与雇主要求的技能不匹配，通常由技术变革或产品生产模式的变化引起。摩擦性失业是短期的，发生在人们在换工作期间，他们通常具备适合空缺职位的技能；通常是自愿的。周期性失业与经济周期相关——衰退期间总需求不足。机器人情景是典型的技术性结构性失业，通常需要再培训项目来解决。
Published by TutorHao | Economics Revision Series | aleveler.com
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