📚 AS WJEC Economics: Unit Test Mock Paper Analysis | AS WJEC 经济：单元测试模拟卷解析
This article provides a detailed walkthrough of a mock paper designed for the WJEC AS Economics Unit 1 (Introduction to Economic Principles). Each question is followed by a bilingual explanation that clarifies key concepts, typical mistakes, and exam technique. Use this analysis to reinforce your understanding of fundamental microeconomic and macroeconomic ideas, and to improve your performance on multiple‑choice and structured‑response items.
本文详细解析了一套针对 WJEC AS 经济单元一（经济学原理导论）设计的模拟试卷。每道题后附有中英双语的解析，阐明核心概念、常见错误和应试技巧。请利用本解析强化你对基础微观与宏观经济理念的理解，并提升在选择题和简答题上的表现。
1. Question 1 – The Basic Economic Problem | 第一题 – 基本经济问题
Which of the following best defines the basic economic problem?
以下哪一项最准确地定义了基本经济问题？
Answer: C – Limited resources and unlimited wants.
答案：C – 资源有限而欲望无限。
The fundamental issue studied in economics is scarcity: we have finite factors of production (land, labour, capital, enterprise) but infinite human desires for goods and services. This forces societies and individuals to make choices about what to produce, how to produce, and for whom to produce. Options A and B confuse the result of scarcity with its definition, while D overlooks the constraint side.
经济学研究的根本问题是稀缺性：生产要素（土地、劳动力、资本、企业家才能）是有限的，而人类对商品和服务的欲望是无限的。这迫使社会和个人在生产什么、如何生产和为谁生产上做出选择。选项 A 和 B 将稀缺性的后果与定义混淆，D 忽略了资源的约束。
2. Question 2 – Opportunity Cost | 第二题 – 机会成本
A student decides to spend one hour revising economics instead of working a part‑time job that pays £8 per hour. The opportunity cost of this decision is:
一名学生决定花一小时复习经济，而不是做一份时薪 8 英镑的兼职工作。该决策的机会成本是：
Answer: B – The £8 forgone and the next best use of that hour.
答案：B – 所放弃的 8 英镑以及该小时的下一个最佳用途。
Opportunity cost is the value of the next best alternative sacrificed. Here, the monetary component is £8, but the concept also captures any non‑monetary satisfaction lost from the part‑time job (experience, socialising). Therefore the cost is not just the money, but the entire benefit of the next best option. Option A ignores the full definition, and C only counts the £8 while missing the broader sacrifice.
机会成本是所放弃的次优选择的价值。此处金钱部分是 8 英镑，但该概念还包括兼职工作中失去的非货币满足感（经验、社交）。因此成本不仅是金钱，而是次优方案的全部收益。A 忽略了完整定义，C 只计算 8 英镑而遗漏了更广泛的牺牲。
3. Question 3 – Production Possibility Frontier | 第三题 – 生产可能性边界
A point inside a production possibility frontier (PPF) indicates:
生产可能性边界内的一点表示：
Answer: D – Resources are not being fully utilised.
答案：D – 资源未被充分利用。
The PPF shows the maximum possible output combinations of two goods given current resources and technology. Any point on the curve is productively efficient. A point inside means there is unemployment or inefficiency – the economy could produce more of one or both goods without any trade‑off. The other options describe points on or outside the PPF, not inside it.
生产可能性边界显示在现有资源和技术下两种商品的最大可能产出组合。曲线上的任何一点都代表生产效率。内部点意味着存在失业或低效率——经济体无需权衡便可生产更多一种或两种商品。其他选项描述的是曲线上或曲线外的点，而非内部点。
4. Question 4 – The Law of Demand | 第四题 – 需求定律
The law of demand states that, ceteris paribus, as the price of a good rises:
需求定律指出，在其他条件不变的情况下，当一种商品的价格上升时：
Answer: A – Quantity demanded falls.
答案：A – 需求量下降。
The law of demand reflects the inverse relationship between price and quantity demanded: consumers tend to buy less of a good when its price increases, because their real income falls (income effect) and they switch to relatively cheaper substitutes (substitution effect). It is a movement along the demand curve, not a shift of the curve. Options B and C imply a shift, while D contradicts the law.
需求定律反映了价格与需求量之间的反向关系：价格上升时消费者倾向于购买更少，因为实际收入下降（收入效应）且转向相对更便宜的替代品（替代效应）。这是沿着需求曲线的移动，而非曲线移动。B 和 C 暗示曲线移动，D 与定律相悖。
5. Question 5 – Determinants of Supply | 第五题 – 供给的决定因素
A fall in the cost of raw materials for manufacturing smartphones will most likely cause:
制造智能手机的原材料成本下降最有可能导致：
Answer: C – The supply curve to shift to the right.
答案：C – 供给曲线向右移动。
Lower input costs reduce firms’ production expenses, making it more profitable to supply any given quantity. This shifts the supply curve outward (to the right), meaning a larger quantity supplied at each price. It is a shift of the curve, not a movement along it, because the change is not caused by a price variation of the good itself. Option A would occur if the good’s own price rose, while B would imply higher costs.
原材料成本下降降低了企业的生产费用，使得供应任何给定数量更有利可图。这使供给曲线向外（向右）移动，意味着每个价格下供给量更大。这是曲线的移动而非沿曲线移动，因为变化并非由商品自身价格变动引起。若商品自身价格上升会出现 A，B 则暗示成本上升。
6. Question 6 – Price Elasticity of Demand | 第六题 – 需求价格弹性
A cinema reduces ticket prices from £10 to £8, and the number of tickets sold increases from 500 to 600 per week. Using the midpoint (arc) formula, the price elasticity of demand is approximately:
一家电影院将票价从 10 英镑降至 8 英镑，每周售票量从 500 张增加到 600 张。利用中点（弧）公式，需求价格弹性大约为：
Answer: C – –0.82 (or 0.82 in absolute terms).
答案：C – –0.82（绝对值 0.82）。
The midpoint formula is: PED = (ΔQ/Qₐᵥₑ) ÷ (ΔP/Pₐᵥₑ), where Qₐᵥₑ = (500+600)/2 = 550, ΔQ = +100; Pₐᵥₑ = (10+8)/2 = 9, ΔP = –2. Thus, PED = (100/550) ÷ (–2/9) ≈ 0.1818 / –0.2222 = – he total revenue fell: lower price did not boost quantity enough to offset the price drop.
中点公式为：PED = (ΔQ/Qₐᵥₑ) ÷ (ΔP/Pₐᵥₑ)， 其中 Qₐᵥₑ = (500+600)/2 = 550，ΔQ = +100；Pₐᵥₑ = (10+8)/2 = 9，ΔP = –2。 因此 PED = (100/550) ÷ (–2/9) ≈ 0.1818 / –0.2222 = –0.818。由于绝对值小于 1，需求缺乏弹性。这解释了为何总收入下降：较低价格带来的销售量增加不足以弥补降价的影响。
7. Question 7 – Cross Elasticity of Demand | 第七题 – 需求交叉弹性
If a 10% rise in the price of margarine leads to a 6% increase in the quantity demanded for butter, the cross elasticity of demand is:
如果人造黄油价格上升 10% 导致黄油需求量增加 6%，则需求交叉弹性为：
Answer: D – +0.6, and the goods are substitutes.
答案：D – +0.6，且两种商品是替代品。
The formula is XED = %ΔQd of good A / %ΔP of good B. Here, +6% / +10% the two goods are substitutes: consumers switch from margarine to butter when margarine becomes relatively more expensive. If XED were negative, they would be complements. The magnitude shows a moderately strong substitutability.
公式为 XED = 商品A需求量变化百分比 / 商品B价格变化百分比。此例中 +6% / +10% = +0.6。正值 XED 表明两种商品是替代品：当人造黄油相对变贵时，消费者转向黄油。若 XED 为负，则为互补品。该值显示出中等强度的替代关系。
8. Question 8 – Maximum Price (Price Ceiling) | 第八题 – 最高限价
A government sets a maximum price for rented accommodation below the free‑market equilibrium. What is the most likely outcome?
政府将出租住房的最高限价设定在自由市场均衡价格之下。最可能的后果是：
Answer: B – A persistent shortage of rental housing.
答案：B – 出租住房持续短缺。
When a price ceiling is set below equilibrium, the quantity demanded exceeds the quantity supplied, creating an excess demand (shortage). Landlords have less incentive to offer properties, while more tenants seek cheap rents. This can lead to informal side‑payments, black markets, and a deterioration in housing quality. A surplus occurs with a price floor above equilibrium. Options C and D are not guaranteed outcomes.
当最高限价低于均衡价格时，需求量超过供给量，产生超额需求（短缺）。房东提供房源的激励减弱，而更多租户寻求低价住房。这可能导致非正式附加付款、黑市以及住房质量下降。过剩出现在支持价格高于均衡时。选项 C 和 D 并非必然结果。
9. Question 9 – Negative Externalities | 第九题 – 负外部性
A factory discharges waste into a river, harming local fisheries. This is an example of:
一家工厂将废料排入河中，损害了当地渔业。这是一个例子：
Answer: B – A negative production externality.
答案：B – 负的生产外部性。
The activity (production) generates a spillover cost to a third party not involved in the transaction. The private cost to the factory does not include the damage to fisheries, so the social cost exceeds the private cost. This leads to overproduction from society’s viewpoint. Negative consumption externalities arise from consumption activities (e.g., smoking in public). Public goods are non‑excludable and non‑rival, which is not the case here.
该活动（生产）给未参与交易的第三方带来了溢出成本。工厂的私人成本未包含对渔业的损害，因此社会成本大于私人成本。从社会角度看，这导致了过度生产。负的消费外部性来自消费活动（如公共场所吸烟）。公共品具有非排他性和非竞争性，与本例不符。
10. Question 10 – Public Goods | 第十题 – 公共品
Street lighting is often provided by the government because it is:
路灯通常由政府提供，因为它属于：
Answer: D – Non‑excludable and non‑rival.
答案：D – 非排他且非竞争性。
A public good has these two characteristics: once provided, no one can be effectively excluded from benefiting, and one person’s use does not reduce availability for others. This creates a free‑rider problem – private firms cannot profitably supply the good, so government intervention is justified. Rival goods (like a sandwich) diminish with consumption; excludable goods can prevent non‑payers from using them.
公共品具有这两个特征：一旦提供，无法有效排除任何人受益，且一人的消费不减少他人的可用量。这导致了搭便车问题——私营企业无法从提供该物品中盈利，因此政府干预是合理的。竞争性商品（如三明治）随着消费而减少；排他性商品可阻止未付费者使用。
11. Structured Question 1 – Determinants of PED | 简答题一 – 需求价格弹性的决定因素
Explain three factors that determine whether the price elasticity of demand for a product is likely to be elastic or inelastic.
请解释决定一种产品需求价格弹性可能富有弹性还是缺乏弹性的三个因素。
Model answer key points: (1) Availability of close substitutes – more substitutes make demand more elastic because consumers can easily switch. (2) Proportion of income spent on the good – expensive items take a larger share, so consumers are more price‑sensitive; thus demand tends to be more elastic. (3) Time period – demand is usually more elastic in the long run as consumers find alternatives and adjust habits. Other accepted factors include whether the good is a necessity or luxury, and addiction/habit formation.
参考答案要点：（1）相近替代品的可获得性——替代品越多需求越富弹性，因为消费者容易转向。（2）商品支出占收入的比例——昂贵物品占比高，消费者对价格更敏感，因此需求通常更富弹性。（3）时间周期——长期中需求通常更富弹性，因消费者可找到替代品并调整习惯。其他可接受因素包括商品是必需品还是奢侈品，以及成瘾或习惯形成。
A top‑band answer would also illustrate with examples, e.g., salt (inelastic because few substitutes and small budget share) versus a particular brand of breakfast cereal (elastic due to many close substitutes). For WJEC, clear definitions, correct terminology, and explicit links to elasticity values are essential.
高分段答案还会举例说明，例如食盐（缺乏弹性因替代品少且预算份额小）与某特定品牌早餐麦片（富有弹性因替代品多）。对 WJEC 考试而言，清晰的定义、正确的术语以及与弹性值的明确联系至关重要。
12. Structured Question 2 – Indirect Tax Diagram | 简答题二 – 间接税图解
Using a demand and supply diagram, analyse the impact of a per‑unit indirect tax on the market for sugary drinks. Include the effect on price, quantity, consumer and producer burden, and government revenue.
利用供求图，分析从量间接税对含糖饮料市场的影响。包括对价格、数量、消费者和生产者负担以及政府税收收入的影响。
ibrium at P1, Q1. Then shift the supply curve vertically upward by the full amount of the tax to S2 = S1 + tax. New equilibrium at P2 (higher) and Q2 (lower). The vertical distance between the old and new supply curves at Q2 equals the tax per unit. The rectangle between P2 and the net‑of‑ izes depend on the elasticities: demand for sugary drinks tends to be relatively inelastic, so consumers bear a larger share of the tax.
图示描述：绘制标准坐标轴，横轴为数量，纵轴为价格。初始需求 D 和供给 S1，均衡价格 P1、数量 Q1。然后将供给曲线向上垂直移动税额至 S2 = S1 + 税。新均衡价格 P2（更高），数量 Q2（更低）。在 Q2 处原供给曲线与新供给曲线之间的垂直距离等于单位税额。介于 P2 与税后净价（P3）之间乘以 Q2 的矩形代表政府税收收入。消费者负担为 (P2−P1)×Q2；生产者负担为 (P1−P3)×Q2。两者相对大小取决于弹性：含糖饮料的需求通常相对缺乏弹性，因此消费者承担较大税负。
Evaluation points for high marks: mention potential unintended consequences (e.g., cross‑border shopping, black markets), the regressive nature of the tax, and how the revenue could be used to fund health programmes. Also note that a diagram must be accurately labelled and accompanied by a step‑by‑step written explanation.
高分评价要点：提及潜在意外后果（如跨境购物、黑市）、税收的累退性质，以及税收收入如何用于资助健康项目。还需注意图解必须准确标注，并附有逐步的文字说明。
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