Demand · 需求
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| income/ˈɪŋkʌm/ | 收入 | shōu rù |
| law of demand/lɔː ɒv dɪˈmænd/ | 需求定律 | xū qiú dìng lǜ |
| demand/dɪˈmænd/ | 需求 | xū qiú |
| quantity demanded/ˈkwɒntɪti dɪˈmændɪd/ | 需求量 | xū qiú liàng |
| inverse relationship/ɪnˈvɜːs rɪˈleɪʃənʃɪp/ | 反向关系 | fǎn xiàng guān xì |
| substitution effect/ˌsʌbstɪˈtjuːʃn ɪˈfekt/ | 替代效应 | tì dài xiào yìng |
| substitute/ˈsʌbstɪtjuːt/ | 替代品 | tì dài pǐn |
| income effect/ˈɪŋkʌm ɪˈfekt/ | 收入效应 | shōu rù xiào yìng |
| movement along/ˈmuːvmənt əˈlɒŋ/ | 沿曲线移动 | yán qū xiàn yí dòng |
| shift/ʃɪft/ | 移动 | yí dòng |
| tastes/teɪsts/ | 偏好 | piān hǎo |
| complement/ˈkɒmplɪmənt/ | 互补品 | hù bǔ pǐn |
Why a sale empties the shelves
- Cut a price and a crowd appears; raise it and the crowd melts away.
- That predictable response is the single most important pattern in a market.
- Get it right and you can predict how buyers react to price, income, and fashion.
- It is called the law of demand 需求定律.
为什么一打折,货架就空了
- 降价,人群就涌来;涨价,人群就散去。
- 这种可预测的反应,是市场里最重要的一条规律。
- 弄懂它,你就能预测买家如何对价格、收入和潮流做出反应。
- 它叫做需求定律(law of demand)。
The law of demand
- Demand 需求 is the whole relationship between price and how much buyers want at each price — not one number.
- Quantity demanded 需求量 is just one number: the amount bought at one price.
- The law of demand: price up → quantity demanded down; price down → quantity demanded up. An inverse relationship 反向关系.
- The curve slopes down for two reasons: the substitution effect 替代效应 (switch to cheaper substitutes) and the income effect 收入效应 (your money buys less).
需求定律
- 需求(demand)是价格与买家在每个价格下想买多少之间的整体关系——不是一个数字。
- 需求量(quantity demanded)只是一个数字:在某一个价格下买的量。
- 需求定律:价格上升 → 需求量下降;价格下降 → 需求量上升。这是一种反向关系(inverse relationship)。
- 曲线向下倾斜有两个原因:替代效应(substitution effect,转向更便宜的替代品)和收入效应(income effect,钱的购买力变小)。
Demand and supply · 需求与供给
The demand curve slopes down — a lower price, more is wanted. A change in income or tastes shifts the whole curve. · 需求曲线向下倾斜——价格更低,想要的更多。收入或偏好的变化会移动整条曲线。
The law of demand says that, other things equal, when price rises the quantity demanded: · 需求定律说,其他条件相等,当价格上升时,需求量:
Price and quantity demanded move in opposite directions — an inverse relationship. · 价格与需求量方向相反——反向关系。
The amount buyers will buy at one particular price is called: · 买家在某一个特定价格下会买的量,叫做:
Quantity demanded is one number; demand is the whole price–quantity relationship. · 需求量是一个数字;需求是整个价格—数量关系。
Movement vs shift
- A change in the good's own price → a movement along 沿曲线移动 the curve (a change in quantity demanded).
- A change in anything else → a shift 移动 of the whole curve (a change in demand).
This distinction wins marks. Only the good's own price moves you along the curve. Income, tastes, or other prices shift it. Mixing these up is the classic exam mistake.
沿曲线移动 vs 曲线移位
- 商品自身价格的变化 → 沿曲线移动(movement along),即需求量的变化。
- 其他任何因素的变化 → 整条曲线的移位(shift),即需求的变化。
这个区分能拿分。只有商品的自身价格让你沿曲线移动。收入、偏好或其他商品价格会移动整条曲线。混淆它们是经典的考试错误。
A change in the good's own price causes a movement along the demand curve, not a shift. · 商品自身价格的变化引起沿需求曲线的移动,而不是移位。
Own price → movement along; every other factor → shift of the whole curve. · 自身价格 → 沿曲线移动;其他任何因素 → 整条曲线移位。
What shifts demand — TIPEN
- Tastes 偏好: a good becomes popular → demand shifts right.
- Income 收入: for a normal good, higher income → demand right.
- Prices of related goods: a cheaper substitute 替代品 shifts this good's demand left; a cheaper complement 互补品 shifts it right.
- Expectations of higher future prices → buy more now (right). Number of buyers rises → right.
什么会移动需求 —— TIPEN
- T 偏好(tastes):某商品变流行 → 需求右移。
- I 收入(income):对正常商品,收入更高 → 需求右移。
- P 相关商品价格:更便宜的替代品(substitute)使本商品需求左移;更便宜的互补品(complement)使它右移。
- E 预期(expectations)未来涨价 → 现在多买(右移)。N 买家数量(number of buyers)增加 → 右移。
Match each change to its effect on the demand for coffee. · 把每个变化与它对咖啡需求的影响配对。
Income, substitutes and complements shift the curve; the good's own price only moves you along it. · 收入、替代品和互补品移动曲线;商品自身价格只让你沿曲线移动。
Two goods used together, like printers and ink, are called . · 一起使用的两种商品,比如打印机和墨水,被称为。
A rise in the price of one lowers demand for the other. · 一个的价格上升会降低对另一个的需求。
Select all · 所有 that shift the demand curve (rather than move along it). · 选出所有会移动需求曲线(而非沿曲线移动)的因素。
TIPEN factors shift the curve; the good's own price only causes a movement along it. · TIPEN 因素移动曲线;商品自身价格只引起沿曲线移动。
Demand is the whole price–quantity relationship; the law of demand makes it slope down (substitution + income effects). The good's own price = a movement along; any other factor (TIPEN) = a shift of the whole curve.
需求是价格与数量的整体关系;需求定律使它向下倾斜(替代效应 + 收入效应)。商品的自身价格 = 沿曲线移动;其他任何因素(TIPEN)= 整条曲线的移位。