In the study of economics, all the interactions between supply, demand, and price are usually expressed by mathematical formulas. These formulas are often illustrated by points on a graph. Imagine a graph with price on one side and quantity （supply） on the other.
在经济学的研究中，所有关于供给，需求，价格的互相作用时常可以用数学公式表达出来。这些公式经常以图形的方式出现。想象一下，一张图表的一边是价格，另外一边是商品的供给数量。
The points where the price and quantity intersect represent the demand. The same is true of a graph that shows supply. These graphs show how supply, demand, and price interact.
需求的变化表现为价格和商品的数量之间的互相影响。 同样的图表也能揭露供给的变化。这些图标展示了供给，需求和价格，三者之间如何互相影响。
A DELICATE BALANCE
微妙的平衡
In a perfect economic world, supply and demand would always be balanced, or be equal, a condition called equilibrium. The amount of goods available would exactly equal the demand for those goods. Sellers would be selling, buyers would be buying, and everyone would be happy.
在一个完美的经济世界，供给与需求总是平衡的，或者相等，这种情况叫做均衡。 可够被购买的商品数量精确的等于对这个商品的需求量。 销售人员会卖掉商品，购买者会购买商品，然后大家都很开心。
This can be shown on a supply and demand graph as a perfect intersection, creating a giant X on the graph.
供给与需求恰到好处的相互作用，呈现下面这张供需表中，可以看到两条线构造出一个巨大的X。
Supply and demand can be represented in a graph.
供给和需求能够被一张图表所呈现出来。
However, economic equilibrium in supply and demand really only exists in theory. It doesn’t happen in the real world, because supply and demand, affected by many different factors, are constantly changing. Many factors can result in disequilibrium, when supply and demand aren’t balanced.
然后，供给与需求中的经济均衡只存在于理论中。它不会发生在现实世界。因为，供给与需求会被很多不同的因素影响，会不断的发生变化。 当供需失衡时，许多因素都会导致不平衡。
Maybe the price for a good or service is too high, so demand is low. Or the price for something is low and many people want it, but sellers run out.
可能是某种商品或服务的价格过高，导致需求下降。或者是价格过低，导致许多人想要购买，但没有供货商。
This graph shows equilibrium, which happens when the amount of goods available exactly equals the demand for those goods.
图表中表现了均衡，它只会发生在供需高度一致的时候。
MORE EXCEPTIONS TO THE RULES.
规则中的更多例外
Rules can almost always be broken. There are situations where the economic “rules” are actually broken in the markerplace. One example is something called a Giffen good. This type of good is in greater demand as its price rises, especially if a related good becomes more expensive.
规则总是被打破。在市场中有很多时候都不符合经济学的原则。例如一种叫做Giffen good的商品，这是一种即使在价格上涨的情况下，需求依然有增不减，特别是在于Giffen good相关的原材料产品。
It’s also often a lower-quality product without any easily available substitutes. Staple foods – something that many people rely on to eat every day – are a good example of a Giffen good. Imagine that rice becomes more expensive. People who buy it would have less moeny to buy more expensive foods lie flour.
也有一种质量低下，很难找到替代品的商品。名为Staple food，是许多人每天必须要吃的食品，这是一种典型的Giffen good。 想象一下，大米变得更加贵，那些购买花了更多预算去购买大米的人，会同时花更少的人去购买与面粉相关的食物。
So they would end up having to buy more rice, because they can’t afford the more expensive foods and need to compensate by buying more rice to eat.
所以他们最终不得不购买更多的大米，因为它们不能承受更昂贵的食物，所以购买更多的大米去作为补偿。
Many people rely on rice – an example of a Giffen good – to eat every day. If it becomes expensive, they give up more expensive foods and buy more rice to compensate.
很多人每天依赖于吃米饭—一种Giffen good的例子 。如果米变得昂贵，他们会放弃一些昂贵的食物，去买更多的米作为补偿。
Goods with “snob appeal,” like this Lamborghini car, are examples of Veblen goods. Luxury goods like this may give the people who buy them a higher social status.
有很多 snob appeal，例如兰博基尼汽车，是Veblen goods的例子。像兰博基尼这种奢侈品使那些愿意购买它的人得到更高的社会地位。
Veblen goods伯伦商品，又称炫耀财，是经济学上用以描述一种商品，其特色是商品需求与商品价格成正向关系，而非正常需求法则的反向关系。
snob appeal 的解释：Snob appeal refers to the qualities or attributes of a product that might appeal to a consumer with “snobby” tastes. It may refer to the actual product itself or the exclusivity the consumer could potentially experience as a result of owning the product that is being advertised.
Veblen goods are also goods that increase in demand as their price increases. Unlike Giffen goods, these goods are high-quality status symbols(status symbols), like expensive sports cars or designer clothing. Veblen goods are usually marketed as being “exclusive” and make consumers who buy them feel successful and important.
Veblen goods 也是一种当需求增加时，价格也会上升的。与Giffen goods不同的是，这些商品具有高质量的地位象征，就好比跑车和时装。Veblen goods经常被当做是某些社会阶层“专有的”，让那些愿意购买他们的顾客感到成功。
They might have a strong brand name(brand name 商标；品牌名称) identity, like a Lamborghini car or Tiffany jewelry, and they may be available only in boutique stores(boutique stores 精品商店), not department sotres(department stores 百货公司). This gives these products more “snob appeal,” since the people who buy them are very conscious of their social status.
他们拥有一个强而有力的商标，就像兰博基尼跑车和蒂芙尼珠宝，他们通常在在精品商店有售，而不是百货公司。这些都让此类商品表现得更加“snob appeal”，因为愿意购买这些商品的人会非常在意他们的社会地位。
bontique shop的解释：A boutique shop is actually a specialized type of retail store. It is distinct from other retail businesses based on its more limited size, scope and inventory.
A boutique (French: [butik]) is “a small store that sells stylish clothing, jewellery, or other usually luxury goods”.[1
The higher the price gets, the more appeal(魅力) the good has. The buyers of Veblen goods usually have a great deal of money.
商品的价格越高，就越吸引人。购买Veblen goods的顾客通常在经济上会比较富足。
Vablen luxury goods aren’t just for adults. Many teens and young adults buy certain brand-name items, like jeans, because they are popular and expensive.
Vablen luxury goods不是只吸引成年人。许多青少年和年轻人都会购买特定品牌的商品，例如牛仔库，因为它们更加流行和价格贵。
NO PERFECT COMPETITION
没有完美的竞争
All ruls in economics operate with the assumption that the market has perfect competition. This would mean that in the marketplace, all buyers and sellers are alike and no one has more power to infulence price than anyone else. This isn’t how the real world works.
经济学中的所有规律都存在一个前提，就是市场充分竞争。这意味着，市场上的所有买家和卖家都比较相似，没有一个人拥有超过其他人的力量去影响价格。可现实世界不是这样运作的。
The Bell Telephone Company, owned by AT&T, once had a monopoly on US telephone service. But in 1982, the government ruled that they could no longer control the phone industry.
Bell Telephone Company, 拥有 AT&T, 一度垄断美国电话服务。在1982年，政府规定他们不可以再控制电话行业。
Some individuals or groups of buyers and sellers have enough power to influence pricing more than others. They might have a powerful brand name to sell.
一些群体、卖家、商家比其他人拥有更多的力量去影响价格。 他们拥有更出名的商品去出售。
They might be a group of buyers who supply a chain of big stores and are able to buy a great deal of merchandise(n. 商品；货物) at once. if either buyers or sellers can directly influence the price of something, the market won’t react according to the economic rules.
Sometimes there might be a product with only one supplier, which is called a monopoly. The company that is the supplier can set any price it want because it is the only one who can supply the product.
Demand by consumer will determine how much of that product is bought, but it won’t influenct the price at all. Some US industries, like the telephone system, were once monopolies.
All telephone service went through one company, the Bell System, owned by AT&T. Consumers had to pay whatever price that company set for its products. However, in 1982, the US goverment ruled that the Bell System could no longer have a monopoly on phone service.