外文翻译---供给与需求的市场力量(编辑修改稿)

外文翻译---供给与需求的市场力量(编辑修改稿)内容摘要：

y of market types we find in the world， we begin by studying perfect petition． Perfectly petitive markets are the easiest to analyze． Moreover， because some degree of petition is present in most markets， many of the lessons that we learn by studying supply and demand under perfect petition apply in more plicated markets as well． DEMAND We begin our study of markets by examining the behavior of buyers． Here we consider what determines the quantity demanded of any good， which is the amount of the good that buyers are willing and able to purchase． To focus our thinking， let39。 s keep in mind a particular good— ice cream． WHAT DETERMINES THE QUANTITY AN INDIVIDUAL DEMANDS Consider your own demand for ice cream． How do you decide how much ice cream to buy each month， and what factors affect your decision? Here are some of the answers you might give． Price： If the price of ice cream rose to $20 per scoop， you would buy less ice cream． You might buy frozen yogurt instead． If the price of ice cream fell to $0． 20 per scoop， you would buy more． Because the quantity demanded falls as the price rises and rises as the price falls，we say that the quantity demanded is negatively related to the price． This relationship between price and quantity demanded is true for most goods in the economy and， in fact， is so pervasive that economists call it the law of demand： Other things equal， when the price of a good rises， the quantity demanded of the good falls． Ine： What would happen to your demand for ice cream if you lost your job one summer? Most likely， it would fall． A lower ine means that you have less to spend in total， so you would have to spend less on some—and probably most— goods． If the demand for a good falls when ine falls， the good is called a normal good． Not all goods are normal goods． If the demand for a good rises when ine falls， the good is called an inferior good． An example of an inferior good might be bus rides． As your ine falls， you are less likely to buy a car or take a cab， and more likely to ride the bus． Prices of Related Goods Suppose： that the price of frozen yogurt falls． The law of demand says that you will buy more frozen yogurt． At the same time， you will probably buy less ice cream． Because ice cream and frozen yogurt are both cold， sweet， creamy desserts， they satisfy similar desires． When a fall in the price of one good reduces the demand for another good， the two goods are called substitutes． Substitutes are often pairs of goods that are used in place of each other， such as hot dogs and hamburgers， sweaters and sweatshirts， and movie ticketsand video rentals． Now suppose that the price of hot fudge falls． According to the law of demand， you will buy more hot fudg。