1.International trade is the exchange of goods and services produced in one country for goods and services produced in another country. There are several reasons why international trade exists.
1、国际贸易是一个国家所生产的商品和服务和另一个国家所生产的商品和服务之间的交换。这样做的原因是多方面的。
2.The distribution of natural resources around the world is somewhat haphazard: some nations possess natural deposits in excess of their own requirements while other nations have none. For example, Britain has large reserves of coal but lacks many minerals such as nickel, copper, aluminum, etc.， whereas the Arab states have vast oil deposits but little else. In the cultivation of natural products climate plays a decisive role. Some products will only grow in tropical climates whereas others, such as citrus fruits，require a Mediterranean climate. Moreover, some nations are unable to produce sufficient quantities of a particular product to satisfy a large home demand. For example, Britain does not produce enough wheat to meet the needs of its population. These are the reasons why international trade first began.
2、世界自然资源的分布是带有随意性的。有些国家所拥有的天然资源超过了本身的需要，而别的国家则没有。例如，英国煤的储藏量很丰富，但是很多矿藏，如镍、铜和铝等都很缺乏;阿拉伯国家拥有巨大的石油矿藏，但是其他资源则很少。在天然作物的培育过程中，气候起到决定性的作用。有一些作物只适宜在热带气候的条件下生长，而像柑桔类的水果等其他作物则需要地中海型的气候。此外，有些国家的某个产品的生产不能满足国内的巨大需求，例如英国的小麦就是这样。这些就是国际贸易开始出现的原因。
3.With the development of manufacturing and technology, there arose another incentive for nations to exchange their products. It was found that it made economic sense for a nation to specialize in certain activities and produce those goods for which it had the most advantages，and to exchange those goods for the products of other nations which had advantages in different fields. This trade is based on the principle of comparative advantage.
3、随着制造业和技术的发展，出现了新的因素促使国家之间进行产品交换。人们发现，如果一个国家专门从事一定的生产活动，生产它拥有优势的产品，并用这些商品同在其他方面拥有优势的国家所生产的产品进行交换，那在经济上是合算的。这种贸易是在比较优势原则的基础上进行的。
4.The theory of comparative advantage, also called the comparative cost theory, was developed by David Ricardo and other economists in the nineteenth century. It points out that trade between countries can be profitable for all. Even if one of the countries can produce every commodity more cheaply，as long as there are minor relative differences in the efficiency of producing a commodity even the poor country can 'have a comparative advantage in producing it. The paradox is best illustrated by this traditional example: the best lawyer in town is also the best typist in town. Since this lawyer cannot afford to give up precious time from legal affairs，a typist is hired who may be less efficient than the lawyer in both legal and typing matters. But the typist’s comparative disadvantage is least in typing. Therefore, the typist has a relative comparative advantage in typing.
4、比较优势学说又称比较成本学说，是由大卫_李嘉图和其他19世纪的经济学家所建立的。该理论指出，即使有某个国家能以较低的成本生产每一种商品，国家之间的贸易对所有国家仍会有好处。只要在生产一种商品的效率上存在着小的相对的差别，即使是穷国在生产上也会有比较优势。这种似非而是的理论能够用下面的传统例子最恰当地予以说明。某城的律师同时也是的打字员。这个律师不能放弃他处理法律事务的宝贵时间，就雇用了一名打字员。这个打字员可能在法律和打字方面都不如这位律师，但是这个打字员的相对劣势在打字方面是最小的。因此，这名打字员在打字方面就有比较优势。
5.This principle is the basis of specialization into trades and occupations. At the same time, complete specialization may never occur even when it is economically advantageous. For strategic or domestic reasons, a country may continue to produce goods to which it does not have an advantage. The benefits of specialization may also be affected by transport costs: goods and raw materials have to be transposed around the world and the cost of the transport narrows the limits between which it will prove profitable to trade. Another impediment to the free flow of goods between nations is the possible introduction of artificial barriers to trade, such as tariffs or quotas.
5、这个原则是实行贸易和职业专业分工的基础。但是，完全的专业分工可能永远也不会实现，即使从经济的角度来看是有利的。由于战略和国内的原因，一个国家可能仍然要生产它并不具有优势的产品。专业分工的好处也可能会受到运输费用的影响，因为要在世界范围内进行货物和原料的运输，运输的费用使得贸易获利的范围缩小。国家之间货物自由流通的另一个障碍是可能采用人为的贸易壁垒，例如关税和配额。
6.In addition to visible trade，which involves the import and export of goods and merchandise, there is also invisible trade, which involves the exchange of services between nations.
6、除了有形贸易(即指商品和货物的进出口)以外，还有无形贸易。这是指国家之间服务的交换。
7.Nations such as Greece and Norway have large maritime fleets and provide transportation service. This is a kind of invisible trade. When an exporter arranges shipment, he rents space in the cargo compartment of a ship.
7、希腊、挪威等国拥有庞大的海运船队。提供运输服务，这是无形贸易的一种。当一个出口商安排货运时，他就可以租用船只货舱的舱位。
8.The prudent exporter purchases insurance for his cargo’s voyage. While at sea, a cargo is vulnerable to many dangers. Thus，insurance is another service in which some nations specialize. Great Britain, because of the development of Lloyd’ of London, is a leading exporter of this service, earning fees for insuring other nations，foreign trade.
8、谨慎的出口商为他的货物运输办理保险。在海上，货物会遇到各种危险。所以一些国家专门从事保险服务。由于伦敦劳埃德保险公司的发展，英国是这种服务的主要出口国，它为其他国家的对外贸易承担保险而赚取费用。
9.Some nations possess little in the way of exportable commodities or manufactured goods, but they have a mild and sunny climate. During the winter, the Bahamas attract large numbers of tourists who spend money for hotel accommodation, meals, taxis, and so on. Tourism, therefore, is another form of invisible trade.
9、有些国家没有可供出口的初级产品或者制成品，但是这些国家风和日丽、气候宜人。在冬季，巴哈马群岛吸引着大量的旅游者，他们住旅馆、就餐、坐出租汽车等方面都要花钱。因此，旅游业是无形贸易的另一种形式。
10.Invisible trade can be as important to some nations as the export of raw materials or commodities is to others. In both cases, the nations earn money to buy necessities.
10、无形贸易对一些国家来说，就像原料和商品的出口对别的国家那样重要。在这两种情况下，这些国家都能赚到钱去购买他们所需要的商品。
