单选题

Specialization and International Trade

The high (21) of specialization in our society increases the standard of living of all by making more goods and services available. But specialization necessarily implies trade and can not occur without it. This (22) from the fact that people usually want to have a "(23) diet. " The specialized producer uses only a small part-maybe none-of his own product for his personal (24) and he exchanges his surplus for the goods and services of other specialized producers.
The exchange of goods and services among residents of the same country is usually called (25) trade. Countries cannot live alone any more effectively than individuals can. Thus, each country tends to specialize in the production of those commodities which it can produce relatively more (26) than other countries, exchanging its surplus for the (27) of other countries, of goods and services which they produce relatively more cheaply, or which the first country cannot produce at all. This process brings (28) an international division of labor which makes it possible to make more goods and services available to all countries. (29) the inter national division of labor and specialization increases the standard of living in all countries in the same way that the division of labor and specialization within a single, (30) economy increases the standard of living of all of its residents.