As supplier of most of the food we eat and of raw materials for many industrial processes, agriculture is clearly an important area of the economy. But the industrial performance of agriculture (the relative efficiency of agricultural production compared to other areas in the economy) is even more important than this. For in nations where the productivity of farmers is low, most of the working population is needed to raise food and few people are available for the production of investment goods or for other activities required for economic growth. Indeed, one of the factors related most closely to the per capita income (人均收入) of a nation is the fraction of its population engaged in farming. In the poorest nations of the world more than half of the population lives on farms. This compares sharply with less than 10 percent in western Europe and less than 4 percent in the United States.
　　In short, the course of economic development in general depends in a fundamental way on the performance of farmers. This performance, in turn, depends on how agriculture is organized and on the economic environment, or market structure, within which it functions. In the following pages the performance of American agriculture is examined. It is appropriate to begin with a consideration of its market structure.

　　26. This passage is most probably ________.
　　A) a news item
　　B) part of an introduction to a book
　　C) part of a lecture
　　D) an advertisement（C）

　　27. What is the most important to agriculture is ________.
　　A) the amount of food it produces
　　B) the per capita income of farmers
　　C) its industrial performance
　　D) the production of investment goods（C）

　　28. The underlined word “this” in the first paragraph refers to ________.
　　A) the provision of food and raw materials
　　B) the productivity of farmers
　　C) the production of investment goods
　　D) the economy as a whole（A）

　　29. The performance of farmers essentially determines ________.
　　A) the size of the working population
　　B) the organization of agriculture
　　C) the market structure
　　D) the general development of economy（D）

　　30. This passage will most probably be followed by a discussion of ________.
　　A) the structure of American farming population
　　B) the market structure of American agriculture
　　C) the various functions of American agriculture
　　D) the organization of American agriculture（B）