Questions 51 to 55 are based on the following passage.-|||-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 agriculurnl proction comp 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.-|||-注意:此部分试题请在答题卡2上作答。-|||-51.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-|||-52.What is the most important to agriculture is __ .-|||-Directions: there are 2 passages in this section. Each passage is followed by some questions or-|||-unfinished statements For each of them there are four choices marked A ),B),C)and D).You-|||-should decide on the best choice and mark the corresponding letter on Answer Sheet 2 with a-|||-single line through the centre.-|||-A)the amount of food it produces-|||-B) the per capita income of farmers-|||-C)its industrial performance-|||-D)the production of investment goods-|||-53.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-|||-54.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-|||-55.This passage will most probably be followed by a discussion of __ 一-|||-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