单选题 {{B}}Passage 5{{/B}}
The average population density of the world is 47 persons per square mile. Continental densities range from no permanent inhabitants in Antarctica to 211 per square mile in Europe. In the western hemisphere, population densities range from about 4 per square mile in Canada to 675 per square mile in Puerto Rico. In Europe the range is from 4 per square mile in Iceland to 831 per square mile in the Netherlands. within countries there are wide variations of population densities. For example, in Egypt, the average is 55 persons per square mile, but 1,300 persons inhabit each square mile in settled portions where the land is arable.
High population densities generally occur in regions of developed industrialization, such as the Netherlands, Belgium, and Great Britain, or where lands are intensively used for agriculture, as in Puerto Rico and Java.
Low average population densities are characteristic of most underdeveloped countries. Low density of population is generally associated with a relatively low percentage of cultivated land. This generally results from poor-quality lands. It may also be due to natural obstacles to cultivation, such as deserts, mountains or malaria-infested jungles, to land uses other than cultivation, as pasture and forested land, to primitive methods that limit cultivation, to social obstacles, and to land ownership systems which keep land out of production.
More economically advanced countries of low population density have, as a rule, large proportions of their populations living in urban areas. Their rural population densities are usually very low. Poorer developed countries of correspondingly low general population density, on the other hand, often have a concentration of rural population living on arable land, which is as great as the rural concentration found in the most densely populated industrial countries.
单选题 Along the banks of the Nile, we may expect to find ______.
【正确答案】 D
【答案解析】沿着尼罗河两岸,我们可以看到许多移民区。答案的依据是第一段最后一句。作者说,在埃及,平均人口密度是每平方英里55人,但是在适宜耕种的移民区每平方英里有1 300个人居住。第一段最后一句中的settled portions与settlements是同义词,可以大胆地选,因为有些答案与文中的某个词、短语的意思是相同的。
单选题 In timberland areas of the world, ______.
【正确答案】 C
【答案解析】在世界上的林区,人口密度很低。作者在第三段说,人口密度低往往与可耕地面积的比例不高有一定的联系。人口密度低一般是由于土地贫瘠造成的,也有可能是由不利于耕种的天然障碍造成的,如沙漠、山区或疟疾肆虐的丛林。
单选题 The title below that best expresses the main idea of this passage is ______.
【正确答案】 D
【答案解析】表达本文大意的最佳标题是:人口密度(Population Densities)。本文作者谈到世界上一些国家的人口密度。讲到自然环境对人口密度的影响以及经济环境对人口密度的影响,所以选D最合适。
单选题 This passage has probably been taken from ______.
【正确答案】 D
【答案解析】这篇短文很可能选自一本关于世界地理的书籍。这篇短文提到世界上许多国家,并指出了它们.的人口密度,因此最有可能是地理书。A(gazeteer地名词典,地名索引),B(almanac年鉴),C(textbook on economics与经济学有关的教科书)的可能性不大。