Mega-citiesIn 1950, New York was the only city with more than 10 million inhabitants. There are now 11cities housing over 11 million people each. Tokyo alone has 17 million. In 1995, their combined population totaled 166 million; in 2015 it is forecast to be over 204 million.The worlds urban population, increasing at four times the rate of rural populations, will double in the period 1990-2025, to over five billion. Consequently, two-thirds of the people of the world will live in cities, some of which will be huge. Moreover, about 90% of the growth will be in developing countries. This growth, adding around 60 million people per year to city population, will be mainly in Southeast Asia and Africa. The consequences are dramatic. This is change on a scale never before experienced, bringing with it considerable challenges and opportunities.Why does this growth happen? Most of it results from internal migration rather than the international movement of people, and is caused by a variety of push and pull factors.One push factor is due to pressure on land availability. Improved health brings population growth, causing people to move out of rural areas. Others move because of climate change or poor farming methods which often result in deforestation and flooding. Such changes can alter the social structure, leading people to move. Furthermore, civil war or regional conflicts also cause disruption, driving people out of rural areas.On the other hand, there are the pull factors. Cities attract people because of the demand for labor in the manufacturing and service industries. As a result, they offer a higher standard of living to the lucky ones. Cities also tend to offer greater personal freedom.The world economy has expanded five-fold since 1950, with the cities driving the expansion. Much of this economic expansion has been in the developing countries of Southeast Asia. Therefore, most of the mega-cities of the future will be found there.题目1The combined total population of these 11 cities _.选择一项：a. was 166 million in 1950b. was 17 million in 1995c. is 204 million nowd. will be over 204 million in 2015 答案为D。此题可以运用查读技巧。先在找到第一段中找到包含题中关键信息（The combined total population）的句子，即第一段最后一句，于是可以直接得出选项D。而其他选项虽都在文中提到，但都不是与题干相对应的，因此可排除A，B，C三项。题目2The worlds rural population _.选择一项：a. increased at one fourth the rate of urban population b. increased at four times the rate of urban populationc. will be four times bigger by 2025d. will double in the period 1990-2025答案为A。此题需要运用查读技巧，并考查计算能力。先找到文中第二段的第一句，“The worlds urban population, increasing at four times the rate of rural populations” 城镇人口正以4倍于农村人口的速度增长着，即农村人口的增长速度的城镇人口的1/4。因此,不要被选项B所迷惑而误选。题目3Which of the following is true according to this passage? _.选择一项：a. There are now 11 cities with a total population of 11 million people.b. The worlds urban population will be four times bigger by 2025c. Various push and pull factors cause people to move 正确d. Two-thirds of the worlds population will live in cities in Southeast Asia and Africa.答案为C。此题可以运用查读技巧。找出选项A应为“There are now 11 cities with a population of 11 million people each.”选项B应改为“It will double by 2025.”选项D应将“in Southeast Asia and Africa”改为“all over the world”。因此，正确答案为选项C多种内、外因引起人口流动。题目4People choose to leave rural areas partly because _.选择一项：a. climate change or poor farming methods result in deforestation and flooding 正确b. the living standards of cities are much lowerc. the population of rural areas increased faster than that of urban areasd. there are not enough space for people to live there答案为A。 此题考查仔细阅读和分析的能力。文章第四段说明了人们纷纷离开农村的一些原因。四个选项中，只有选项A谈到了气候的改变和落后的农业方法使得山林遭到砍伐，洪水泛滥，这是人们选择离开农村的原因之一。而其他选项均不是文中列举出的原因。题目5We can conclude from the last paragraph that_.选择一项：a. the world economy has declined since 1950b. economic expansion leads to mega-cities 正确c. the expansion is mainly taking place in Europed. there isnt any economic expansion in the developing countries答案为B。此题可以运用查读技巧。题干中已道明此题考查的范围，因此直接在最后一段中进行查读。第一句话讲“自1950年以来城市的发展促使世界经济出现了五倍的扩张”，因此选项A经济下降显然不对；第二句接着讲“大部分的经济扩张发生在东南亚这样的发展中国家”，因此,选项C讲经济扩张发生在欧洲也是错误的；选项D讲经济扩张没发生在发展中国家显然也不正确。通过分析可逐一排除选项A、C、D而得出正确答案B。A Case Study: Desertification around the GobiDesertThe ProblemsThe GOBIDesert, in the north of China, is now seven times bigger than Britain. China has large desert areas and much of its agricultural land is being threatened by desertification, which is getting worse. In addition, soil erosion has led to a huge loss of farmland and the drying up of rivers. Consequently, the livelihoods of 35 million people are being threatened. Furthermore it is even affecting cities. The nearest sand dune is less than 100 miles from Beijing, where unpleasant sandstorms are becoming more frequent. The worse the situation, the more pressure there is on the government to take action.The CausesThe reasons for the changes are complex. It is clear th