15．In 1800，only three percent of the world's population lived in cities．Only one city-Beijing-had a population of over a million．Most people lived in rural areas，and never saw a city in their lives．In 1900，just a hundred years later，roughly 150million people lived in cities，and the world's ten largest cities all had populations exceeding one million．By 2000，the number of city dwellers exceeded three billion； and in 2008，the world's population crossed a tipping point-more than half of the people on Earth lived in cities．By 2050，that could increase to over two-thirds．Clearly，humans have become an urban species．
In the 19th and early 20th centuries，many people viewed cities negatively-crowded，dirty environments full of disease and crime．They feared that as cities got bigger，living conditions would worsen．In recent decades，however，attitudes have changed．Many experts now think urbanization （城市化） is good news，offering solutions to the problems of Earth's growing population．
Harvard economist Edward Glaeser，author of The Victory of the Cir，is one such person．Glaeser argues that cities are very productive because"the absence of space between people"reduces the cost of transporting goods，people，and ideas．While the flow of goods has always been important to cities，what is most important today is the flow of ideas．Successful cities enable people to learn from each other easily，and attract and reward smart people with higher wages．
Another urbanization supporter is environmentalist Stewart Brand．Brand believes cities help the environment because they allow haft of the world's population to live on about four percent of the land．This leaves more space for open country，such as farmland．City dwellers also have less impact per person on the environment than people in the countryside．Their roads，sewers，and power lines need fewer resources to build and operate．City apartments require less energy to heat，cool，and light．Most importantly，people in cities drive less so they produce fewer greenhouse gases per person．
So it's a mistake to see urbanization as evil； it's a natural part of development．The challenge is how to manage the growth．
4．What is Paragraph 1mainly about？C
A．The history of modern cities．
B．Changes taking place within cities．
C．How cities have grown over time．
D．Why modern cities are changing．
5．How have experts'attitudes towards cities changed in recent decades？A
A．They now view the weaknesses as strengths．
B．They no longer see city-riving as attractive．
C．They accept city life in spite of its problems．
D．They think city-riving provides more benefits．
6．Which of the following would Edward Glaeser agree with？B
A．Cities provide more economic opportunities．
B．City people get along better with each other．
C．Over-crowded cities result in problems．
D．Cities limit the flow of ideas．
7．According to Paragraph 4，what would be the result of moving people out of cities？D
A．Economic production would be reduced．
B．There would be less farmland available．
C．People would travel less frequently．
D．House values would fall greatly．
分析 本文屬于說明文閱讀，作者通過這篇文章向我們介紹了城市中的人口是如何隨著時間而增長的，以及城市化的好處以及劣勢．
解答 4．C 推理判斷題，根據(jù)第一段in 2008，the world's population crossed a tipping point-more than half of the people on Earth lived in cities．By 2050，that could increase to over two-thirds．可知第一段主要向我們介紹了城市中的人口是如何隨著時間而增長的，故選C．
5．A 細節(jié)理解題，根據(jù)第二段In the 19th and early 20th centuries，many people viewed cities negatively-crowded，dirty environments full of disease and crime．以及Many experts now think urbanization （城市化） is good news，offering solutions to the problems of Earth's growing population可知在十九世紀和二十世紀初，許多人認為城市擁擠骯臟的環(huán)境中充滿了消極，疾病和犯罪，而現(xiàn)在專家們認為城市化是個好消息，故選A．
6．B 細節(jié)理解題，根據(jù)第三段Successful cities enable people to learn from each other easily，and attract and reward smart people with higher wages．可知Edward Glaeser 認為城市化中的人與人之間相處的更好，故選B．
7．D 細節(jié)理解題，根據(jù)第四段City dwellers also have less impact per person on the environment than people in the countryside．Their roads，sewers，and power lines need fewer resources to build and operate．City apartments require less energy to heat，cool，and light可知如果人們搬離城市，那么城市中的房價將大幅下跌，故選D．
點評 考查學生的細節(jié)理解和推理判斷能力．做細節(jié)理解題時一定要找到文章中的原句，和題干進行比較，再做出正確選擇．在做推理判斷題時不要以個人的主觀想象代替文章的事實，要根據(jù)文章事實進行合乎邏輯的推理判斷．
