46. What do we learn from the passage about cities in sub-Saharan Africa?
- A. They have more slums than other cities in the world.
- B. They are growing fast without becoming richer.
- C. They are as modernized as many cities elsewhere.
- D. They attract migrants who want to be better off.
答案：B
答案句：What's indisputable is that it's growing very quickly Between now and 2050, the urban population of Africa could triple. Yet cities in sub-Saharan Africa are not getting richer the way cities in the rest of the world have. Most urban Africans live in slums(贫民窟); migrants are often not much better off than they were in the countryside.
参考译文：无可争议的是，它正在快速增长。从现在到2050年，非洲的城市人口可能会增加两倍。然而，撒哈拉以南非洲的城市并没有像世界其他地区的城市那样变得更加富裕。大多数非洲城市居民生活在贫民窟；移民往往并不比他们在农村时富裕多少。
定位线索：题干“cities in sub-Saharan Africa”→答案句“cities in sub-Saharan Africa are not getting richer”；文中“growing very quickly”对应选项B“growing fast”；文中“not getting richer”对应选项B“without becoming richer”。
解析：题干问关于撒哈拉以南非洲城市我们能了解到什么。答案句明确指出这些城市“growing very quickly”（增长非常快）但“not getting richer”（没有变得更富裕），与选项B“They are growing fast without becoming richer”完全对应。选项A“贫民窟比其他城市多”无中生有，文中只说大多数城市居民住在贫民窟，未比较；选项C“现代化程度高”与原文相反；选项D“吸引移民”虽提及移民，但未说他们想变得更好，且原文说他们并未变好。
48. Why is sub-Saharan Africa unappealing to investors?
- A. It lacks adequate transport facilities.
- B. The living expenses there are too high.
- C. It is on the whole too densely populated.
- D. The local governments are corrupted.
答案：A
答案句：Without upgrades and new capacity, bridges, roads and power systems are unable to cope with expanding populations. With the exception of South Africa, the only light rail metro system in sub-Saharan Africa is in Addis Ababa, Ethiopia. Traffic jam leads to expense and unpredictability, things that keep investors away.
参考译文：如果没有升级和新能力，桥梁、道路和电力系统将无法应对不断增长的人口。除了南非，撒哈拉以南非洲唯一的轻轨地铁系统在埃塞俄比亚的亚的斯亚贝巴。交通堵塞导致费用和不可预测性，这些使投资者望而却步。
定位线索：题干“unappealing to investors”→答案句“keep investors away”；文中“Traffic jam”和“bridges, roads and power systems”对应选项A“adequate transport facilities”；文中“keep investors away”对应题干“unappealing to investors”。
解析：题干问撒哈拉以南非洲为何对投资者缺乏吸引力。答案句明确指出“Traffic jam leads to expense and unpredictability, things that keep investors away”，即交通堵塞导致费用和不可预测性，使投资者远离，而交通堵塞源于交通设施不足（只有一条轻轨），对应选项A“It lacks adequate transport facilities”。选项B“生活费用高”偷换概念，文中说的是交通费用；选项C“人口密集”无中生有；选项D“政府腐败”文中未提。
49. In what way does the author say African cities are different?
- A. They have attracted huge numbers of farm labourers.
- B. They still rely heavily on agricultural productivity.
- C. They have developed at the expense of nature.
- D. They depend far more on foreign investment.
答案：C
答案句：In other parts of the world, increasing agricultural productivity and industrialization went together. More productive farmers meant there was a surplus that could feed cities; in turn, that created a pool of labour for factories. But African cities are different. They are too often built around consuming natural resources.
参考译文：在世界其他地区，农业生产力提高和工业化是同步进行的。更高效的农民意味着有剩余粮食可以养活城市；反过来，这为工厂创造了劳动力池。但非洲城市不同。它们往往围绕消耗自然资源而建。
定位线索：题干“African cities are different”→答案句“African cities are different”；文中“built around consuming natural resources”对应选项C“developed at the expense of nature”；文中“consuming natural resources”与选项C“at the expense of nature”同义。
解析：题干问作者说非洲城市在哪些方面不同。答案句先描述其他地区城市发展模式（农业生产力与工业化结合），然后转折“But African cities are different”，接着说明“They are too often built around consuming natural resources”，即非洲城市围绕消耗自然资源而建，对应选项C“They have developed at the expense of nature”。选项A“吸引大量农业劳动力”与原文相反，原文说非洲农业生产力低；选项B“依赖农业生产力”与原文“African agriculture is still broadly unproductive”矛盾；选项D“依赖外国投资”无中生有。
50. What might be a solution to the problems facing African cities?
- A. Lowering of apartment rent.
- B. Better education for residents.
- C. More rational overall planning.
- D. A more responsible government.
答案：D
答案句：If city leaders were more accountable to their residents, they might favour projects designed to help them more. Yet even as new roads are built, new people arrive. When a city's population grows by 5% a year, it is difficult to keep up.
参考译文：如果城市领导者对居民更加负责，他们可能会更倾向于支持旨在帮助居民的项目。然而，即使修建了新道路，新的人口也会到来。当一个城市的人口每年增长5%时，很难跟上。
定位线索：题干“solution to the problems”→答案句“If city leaders were more accountable”；文中“more accountable to their residents”对应选项D“A more responsible government”；文中“accountable”与选项D“responsible”同义。
解析：题干问非洲城市问题的可能解决方案。答案句提出“If city leaders were more accountable to their residents, they might favour projects designed to help them more”，即如果城市领导者对居民更负责，就会支持帮助居民的项目，对应选项D“A more responsible government”。选项A“降低公寓租金”无中生有，文中只提到租金高但未提降低；选项B“更好的教育”无中生有；选项C“更合理的总体规划”文中未提，且最后一句暗示人口增长快难以规划。