Researchers at Yale, Texas A&M and Boston University predict that by 2030 urban areas will expand by more than 463,000 square miles, or l．2 million square kilometers． That is equal to 20,000 American football fields becoming urban every day for the first three decades of this century．
The growth in urban areas will go with the construction of roads and buildings, water and sanitation facilities, and energy and transport systems that will transform land cover and cities globally． Recent estimates suggest that between $25 trillion（万亿） and $30 trillion will be spent on infrastructure（基础设施） worldwide by 2030, with $100 billion a year in China alone．
"Considering the long life and near unavoidability of infrastructure investments, it will be critical for current urbanization-related policies to consider their lasting impacts," said Karen Seto, lead author of the study． "We have a huge opportunity to shape how cities develop and their environmental impacts．"
Nearly half of the increase in high-probability ----defined as greater than 75 percent ---- urban expansion is forecasted to occur in Asia, with China and India absorbing 55 percent of the regional total． In China, urban- expansion is expected to create a l,l00-mile coastal urban corridor from Hangzhou to Shenyang． In India, urban expansion will be gathered around seven state capital cities, with large areas of low-probability growth forecasted for the Himalaya region where many small villages and towns currently exist．
Africa's urban land cover will grow the fastest, at 590 percent above the 2000 level of 16,000 square miles． Urban expansion win be concentrated in that continent's five regions: the Nile River in Egypt; the coast of West Africa on the Gulf of Guinea; the northern shores of Lake Victoria in Kenya and Uganda and extending into Rwanda and Burundi; the Kano region in northern Nigeria; and greater Addis Ababa, Ethiopia．
"Urban expansion is concentrated in． only a few areas where there are large cities and industry," said Seto． "From the northern shore of Lake Victoria down to Rwanda is also a major hotspot of urban expansion．"
In North America, where 78 percent of the total population lives in urban areas, urban land cover will nearly double by 96,000 square miles by 2030．The study also forecasts that 48 of the 221 countries in the study will experience insignificant amounts of urban expansion． "
小题1:As for China, the expansion of urban area means ．
A．$ 100 billion will be spent on infrastructure a year
B．creating a coastal urban corridor from Hangzhou to Qingdao
C．it will become the fastest developing country in the next decade
D．it will make up 55% of the increase in urban expansion in Asia小题2:According to the passage infrastructure doesn't include ．
A．construction of roads
B．sanitation facilities
C．energy systems
D．land cover transformation小题3:In paragraph three the underlined word “their lasting impacts” refers to the impacts of .
A．the development of cities
B．urbanization-related policies
C．infrastructure in vestments
D．China’s expansion of urban area小题4:The best title for this passage should be .
A．The limitation of urban expansion
B．More investment on infrastructure
C．The fast development of the third world
D．The future urban expansion of the world
，如图所示。不考虑透明物质的吸收和外表面的反射，试求该透明物质的折射率n 。