Skyscrapers and Environment
In the late 1960's，many people in North America turned their attention to environmental problems，and new steel-and-glass skyscrapers were widely criticized. Ecologists pointed out that a cluster of tall buildings in a city often overburdens public transportation and parking lot capacities.
Skyscrapers are also lavish consumers，and wasters，of electric power. In one recent year，the addition of 17 million square feet of skyscraper office space in New York City raised the peak daily demand for electricity by 120，000 kilowatts-enough to supply the entire city of Albany，New York，for a day.
Glass-walled skyscrapers can be especially wasteful. The heat loss（or gain）through a wall of half-inch plate glass is more than ten times that through a typical masonry wall（砌筑墙）filled with insulation board（隔热板）.To lessen the strain on heating and air-conditioning equipment，builders of skyscrapers have begun to use double-glazed panels of glass，and reflective glasses coated with silver or gold mirror films that reduce glare as well as heat gain. However，mirror-walled skyscrapers raise the temperature of the surrounding air and affect neighboring buildings.
Skyscrapers put a severe strain on a city's sanitation facilities，too.If fully occeupied，the two World Trade Center towers in New York City would alone generate 2.25 million gallons of raw sewage each year-as much as a city the size of Stanford，Connecticut，which has a population of more than 109，000.
【第11题】11.The main purpose of the passage is to_____.
A、discuss the advantages and disadvantages of skyscrapers
B、compare skyscrapers with other modern structures
C、describe skyscrapers and their effect on the environment
D、illustrate various architectural designs of skyscrapers
【正确答案】：C
【题目解析】：通观全文，文章在说摩天大楼所引起的环境问题：浪费电能、损耗热能、产生大量废水。因此选C，文章没有提到摩天大楼的好处，因此不能选A；没有和其他现代建筑作对比，因此排除B；没有描绘各种摩天大楼的建筑设计，因此也不能选择D
