The race skywards began in America. In the late1800s, industrialization had driven urban populations and land prices up, making tall buildings increasingly cost-effective, according to Carol Willis, director of the Skyscraper Museum in New York, “The very first tall buildings were office buildings that concentrated a work force, piled one on top of the other in order to make business very efficient, ”she says.
Like all major changes in architecture, the trend was underpinned by engineering. The development of steel framework, which could be used instead of load-bearing stones, made it easier and cheaper to build tall. The coming of the elevator, meanwhile, made living on higher floors far more convenient.
Though similar in shape, today's skyscrapers (摩天大楼) look little like those built in the first half of the 20th century. This is mostly thanks to architecture's next major technological shift：the curtain wall.
Postwar developments in manufacturing meant that huge panes of glass could be produced quickly and uniformly, and glass windows soon became the front of choice for high-rises. As well as allowing for greater floor space and more natural light, glass exteriors (外部) help. buildings resist greater wind loads.
There are now 191 completed skyscrapers that are at least 300 meters tall. But that doesn't mean our cities will grow taller indefinitely. While each additional story adds sellable floor space, construction costs also rise. All buildings reach a point where adding an extra floor will cost more money than it brings.
“Every city wants to have this landmark that gives that sense of distinct culture, ”but it also needs places for people to live and work in urban settings“without the city sprawling (无序扩张), ”explains Hong Kong architect Simon Chan.
The next big challenge facing architects goes beyond height：At a time when buildings and their construction account for more than a third of the world's energy consumption and contribute about 40% of greenhouse gas emissions(排放), there are new costs to consider.
Whether it's employing more energy-efficient materials, encouraging natural air or using buildings themselves to generate solar or wind energy, reducing carbon emissions is the new frontier for many skyscraper architects.
【小题1】What does the underlined word“underpinned” in paragraph 2 probably mean?| A．Created. | B．Prepared. | C．Suggested. | D．Supported. |
| A．The development of steel framework. | B．Load-bearing stones. |
| C．The use of the elevator. | D．The curtain wall. |
| A．Our cities will grow taller definitely. |
| B．All skyscrapers are at least 300 meters tall. |
| C．Construction cost rises as the stories increase. |
| D．The profit for builders will be greater as the building becomes higher. |
| A．How to build the greenest building. | B．How to build the strongest building. |
| C．How to build the tallest building in the world. | D．How to build the most comfortable building. |
