2012淘金英語(yǔ)專業(yè)四級(jí)聽寫 上海外國(guó)語(yǔ)大學(xué) 請(qǐng)從正文部分開始聽寫
Skyscrapers were invented in the United States. As early as the 1880s, two new technical developments made these taller buildings possible. One development was the mechanical elevator. It meant that people would not have to climb many steps to reach the upper floors of tall buildings. The development of steel building technology also helped make taller buildings possible. Many experts consider the Home Insurance Building in Chicago to be the first skyscraper. This tower was about 55 meters tall. Today this would not be considered much of a skyscraper. But at the time, this height was striking. The structure was built using a steel frame. This frame was load-bearing, meaning that the steel skeleton would support the building's weight, not its walls. Before this technology, a taller building required creating thicker stone walls to support its weight. Thick walls are extremely heavy, and allow less room for windows and light.