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  3. The railroad industry could not have grown as large as it did without steel. The first rails were made of iron. But iron rails w

The railroad industry could not have grown as large as it did without steel. The first rails were made of iron. But iron rails w

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问题 The railroad industry could not have grown as large as it did without steel. The first rails were made of iron. But iron rails were not strong enough to support heavy trains running at high speeds. Railroad executives wanted to replace them with steel rails because steel was ten or fifteen times stronger and lasted twenty times longer. Before the 1870’s, however, steel was too expensive to be widely used. It was made by a slow and expensive process of heating, stirring, and reheating iron ore.
    Then the inventor Henry Bessemer discovered that directing a blast of air at melted iron in a furnace would burn out the impurities that made the iron brittle (易碎的). As the air shot through the furnace, the bubbling metal would erupt in showers of sparks. When the fire cooled, the metal had been changed, or converted, to steel. The Bessemer Converter made possible the mass production of steel. Now three to five tons of iron could be changed into steel in a mater of minutes.
    Just when the demand for more and more steel developed, prospectors, discovered huge new deposits of iron ore in the Mesabi Range, a 120-mile-long region in Minnesota near Lake Superior. The Mesabi deposits were so near the surface that they could be mined with steam shovels.
Barges and steamers carded the iron ore through Lake Superior to depots (车站) on the southern shores of Lake Michigan and Lake Erie. With dizzying speed, Gary, Indiana, and Toledo, Youngstown, and Cleveland, Ohio, became major steel-manufacturing centers. Pittsburgh was the greatest steel city of all.
    Steel was the basic building material of the industrial age. Production skyrocketed from seventy-seven thousand tons in 1870 to over eleven million tons in 1900.
According to the passage, where were large deposits of iron ore uncovered?
选项 A、In Pittsburgh.
B、In the Mesabi Range.
C、Near lake Michigan.
D、Near Lake Erie.
答案B
解析 见第三段第1句；Pittsburgh(匹兹堡)是最大的炼钢中心；Lake Michigan(密歇根湖)和Lake Erie(伊利湖)南岸是装铁矿石的仓库所在地；这两个湖与Lake Superior(苏必利尔湖)、lake Huron(休伦湖)、lake Ontario(安大略湖)构成了著名的the Great Lakes(五大湖)，其中Lake Michigan全在美国境内，其余四湖为美国、加拿大共有
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