托福 新托福 59 - Building Materials
题目
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6.According to paragraph 2, how does steel compare with other forms of iron?
  • A.It is the most widely available because it is the easiest to produce
  • B.It is the hardest because it contains the least carbon
  • C.It is the easiest to shape because it contains the fewest impurities
  • D.It is the most useful because it is both strong and flexible.
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    阅读原文 中文译文

    It is difficult to exaggerate the radical change that the new industrial world of the nineteenth century brought to architectural materials Since the beginning of architectural history, the same basic substances had been employed. They were provided directly by nature and used in their natural or near-natural state, only cut, shaped, and dried into the functional forms of timbers, stone blocks, and clay bricks. The exceptions were lime mortar and Roman concrete. Metals, which had the tensile strength that masonry materials lacked, were employed in minor and supplementary ways Bronze was expensive as well as brittle Iron, the structurally more important metal, was available in limited quantities and uneven quality, and was too easily converted to rust by the elements. It was, therefore, restricted in use to things such as tie-rods and chains, and, along with bronze, to masonry clamps and decoration. Prior to the nineteenth century, the structural presence of iron in architecture was scarcely noticeable.

    The Industrial Revolution changed all that Iron materials became available in such large quant巾es that they could play far more than a minor architectural role In 1800, the world production of iron stood at 825,000 tons, by 1830 it was 1,825.000 tons, and nearly 40,000,000 in 1900-an increase of almost SO-fold over the century. The growth was not only in quantity, but quality as well. Iron, found bountifully in Earth' s crust as an oxide, is a material of almost protean variability. It is not simply pure or impure, but can be made hard or soft, brittle or ductile, strong or weak. These qualities depend on carbon content, freedom from impurities (slag), and heating and cooling treatments of the refined metal. Traditionally, three versions existed: cast iron, wrought iron, and steel. Cast iron is the, crudest form, containing the most impurities and thus being extremely brittle. Wrought iron, because it includes almost no carbon, is highly malleable (hence its name), but also comparatively soft. The optimum material is steel, which incorporates a restricted amount of carbon for hardness but is otherwise free of impurities, giving it great strength, and which, as a result of tempering treatments, is also malleable.

    Cast and wrought iron came into prodigious manufacture in the early and mid-nineteenth century as a result of rapid growth in demand, new means to transport materials, and more efficient iron-founding techniques. But the mass production of steel required further technological innovations to rid the metal of weakening impurities and to control more perfectly the amount of carbon added Such advances were made with the Bessemer process (put into use in 1860) and the open-hearth process of 1864, scient巾c iron metallurgy in the last third of the century perfected these techniques.

    A significant but little-known fact is that the mam form of increased steel production was technically not steel but a kind of wrought iron. It lacked a crucial property of true steel-its hardening power-yet it differed from the older forms of wrought iron because it was free from the weakening presence of slag, at the same time being malleable (unlike cast iron). It was called steel only because the name carried the status of a high-quality and high-priced product.

    Another alternative new building substance was concrete, composed of an aggregate of broken stone, gravel, or other small chunks of hard matter embedded in a matrix of lime, sand, and water First used in Roman times, its modern revival depended on the invention of portland cement in 1824, a substance of many times greater strength, durability, and fire resistance than ancient lime cement Mass-produced concrete began to come into widespread use in the 1850s and 1860s, in the construction of the sewers of Paris, for example. However, even with portland cement, the use of concrete was still severely restricted by its low tensile strength, but the remedy was at hand in the newly available iron and steel; their properties complemented those of concrete. The latter material was cheap, easily molded into large structural forms with great compressive but little tensile strength. Iron and steel, on the other hand were expensive, difficult to shape, yet endowed with extreme tensile strength and easily procurable in the simple form of long, thin bars.

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    最新提问
    • wx_6697
      觉得B C 意思一样,不知道选哪个
    • wx_5576
      这道题C为什么对,E为什么不对?
    • wx_5576
      B为什么不能选啊?
    • wx_6697
      TPO30 passage 2 Q5我选的 D,不明白为啥不对?
    • wx_6697
      鑫哥,TPO6passage3Q5 答案是给错了吗?好多人都选A
    • wx_6697
      这题也很容易选错选成了D
    • wx_6697
      这道题A为什么错了
    • 芊儿
      为什么这道题不选c??a中的variety不是应该对应文中的differentiating 吗??求解!
    • wx_1000
      这道题不选E是因为太细节了吗
    • 王金阁
      这个题为什么不选C啊。。。
    • 芊儿
      这道题的D选项不是和文中的better able to reproduce in open settings相对应么??
    • 风荨火
      有大佬解释一下这个为啥选D嘛?
    • 以沫
      请问这个D 在哪里提现?为什么D错?
    • 芊儿
      第六题 的C选择为什么不对,感觉A是明显驳斥啊...
    • wx_6697
      鑫哥,这道题D是从哪里看出来的
    • wx_6697
      这题选的A,根据是Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.想问鑫哥为啥不选A
    • wx_6697
      这题我选的是C依据是into a new habitat outside of its natural range, it may adapt to the new environment and leave its enemies behind.C为啥错了呢?鑫哥
    • wx_8861
      F选项的weather-related destruction在哪里体现了呢?原文最后一段的开头Among the costs里的costs是不是打错了?应该是coast?
    • wx_6697
      求问这道题B为啥不选,原文依据:viable seeds of pioneer species can be found in large numbers on some forest floors.
    • 与托福的斗争史
      与托福的斗争史 去解答 去解答
      这题为什么选C?
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B哪里错了
    • 小雨淅沥哗啦的下
      小雨淅沥哗啦的下 去解答 去解答
      B为啥不对
    • 李浩然
      B选项错误,是因为残缺么?
    • wx_100
      请问在做题的时候如何排除c呢。看了答案,感觉是该选a的,但是当时做题脑子一热,就特别钟爱c,也没看其他选项。。求敲醒。。
    • wx xxxxx
      请问鑫哥,这段开头有写As one pesticide replaces another为什么不是对应a new pesticide is developed?
    • wx_7695
      鑫哥,从哪里看出来这个masks 不是use呀,原文说了wear呀
    • haiyuqiao
      @鑫哥,这题the damage will continue 不应该对应前面的 the target species evolves resistance to it,然后As one pesticide replaces another,不应该是结束了time cycle 吗
    • wx_2065
      鑫哥,想知道E错在哪里?
    • wx_7695
      鑫哥,B选项 cannot extended to earlier geological periods. 原文说的意思是后来的进化无法估计吧
    • wx_2163
      B为什么不选
    • wx_7780
      鑫哥,这个哪里看不use了。BD是修饰错,C是无中生有,怎么能直接选出A?
    • 100
      看到第一句话,以为是中心句就选了A... 为什么不能选A呢
    • 100
      为什么选b?
    • gu33
      请问下 这里选D的原因是 因为 evolutionary approach 对应着 原文的 Rates of evolution 嘛? 这里我选了C。。不是很懂 插入句和 D的关系 求解答
    • 我是啦啦啦
      我是啦啦啦 去解答 去解答
      这个题A哪里错了?是因为主语不对吗?这个C比A多一步推理啊
    • haiyuqiao
      鑫哥,D选项里的19世纪出现了很多假设,原文中并没有提到啊
    • wx_7060
      为什么选a 呢。我觉得a是细节。F哪错了?
    • wx_1105
      我想问一下,这道题为什么不能选A呢?
    • wx_8122
      D为什么不选
    • wx_1655
      f选项哪里说了
    • chaulaw
      鑫哥,原文是below经济损害水平,D是一触发经济损害就用,这也对吗?
    • chaulaw
      interclan婚姻是对的吗?不是只在自己的family结婚扩大家族吗?
    • wx_6697
      鑫哥,这道题答案是不是错了,好多人选D 我也选的D求解答
    • wx_6697
      这道题应该是一道易错题,每个选项的都有,然而我选的A错了,求解
    • wx_6697
      鑫哥,这题的C是怎么得到的?B也没有找到啊?难道不是应该选B
    • wx_6697
      鑫哥,还有这个,好多人选A答案是不是错了
    • wx_6697
      求问D是从哪里得出来的,我选的B呀哎呀
    • wx_4185
      it is difficult to say how far they were intended to be portraits rather than generalized images 这句话怎么理解呢
    • 此楠楠
      请问下这个插入题怎么选的呢?
    • 此楠楠
      求鑫哥讲解下A选项。。。 Even though in error, Joly’s calculations clearly supported those geologists who insisted on an age for Earth far in excess of a few million years.