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  3. Steel is valued for its reliability, but not when it gets cold. Most forms of

Steel is valued for its reliability, but not when it gets cold. Most forms of

游客2023-08-08  6
问题    Steel is valued for its reliability, but not when it gets cold. Most forms of steel【C1】______become brittle (脆的) at temperatures below about -25℃ unless they are mixed with other metals. Now, though, a novel type of steel has been developed that resists【C2】______at much lower temperatures, while retaining its strength and toughness—without the need for expensive【C3】______.
   Steel’s fragility at low temperatures first became a major concern during the Second World War. After German U-boats torpedoed (用鱼雷攻击) numerous British ships, a 2,700-strong fleet of cheap- and-cheerful "Liberty ships" was introduced to replace the lost vessels, providing a lifeline for the【C4】______British. But the steel shells of hundreds of the ships【C5】______in the icy north Atlantic, and 12 broke in half and sank.
   Brittleness remains a problem when building steel structures in cold conditions, such as oil rigs in the Arctic. So scientists have【C6】______to find a solution by mixing it with expensive metals such as nickel.
   Yuuji Kimura and colleagues in Japan tried a more physical【C7】______. Rather than adding other metals, they developed a complex mechanical process involving repeated heating and very severe mechanical deformation, known as tempforming.
   The resulting steel appears to achieve a combination of strength and toughness that is【C8】______to that of modern steels that are very rich in alloy content and, therefore, very expensive.
   Kimura’s team intends to use its tempformed steel to make ultra-high strength parts, such as bolts. They hope to reduce both the number of【C9】______needed in a construction job and their weight—by replacing solid supports with【C10】______tubes, for example. This could reduce the amount of steel needed to make everything from automobiles to buildings and bridges.
   A) abruptly I) cracked
   B) additives J) fractures
   C) approach K) hollow
   D) ardently L) relevant
   E) besieged M) reshuffled
   F) channel N) strived
   G) comparable O) violent
   H) components [br] 【C6】
选项
答案 N
解析 动词辨析题。空格所在句是一个现在完成时态的句子。空格前面是助动词have，空格后面是to引导的动词不定式，因此，空格处应填入动词过去分词形式，构成完成时态，且该动词能与不定式结构搭配使用。上文提到，在寒冷条件下建造钢结构时，钢的脆性仍然是一个问题。下文提到，木村勇次及其同事研发出了新型的钢材。因此，此处是说科学家们一直在寻找解决钢的易碎缺陷的方案，空格处应填入一个表示“努力”或“致力于"之类意思的动词。动词N)strived“努力；奋斗；抗争”符合要求，故为答案。备选的其他动词过去分词均与此处要表达的“努力”或“致力于”意思不符，均可排除。
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