In the early 1950s the researchers who produced the first clad glass optical fibers were not thinking of using them for communic

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问题         In the early 1950s the researchers who produced the first clad glass optical fibers were not thinking of using them for communications.【C1】H __________, fiber optics was already a well-established commercial technology when the famous paper by Kao and Hockham, 【C2】__________(claim) the use of low-loss optical fibers for communication, appeared in 1966.The first low-loss silica fiber was described in 【C3】__________which appeared in October of 1970.The date of this publication is sometimes 【C4】__________(cite) as the beginning of the era of fiber communication.Although this development did receive 【C5】__________(consider) attention in the research community at the time, it was far from inevitable that a major industry would evolve.
        The technological barriers appeared formidable because there were serious doubts as to 【C6】wh__________ these fiber components could ever be produced economically enough, but the market potential was very significant.【C7】__________(consequence), research and development activity expanded rapidly, and a number of important issues were 【C8】 re__________ during the early 1970s.During the middle and late 1970s, the rate of progress towards marketable products accelerated as the emphasis 【C9】__________(shift) from research to engineering.Fibers with losses 【C10】app__________ the Rayleigh limit of 2 dB/km at a wavelength of 0.8μm were produced.
        By 1980 improvement in component performance, cost, and reliability led to major commitments on the part of telephone companies.
【C1】

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答案However

解析 空格上下文的句意为:50 年代初期,那些生产出第一批复合玻璃光纤的研究员们尚未考虑将光纤应用到通信中。然而,当1966年卡奥和霍克姆发表著名论文,提出把低耗光纤应用于通讯中时,光纤已经成为一项相当成熟的商业技术了。可以看出上下文句意有转折,故根据提示字母此空应填入However。
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