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Li-Fi, an alternative to Wi-Fi that transmits data using the spectrum of visible light, has achieved a new breakthrough, with UK

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问题     Li-Fi, an alternative to Wi-Fi that transmits data using the spectrum of visible light, has achieved a new breakthrough, with UK scientists reporting transmission speeds of lOGbitfe—more than 250 times faster than ’superfast’ broadband. The fastest speed【C1】________reported was 3Gbit/s, achieved earlier this year in Germany. Chinese researchers also claimed this month to have【C2】________a 150Mbp/s connection, but some experts were doubtful without seeing further【C3】________.
    The term Li-Fi was【C4】________by Edinburgh University’s Prof Harald Haas【C5】________the technology is also known as visible light communications (VLC). Many experts claim that Li-Fi represents the future of mobile internet【C6】________ its reduced costs and greater efficiency compared to traditional Wi-Fi. Both Wi-Fi and Li-Fi transmit data【C7】________ the electromagnetic spectrum, but【C8】________Wi-Fi utilizes radio waves, Li-Fi uses visible light. This is a【C9】________ advantage in that the visible light is far more plentiful than the radio spectrum (10,000 times more in fact) and can achieve far greater data【C10】________Li-Fi signals work by【C11】________bulbs on and off【C12】________quickly—too quickly to be noticed by the human eye. This most recent breakthrough builds upon this by using tiny micro-LED bulbs to【C13】________several lines of data in parallel. The research was carried out by the Ultra Parallel Visible Light Communications project, and funded by the Engineering and Physical Sciences Research Council.
    Existing LED light bulbs could be【C14】________to transmit Li-Fi signals with a single microchip, and the technology would also be of use in situations where radio frequencies cannot be used for fear of【C15】________with electronic circuit. And although Li-Fi bulbs would have to be kept on to transmit data, the bulbs could be【C16】________to the point that they were not visible to humans and yet still【C17】________. One draw-back is that the data receiver would have to be in sight of the transmitter-bulb as visible light does not【C18】________solid materials.
    The makers of Li-Fi note that this quality might actually be an advantage in some【C19】________making Li-Fi more【C20】________than Wi-Fi with hackers unable to access unsecured internet connections from out of sight of the transmitter.
【C7】
选项 A、by
B、with
C、upon
D、over
答案D
解析 此空格需要填入一个能与电磁波谱搭配的介词构成方式状语。D项over表示“通过……媒介”，代入句中表示“Wi -Fi和Li-Fi都是通过电磁波谱来传输数据”。A项by表示采用某种方式或手段，后面的名词一律不用定冠词the。B项with表示使用有形的工具，例如第三段transmit Li-Fi sigils with a single microchip表示“用一个微芯片来传输Li-Fi信号”，而the electromagnetic为无形之物。C项upon与over都可以表示“在……之上”，但是不能表示“通过”。
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