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【单选题】
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 10Gbit/s—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 Universitys 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. 【C1】
A.
subsequently
B.
presently
C.
lately
D.
previously
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【多选题】下列关于职工薪酬的核算说法正确的是
A.
应由生产产品、提供劳务负担的职工薪酬,计入产品成本或劳务成本
B.
非正常消耗的直接生产人员和直接提供劳务人员的职工薪酬,应当在发生时确认为当期损益
C.
应当由在建工程、无形资产负担的职工薪酬,计入固定资产或无形资产成本
D.
难以确定直接对应的受益对象,应当在发生时计入当期损益
【单选题】在运输组织中属于活细胞的()。
A.
厚角组织
B.
厚壁组织
C.
导管与管胞
D.
筛管与伴胞
【简答题】叶片的结构: (1)图中具有输导作用的结构是[ ] _______,在它的内部既有运送__________的导管,还有运送__________的筛管。叶片与外界进行气体交换的门户是[ ] _______,其是由[ ] _______围成的空腔。这种细胞_______(填“含有”或“不含”)叶绿体。 (2)图中15是__________,其所属于的组织是__________。3是叶...
【单选题】地震波分为体波和面波,体波又分为纵波和横波,它们的传播速度有下列规律()。
A.
面波>纵波>横波
B.
纵波>横波>面波
C.
横波>纵波>面波
D.
纵波>面波>横波
【简答题】地震波分为横波和()。
【单选题】在机械组织中属于活细胞的()。
A.
厚角组织
B.
厚壁组织
C.
导管与管胞
D.
筛管与伴胞
【多选题】下列关于职工薪酬的核算说法正确的是( )
A.
应由生产产品、提供劳务负担的职工薪酬,计入产品成本或劳务成本
B.
非正常消耗的直接生产人员和直接提供劳务人员的职工薪酬,应当在发生时确认为当期损益
C.
应由在建工程、无形资产负担的职工薪酬,计入固定资产或无形资产成本
D.
难以确定直接对应的受益对象,应当在发生时计入当期损益
【单选题】初级卵母细胞完成第一次成熟分裂发生在
A.
原始卵泡阶段
B.
初级卵泡阶段
C.
排卵前36~48小时
D.
排卵时
【判断题】一般而言,地震波分为纵波和横波,发生地震时,横波总是先到达地表,而纵波总落后一步。()
A.
正确
B.
错误
【简答题】地震波包括体波和面波,体波分为 波和 波,面波分为 波和 波,其中波速最快的波为 波。
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