单词：ekacesium
音标：[ekeɪ'siːziəm] ；
n. 准铯(钫)
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[00:06.37]The United States has a new official clock. [00:10.95]The clock began operating late last year in the American city of Boulder,Colorado. [00:18.39]Experts say the new clock is so exact that it will neither gain nor lose so much as one secon
发表于:2018-12-26 / 阅读(69) / 评论(0)
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Youve given some thought to oxygen, carbon, uranium. But youve probably never mused about the element ytterbium, symbol Yb. A new study by scientists at the National Institute of Standards and Technology, or NIST, says that ytterbium could find a rol
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By Saqib ul-Islam Washington 12 October 2009 Amreeka's stars, pictured on the movie's promotional poster What is it like for a mother and her teenage son to settle in America? And what if they are Palestinian and their arrival coincides with the ons
发表于:2019-02-20 / 阅读(157) / 评论(0)
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