单词：cesium beam time standard
单词：cesium beam time standard 相关文章
by Jason Marshall Weve now talked about three methods for calculating average values: the mean, median, and mode (affectionately known as the three Ms). So, are we done? Is that everything we could ever want to know about interpreting average values?
数学英语
[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
美国英语听力80篇
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
Scientific American(八)月
This is the VOA Special English Health Report. Governments, businesses and other groups have promised to add three billion dollars to the fight against malaria. The promises came last week at a meeting at the United Nations in New York. The money wi
VOA慢速英语2008（十）月
Economics Report - How Gold Became the Gold Standard for Trade 经济报道 - 黄金是如何成为贸易金本位的？ This is the VOA Special English Economics Report. 这里是美国之音慢速英语经济报道。 The best example of something
2012年VOA慢速英语(四)月
If you are someone who types a furious text message, only to reconsider and edit it before hitting send, you may be in trouble. The Beam Messenger app shows everything another person is typing in a text message as they type it. This means that if you
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