单词：cesium mercuric bromide
单词：cesium mercuric bromide 相关文章
[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
AGRICULTURE REPORT - Restrictions on Methyl Bromide By Mario Ritter Broadcast: Tuesday, March 16, 2004 This is Steve Ember with the VOA Special English Agriculture Report. Graphic Image Some chemicals
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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 Caty Weaver Broadcast: September 12, 2003 This is Bob Doughty with the VOA Special English Environment Report. Scientists in the United States have reported some good news about the 1)ozone in the
VOA2003（下）-环境与健康
AGRICULTURE REPORT - Cover Crops By Mario Ritter Broadcast: Tuesday, March 23, 2004 This is Steve Ember with the VOA Special English Agriculture Report. The idea to grow a crop that improves the land
农业与发展