单词：cesium bromide
单词：cesium 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
农业与发展
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
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