单词：prescriptive rules
单词：prescriptive rules 相关文章
This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute. Beauty is only skin deep. And the beauty of shiny white teeth is even less deep. Because a new study shows that fluoride forms a thinner protective shiel
Scientific American(十二)月
07 牙病的预防与治疗 DATE=2-27-01 TITLE=SCIENCE IN THE NEWS #2113 - (1)Dental Health BYLINE=Nancy Steinbach VOICE ONE: This is Sarah Long. VOICE TWO: And this is Bob Doughty with Science in the
科技之光
[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
A cluster of villages in China's Guizhou province has been plagued by an outbreak of disease that damages teeth and bones. Now, a new study by Chinese and American researchers puts the blame on polluted coal burned in home fireplaces. In small quanti
VOA标准英语2010年(十)月
今天我们要学的词是 fluoride. Fluoride 氟化物。The U.S. government is lowering the recommended amount of fluoride added to drinking water for the first time in more than 50 years. 美国政府50多年来首次降低饮用水建议添加的氟
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