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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
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
Protamine sulfate is a drug that reverses the anticoagulant effects of liver compounds such as heparin. Protamine is extracted from the sperm of salmon and other species of fish, and then made into a protamine sulfate injection which is a necessary d
世界各地新闻集锦
U.S. retail sales fell half a percent in June providing more evidence that the U.S. economic recovery will slow down in the second half of the year. But the weaker than expected consumer spending appeared to have little impact on Wall Street as inves
VOA标准英语2010年(七)月
We keep pumping carbon dioxide into the atmosphere and the earth keeps warming. Climate scientists have predicted that the consequences of unchecked warming could result in everything from catastrophic flooding to larger and more deadly hurricanes. S
英语时差8，16
First off, I'll mention that at the bottom of the sea there exist veins of zinc, iron, silver, and gold whose mining would quite certainly be feasible. 首先，我对您说，海底有锌、铁、银、金等矿藏，开发并不是不可能的事。
《海底两万里》中英双语有声读物