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This is Scientific American's 60-Second Science. I'm Karen Hopkin. Thisll just take a minute. Any school kid can tell you that comets are made of ice. That frozen water burning off is what gives comets their characteristic tails. But asteroids were g
Scientific American(四)月
This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute. If we want to learn more about our planet and other planets in the universe, we can get some help from stars that are long dead and gone. Thats what U.
Scientific American(一)月
Jimmy lives on the second floor of a six-unit apartment building. His front door has two locks -- a security deadbolt, and a regular door handle lock. The front door also has a peephole -- a tiny piece of glass through which Jimmy can look out his do
365个英语简短小故事
By Gary Thomas Washington 21 February 2007 As another U.N. deadline on Iran's nuclear program passed, Tehran continued to send signals of both defiance and compromise. Meanwhile, the United States and its allies on the nuclear issue remain steadfast
2007年VOA标准英语（二月）
LOS ANGELES, June 24 (Xinhua) -- Near-Earth asteroid 2011 MD will whip past Earth on June 27, but will not pose any threat, NASA's Jet Propulsion Laboratory (JPL) said on Friday. The asteroid will pass only 12,000 kilometers (7,500 miles) above the E
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BEIJING, June 28 (Xinhuanet) -- A truck-sized asteroid passed over the Atlantic Ocean within 7,500 miles of the Earth on Monday, according to NASA's Jet Propulsion Laboratory. The space rock, called asteroid 2011 MD, is the second space rock to zip e
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