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科学美国人60秒 SSS 2016-1-1
Every winter some twenty million tons of salt are dumped on America's road.That sodium chloride melts the ice, so it prevents its formatin, helping to prevent accidents. But road salt has its downside. This is not very economical because salt is main
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科学美国人60秒 SSS 2016-1-4
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科学美国人60秒 SSS 2016-1-5
After Connecticut passed a law requiring gun background checks and gun safety courses, gun deaths decreased by forty percent. Forty percent. Prsident Obama today. In his announcement that he would take executive action to require more gun sellers to
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科学美国人60秒 SSS 2016-1-6
In 1988, the US government instituted a ban on federal funding on Needle Exchange Programs for peole inject Street Drugs.Here is a quote from the article in the July 1998 issue of Scientific American on HIV prevention.Access to clean needles can help
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科学美国人60秒 SSS 2016-1-7
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-8
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-11
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-12
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-13
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-14
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-15
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-18
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-19
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-20
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
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科学美国人60秒 SSS 2016-1-21
Sorry,there is not text temporarily, Please help tingroom to look for it! 如果您能找到更好的听力原文，请发贴到 听力原文收集区 ，您将会获得10到30积分的奖励! Thank you！
