GRE阅读练习：法医动物学保护大象刻不容缓.docxVIP

Word文档下载后（可任意编辑） 第 第 PAGE 1 页 共 NUMPAGES 1 页 GRE阅读练习：法医动物学保护大象刻不容缓 GRE阅读训练：GRE阅读练习：法医动物学保护大象刻不容缓 GRE考试精品课程指导  FEW megafauna are more charismatic than elephants, and that charisma gives them political clout.  在大型动物里，没有几种动物可以匹敌大象的魅力，这种魅力让大象很有政治影响。  For example, Barack Obama used the Tanzanian leg of his tour of Africa to announce an executive order intended to give teeth to Americas obligation, as a party to the Convention on International Trade in Endangered Species, to prevent the smuggling of poached ivory.  比如说奥巴马总统在非洲行程中的坦桑尼亚站宣布了一项行政命令，该命令旨在通过强制实施有效手段来更好地履行美国《濒危野生动植物种国际贸易公约》的一员防止偷运偷猎象牙的义务。  The rules on trading ivory, though, are hard to enforce, for if it comes from an animal killed before 1990 such trade is legal.  但是，针对象牙贸易的规定很难实行，因为如果象牙来自的大象是在1990年之前被杀的，那么这种贸易是合法的。  Not surprisingly, a cottage industry in making ivory look older than it is has grown up.  因此，让象牙看起来比实际年代更久的家庭手工业的发展壮大就并不奇怪了。  But a paper published in the Proceedings of the National Academy of Sciences, by Kevin Uno of the University of Utah and his colleagues, may deal with that.  犹他大学的Kevin Uno和他的同事发表在《美国国家科学院院刊》上的一篇论文可以解决这个问题。  For Dr Uno has worked out how to use one of sciences less glorious episodes, the atmospheric testing of nuclear weapons, to work out exactly how old a piece of ivory really is.  因为Uno博士研究出了如何利用科学不甚光彩的一段—核武器大气层实验，来算出一节象牙的真实年代是多少。  Dr Unos method uses the ivorys carbon-14 content in a way that was not previously employed.  博士Uno的方法用到了象牙的碳-14含量，他利用碳-14含量的方式从来没人用过。  What radiochemists call 14C forms naturally in the atmosphere by the action of cosmic rays on nitrogen atoms.  被放射化学家称作碳-14的物质是宇宙射线撞击空气中的氮原子而在大气中自然形成的，  It has a half-life of 5,730 years, which makes it ideal for dating objects pertinent to human history, and it can do so to within a few decades of their true age—which is great for archaeology.  其半衰期约为5,730年，这让其十分适合测量与人类历史有关事物的年代，其测量误差不超过其真实年代前后几十年。  It is not, though, much