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其他国家，如中国和英国，则仍然在继续收集克隆技术有可能提供丰富的医疗救助的证据。 However, scientists still wonder whether cloning will help or harm us and where it is leading us.然而科学家们仍对克隆技术有助于人类还是有害于人类，以及克隆技术将把我们引向哪里感到困惑。
4.选修八Unit2 THE RETURN OF THE DINOSAURS?恐龙的回归？
The possibility of cloning fierce and extinct wild animals has always excited film makers. 克隆凶猛和灭绝的野生动物的可能性一直使电影制片商感到兴奋。And they are not the only ones! 然而他们并不是唯一对此感到兴奋的人。The popularity of films such as Jurassic Park, in which a scientist clones several kinds of extinct dinosaurs, proves how the idea struck a mixture of fear and excitement into people's hearts. 在《侏罗纪公园》这部影片中，有一位科学家克隆了好几种不同的绝种恐龙。类似这样的电影很受欢迎，证明了这一想法使人们感到既兴奋又恐惧。 But in fact we are a long way from being able to clone extinct animals. 但事实上，想要克隆绝种动物，我们还要很长的路程要走。 Scientists are still experimenting with cloning mammals. 科学家们现在还在进行克隆哺乳动物实验，This is because the cloning of mammals is still a new science and its story only began seriously in the 1950s as this list shows:这是因为克隆哺乳动物仍然还是一门新的科学，它是从20世纪50年代才开始进行认真研究的，如下表所示：
1950s cloning of frogs 1996 first clone of a mammal: Dolly the sheep 1970s research using the embryos of mice 2000 cow gave birth to a bison 1979 work on embryos of sheep and mice 2001 China's first cloned twin calves 1981 first experimental clones of mice 2002 first cloned cats
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1983 first experimental clones of cows 2005 first cloned dog
From time to time people suggest that extinct animals like dinosaurs, can possibly be brought back to life through cloning. 不时地会有人提议，克隆技术将有可能使地球上已经消失的动物（如恐龙）复活。 Unfortunately, with what we know now, this is either impossible or unsuitable. There are many reasons.不幸的是，据我们现在所知这是不可能的，也是不合适的。其原因有很多：
◎ The initial requirement is that you need perfect DNA (which gives information for how cells are to grow). 首先要求你有完好的DNA，以提供有关细胞将如何生长的信息。
◎ All efforts of cloning an animal will be in vain if there is not enough diversity in the group to overcome illnesses. 如果某个动物群体没有足够的多样性以战胜疾病，那么克隆这种动物的所有努力都将是无用的。 Diversity in a group means having animals with their genes arranged in different ways. 群体的多样性是指这群动物的基因要以不同的方式排列。 The advantage is that if there is a new illness some of these animals may die, but others will survive and pass on the ability to resist that disease to the next generation. 其优点是，如果发生了某种新的疾病，这类动物中的一些可能会死去，而另外一些却能存活下来，并且把这种免疫力传给下一代。 The great drawback to cloning a group of animals is that they would all have the same arrangement of genes and so might die of the same illness. Then none of them would be
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left to continue the species. 经过克隆的动物群体的最大缺点是：它们的基因排列有可能完全相同，因而它们有可能会死于同一种疾病，这样它们也可能一个也留不下来传种接代了。
◎ It would be unfair to clone any extinct animals if they were to live in a zoo. 你如果克隆出任何绝种动物，而它们必须生活在动物园里那是不公平的。 A suitable habitat would be needed for them to lead a natural life. 它们需要适当的栖息地过正常的野生生活。
Based on what we know now, you cannot clone animals that have been extinct longer than 10,000 years. 就我们现在所知，你不可能克隆那些已经绝种了一万年以上的动物。 Actually, dinosaurs disappeared 65,000,000 years ago. 事实上恐龙在6，500万年以前就已经消失了， So the chance of dinosaurs ever returning to the earth is merely a dream.所以说恐龙回归地球的可能性仅仅是个梦想罢了！
5.选修八Unit 3 THE PROBLEM OF THE SHRIKES蛇的困扰
When I called up my mother in the countryside on the telephone she was very upset. 我给住在乡下的母亲打电话的时候，她感到很心烦。 \courtyard,\“我们院子里有几条蛇，”她告诉我说， \house now and then, and they seem to have made their home here, not far from the walnut tree. Can you get rid of them please?\“蛇时不时地爬到屋子边上来。可这几条蛇似乎是在屋子附近离胡桃树不远的地方安家了。你能不能把它们赶走？” I felt very proud. 我感到很自豪， Here was a chance for .me to distinguish myself by inventing something merciful that would catch snakes but not harm them. 这回我有机会来表现一下自己了。我要发明某种仁慈的东西。既可以把蛇捉住，而又不会伤
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害它们。 I knew my parents would not like me to hurt these living creatures!我知道我的父母亲是不会让我伤害这些生物的。
The first thing I did was to see if there were any products that might help me, but there only seemed to be powders designed to kill snakes. 我所做的第一件事就是看看有没有现成的产品能帮助我。但是，看来只有一种毒杀蛇的药粉。 A new approach was clearly needed. 很明显，我得找一种新的方法了。 I set about researching the habits of snakes to find the easiest way to trap them. 于是我就着手研究蛇的习性，以便能找到最容易的方法捉住它们。Luckily these reptiles are small and that made the solution easier. 好在这些爬行动物都很小，问题比较容易解决。
Prepared with some research findings, I decided on three possible approaches: 经过一番研究准备之后，我决定采用三种可能的方法： firstly, removing their habitat; 第一，铲除蛇的栖息地；secondly, attracting them into a trap using male or female perfume or food; 第二，用男人或女人用的香水或食物把它们引进陷阱； and thirdly cooling them so that they would become sleepy and could be easily caught. 第三，降低它们的体温，使它们困乏，这样就容易把它们捉住。 I decided to use the last one. 我决定采用最后一种方法。 I bought an ice-cream maker which was made of stainless steel. Between the outside and the inside walls of the bowl there is some jelly, which freezes when cooled. 我买了一个制冰淇淋的不锈钢碗，在碗的内壁和外壁之间有些胶状物，冷却后会冻结。 I put the bowl into the fridge and waited for 24 hours. 我把这个碗放进冰箱，冷冻了24小时。At the same time I prepared some ice-cubes.与此同时，我还准备了一些冰块儿。
The next morning I got up early before the sun was hot. 第二天早晨太阳光还不太热，我就早早起床了。I placed the frozen bowl over the snakes' habitat and the
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ice-cubes on top of the bowl to keep it cool. 我把冰冻的碗放在蛇窝的上方，再把小冰块放在碗上，以使碗保持冷却状态。 Finally I covered the whole thing with a large bucket. 最后再用一个大桶把碗罩住。于是我就等着。Then I waited. After two hours I removed the bucket and the bowl. 过了两个小时我才把桶和碗一起拿开。 The snakes were less active but they were still too fast for me. 蛇不像以前那么活跃了。 They abruptly disappeared into a convenient hole in the wall. 但是对于我来说，它们行动还是太快了，突然一下子就消失在附近的墙洞里去了。 So I had to adjust my plan.于是我只得调整我的计划。
For the second attempt I froze the bowl and the ice-cubes again but placed them over the snakes' habitat in the evening, as the temperature was starting to cool.第二次试验我用的还是冰冻的碗和冰块儿，但是这次我是在夜晚气温开始变凉的时候把它们放在蛇窝的上方， Then as before, I covered the bowl with the bucket and left everything overnight. 然后用桶把碗罩住，通宵放在那儿。 Early the next morning I returned to see the result. 第二天一早我就去看结果。This time with great caution I bent down to examine the snakes and I found them very sleepy. 这一次我蹲下去检查的时候，发现蛇都是睡意浓浓的。 But once picked up, they tried to bite me. 但是一把它们提起来，它们就要咬我。 As they were poisonous snakes, I clearly needed to improve my design again.因为它们都是毒蛇，所以很显然我还得改进我的捕蛇方案。 My third attempt repeated the second procedure. 第三次试验重复了第二次的程序，The next morning I carried in my hand a small net used for catching fish. This was in the expectation that the snakes would bite again. 第二天早晨我的手里拿了一个捕鱼的小网，这是因为我预料蛇还会再咬人。But monitored carefully, the snakes proved to be no trouble and all went according to plan. 经过仔细的监视，证明这些蛇不会惹
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