普通高中课程标准实验教科书 英语选修8 Unit 2 Cloning-Reading
时间：2009-09-24 03:22:05
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（单词翻译）
Cloning has always been with us and is here to stay. It is a way of making an exact copy of another animal or plant. It happens in plants when gardeners take cuttings from growing plants to make new ones. It also happens in animals when twins identical in sex and appearance are produced from the same original egg. The fact is that these are both examples of natural clones.
Cloning has two major uses. Firstly, gardeners use it all the time to produce commercial quantities of plants. Secondly1, it is valuable for research on new plant species and for medical research on animals. Cloning plants is straightforward2 while cloning animals is very complicated. It is a difficult task to undertake. Many attempts to clone mammals failed. But at last the determination and patience of the scientists paid off in 1996 with a breakthrough - the cloning of Dolly the sheep. The procedure works like this:
On the one hand, the whole scientific world followed the progress of the first successful clone, Dolly the sheep. The fact that she seemed to develop normally was very encouraging. Then came the disturbing news that Dolly had become seriously ill. Cloning scientists were cast down to find that Dolly's illnesses were more appropriate to a much older animal. Altogether Dolly lived six and a half years, half the length of the life of the original sheep. Sadly the same arbitrary fate affected3 other species, such as cloned mice. The questions that concerned all scientists were: "Would this be a major difficulty for all cloned animals? Would it happen forever? Could it be solved if corrections were made in their research procedure?"
On the other hand, Dolly's appearance raised a storm of objections and had a great impact on the media and public imagination. It became controversial. It suddenly opened everybody's eyes to the possibility of using cloning to cure serious illnesses and even to produce human beings.
Although at present human egg cells and embryos4 needed for cloning research are difficult to obtain, newspapers wrote of evil leaders hoping to clone themselves to attain5 their ambitions. Religious leaders also raised moral questions. Governments became nervous and more conservative. Some began to reform their legal systems and forbade research into human cloning, but other countries like China and the UK, continued to accumulate evidence of the abundant medical aid that cloning could provide. However, scientists still wonder whether cloning will help or harm us and where it is leading us
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