人教 | 高中英语词汇与阅读选修八：Unit2（附音频、双语文本）

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 bothexamples of natural clones.

Cloning has two major uses. Firstly, gardeners use it all the time to produce commercial quantities of plants. Secondly, it is valuable forresearch on new plant species and for medical research on animals. Cloning plants is straightforward while cloning animals is verycomplicated. 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 todevelop normally was very encouraging. Then came the disturbing news that Dolly had become seriously ill. Cloning scientists werecast down to find that Dolly’s illnesses were more appropriate to a much older animal. Altogether Dolly lived six and a half years, half thelength of the life of the original sheep. Sadly the samearbitrary fate affected 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 ifcorrections 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 becamecontroversial. 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 embryos needed for cloning research are difficult to obtain, newspapers wrote of evil leaders hoping to clone themselves to attain their ambitions. Religious leaders alsoraised moral questions. Governments became nervous and moreconservative. Some began to reform their legal systems andforbade 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.

声明：除特别注明原创或授权转载文章外，其他文章均源自网络，版权归原作者或平台所有。如涉权属，请后台联系删除或处理版权相关事宜。

猜您喜欢往期精选▼

合辑 |《英语语法入门》50讲视频汇总

听书 | The Little Prince（小王子）

动画 | 西游记小猪佩奇：第一季 第二季

动画 | 科学小子席德、超级飞侠

语音 | 英音发音工作室 美语教学教程

合辑 | 伊索寓言 · 英文版

合辑 | 40+英文名著 41+英文童话

资料 | 人教英语：七年级下册、八年级下册

网络资源，仅供学习交流

点击“阅读原文”开启你的学习旅程吧！