高中英語 學(xué)英語,練聽力,上聽力課堂! 注冊 登錄
> 高中英語 > 高中英語教材 > 普通高中課程標(biāo)準(zhǔn)實驗教科書英語選修高二下 >  第25篇

普通高中課程標(biāo)準(zhǔn)實驗教科書英語選修高二下選修8 Unit 2 Cloning-Reading

所屬教程:普通高中課程標(biāo)準(zhǔn)實驗教科書英語選修高二下

瀏覽:

手機(jī)版
掃描二維碼方便學(xué)習(xí)和分享
https://online2.tingclass.net/lesson/shi0529/0001/1695/5gyy(rj)x80009802k1.mp3
https://image.tingclass.net/statics/js/2012

            CLONING: WHERE IS IT LEADING US?

        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. Secondly, it is valuable for research on new plant species and for medical research on animals. Cloning plants is straightforward 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 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 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 embryos needed for cloning research are difficult to obtain, newspapers wrote of evil leaders hoping to clone themselves to attain 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.

用戶搜索

瘋狂英語 英語語法 新概念英語 走遍美國 四級聽力 英語音標(biāo) 英語入門 發(fā)音 美語 四級 新東方 七年級 賴世雄 zero是什么意思上海市福建中路195弄小區(qū)英語學(xué)習(xí)交流群

網(wǎng)站推薦

英語翻譯英語應(yīng)急口語8000句聽歌學(xué)英語英語學(xué)習(xí)方法

  • 頻道推薦
  • |
  • 全站推薦
  • 推薦下載
  • 網(wǎng)站推薦