The researchers, led by Hwang Woo-suk, insist they cloned an Afghan hound, only to help investigate (研究) human disease, including the possibility of cloning stem cells (干細(xì)胞) for treatment purposes.
But others immediately renewed calls for a global ban on human reproductive cloning before the technology moves any farther.
“Successful cloning of an increasing number of species confirms the general impression that it would be possible to clone any species of mammals, including humans,” said Ian Wilmut, a reproductive biologist at the University of Edinburgh who produced the first cloned mammal, Dolly the sheep, from an adult cell nearly a decade ago.
Researchers have since cloned cats, goats, cows, mice, pigs, rabbits, horses, deer, mules and gaur, a large wild ox of Southeast Asia. So far, efforts to clone a monkey or another primate with the same techniques have failed.
Uncertainties about the health and life span (壽命) of cloned animals continue to exsist; Dolly died at a young age in 2003 after developing cancer and arthritis.
Wilmut and others complimented Hwang’s achievement, reported Wednesday in the journal Nature. But they said politicians and scientists must face the larger issue — how to go on with the research without crossing the moral boundary of copying human life in the lab.
“The ability to use the technology is hopeful,” said Robert Schenken, president of the American Society for Reproductive Medicine. “However, the paper also points out that in dogs as in most species, cloning for reproductive purposes is unsafe.”
The cloned puppy was the lone success from more than 100 dogs implanted (嵌入)with more than 1,000 cloned embryos.
In a news conference in Seoul, the cloning team also condemnedthe reproductive cloning of humans as “unsafe and inefficient.” Human reproductive cloning already is banned in South Korea. Other nations, including the United States, are divided on whether to ban just human cloning or cloning of all kinds, including the production of stem cells.
【小題1】 An Afghan hound is a kind of ______.
A.cat | B.dog | C.cow | D.goat |
A.horse | B.deer | C.mules | D.gaur |
A.deer | B.mule | C.monkey | D.mouse |
A.praised | B.doubted | C.refused | D.gave up |
A.South Korea |
B.the United States |
C.both South Korea and the United States |
D.neither South Korea nor the United States |
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科目:高中英語(yǔ) 來(lái)源:皇冠優(yōu)化名題 高中英語(yǔ) 題型:050
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科目:高中英語(yǔ) 來(lái)源: 題型:053
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閱讀下面短文,從所給四個(gè)選項(xiàng)中,選出最佳答案。
Can trees talk? Yes——but not in words. Scientists have reason to believe that trees do communicate (互通信息) with each other. Not long ago, resear- chers learned some surprising things. First a willow tree(柳樹)attacked in the woods by caterpillars(毛毛蟲)changed the chemistry of its leaves and made them taste so terrible that the caterpillars got tired of the leaves and stopped eating them. Then even more astonishing, the tree sent out a special vapour — a signal causing its neighbours to change the chemistry of their own leaves and make them less tasty.
Communication, of course, doesn't need to be always in words. We can talk to each other by smiling, raising our shoulders and moving our hands. We know that birds and animals use a whole vocabulary of songs, sounds, and movements. Bees dance their signals, flying in certain patterns that tell other bees where to find nectar(花蜜)for honey. So why shouldn't trees have ways of sending messages?
1. When attacked, a willow tree will protect itself by________.
[ ]
A. changing its leaves’chemistry
B. changing its leaves’colour
C. talking to caterpillars
D. sending a special vapour
2. From the passage we know that catrpillars________.
[ ]
A. like willow trees
B. enjoy eating fallen leaves
C. feed on willow tree leaves
D. could communicate with willow trees
3. Caterpillars will stop eating willow tree leaves which________.
[ ]
A. have a chemical change and become tasteless
B. have a pleasant taste
C. are being attacked
D. are communicating
4. According to the passage, how do willow trees communicate with each other?
[ ]
A. They talk in words.
B. They send out a special vapour.
C. They wave their leaves.
D. They make special sounds.
5. According to the passage, bees communicate with each other by______.
[ ]
A. talking
B. making unusual sounds
C. singing songs
D. fly in certain patterns
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