" There are no shortcuts in evolution," famed Supreme Court justice Louis Brandeis once said. He might have reconsidered those w

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问题     " There are no shortcuts in evolution," famed Supreme Court justice Louis Brandeis once said. He might have reconsidered those words if he could have foreseen the coming revolution in biotechnology, including the ability to alter genes and manipulate stem cells. These breakthroughs could bring on an age of directed reproduction and evolution in which humans will bypass the incremental process of natural selection and set off on a high-speed genetic course of their own. Some of the latest and greatest advances like pluripotent stem cells, gene targeting, and artificial chromosomes could leapfrog over evolution and let us take control of our genome, maybe even turn ourselves into a whole new species.
    Bioethicist John Harris of the University of Manchester, believes that achieving our potential "might require some deliberate changes" to our genes. He predicts that genetic engineering will eventually lead to what he calls "enhancement evolution. " Through the nuanced use of biotechnology, enhancement evolution will gradually introduce genes that improve the species, one person at a time. At that point, deliberate selection will replace natural selection as the driving force for species change. " We are not suited to survive designed as we are," Harris says. " We are hugely vulnerable to diseases, and new diseases come along all the time. It’s amazing we haven’t been entirely wiped out by one. "
    The first changes to the human genome, Harris believes, will happen within small test populations. This will allow us to assess the risks and benefits of the modifications and then decide how to proceed.
    Enhancement evolution has plenty of critics. Lanza, for one, is uneasy about giving parents the power to design their children’s genomes. What if a couple wants a world-class athlete in the family and provides those genes, but the child grows up wanting to play chess, he asks. And what if some of the modifications go seriously wrong? Who should have the final say on when and how the human genome should be changed?
    On the other hand, if technology can enable us to eliminate disease and disabilities from our children or insert genes that might make them smarter or better looking, why wouldn’t we use it? As DNA guru James Watson once said, " Evolution can be just damn cruel. " At least it is today. Tomorrow the responsibility for evolution may rest on our own shoulders—for better or for worse.  
The word "vulnerable"(Line 6, Paragraph 2)most probably means______.

选项 A、entirely wiped out
B、on the alert
C、easy to be attacked
D、getting immune

答案C

解析 语义题。根据第二段第六行对应的原文“We are not suited to survive designed as we are,”Harrissays.“We are hugely vulnerable to diseases,…It’s amazing we haven’t been entirely wiped out byone.”,可知哈里斯认为人类目前的构造不适宜生存,而词组wipe out意为“摧毁,毁灭”,人类没被疾病毁灭已是奇迹了,可见vulnerable to diseases的意思是“容易感染疾病”。因此,答案为[C]。四个选项中最易排除[D]项getting immune,意为“对……免疫”,这与原文所述恰恰相反。[B]项on the alert意为“保持警惕”,并非文章所讨论的话题,故[B]不可能吻合。[A]项entirely wiped out,几乎是文中原词,但所猜词应是说明人类当前的真实状况,而“完全灭绝”是一种假设,故排除。
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