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  3. It’ s one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a c

It’ s one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a c

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问题         It’ s one of our common beliefs that mice are afraid of cats. Scientists have long known that even if a mouse has never seen a cat before, it is still able to detect chemical signals released from it and run away in fear. This has always been thought to be something that is hard-wired into a mouse’s brain.
        But recently Wendy Ingrain, a graduate student at the University of California, Berkeley, has challenged this common sense. She has found a way to "cure" mice of their inborn fear of cats by infecting them with a parasite, reported the science journal Nature.
        The parasite, called Toxoplasma gondii, might sound unfamiliar to you, but the shocking fact is that up to one-third of people around the world are infected by it. This parasite can cause different diseases among humans, especially pregnant women—it is linked to blindness and the death of un-born babies.
        However, the parasite’s effects on mice are unique. Ingrain and her team measured how mice reacted to a cat’s urine (尿) before and after it was infected by the parasite. They noted that normal mice stayed far away from the urine while mice that were infected with the parasite walked freely a-round the test area.
        But that’ s not all. The parasite was found to be more powerful than originally thought—even after researchers cured the mice of the infection, they no longer reacted with fear to a cat’ s smell, which could indicate that the infection has caused a permanent change in mice’s brains.
        Why does a parasite change a mouse’ s brain instead of making it sick like it does to humans?
        The answer lies in evolution. Toxoplasma gondii can only reproduce inside a cat. So the parasite had to develop a way of tricking the mice into getting eaten more easily——thus helping itself go inside a cat--by taking away mice’s sense of alarm.
Which of the follow statements is TRUE according to the passage?
选项 A、Toxoplasma gondii cause people to develop strange and deadly diseases.
B、With certain infections, the infections disease can’t be cured completely.
C、Human beings infected by Toxoplasma gondii will have permanent brain damage.
D、Toxoplasma gondii is harmful to human being, but it does no harm to mice.
答案D
解析 细节理解题。A项(这种寄生虫会使人患奇怪的、致命的疾病)，文中第二段最后一句提到，这种寄生虫会使人得不同的疾病，尤其会造成未出世的婴儿失明或胎死腹中，但并没有说导致奇怪的病，所以A项表述错误。B项(因为存在一些传染，传染性疾病不能完全被治愈)，此表述文中并没有提及。C项(被这种寄生虫感染的人的脑结构将会永久性坏死)，文中第四段最后有提到，这种感染可能对老鼠的大脑造成永久性的改变，所以此表述错误。D项(这种寄生虫对人类有害，但是对老鼠却无害)，根据文章第五段第一句可知，寄生虫能改变老鼠的大脑结构而会致使人类生病，所以此表述正确。
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