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  3. Could a plant virus have found a way to infect humans? It has always been assumed that plant viruses cannot infect animals, and

Could a plant virus have found a way to infect humans? It has always been assumed that plant viruses cannot infect animals, and

admin2015-07-31  45
问题     Could a plant virus have found a way to infect humans? It has always been assumed that plant viruses cannot infect animals, and vice versa, but plant viruses are known to be【C1】______in human faeces(粪便).
    Now Didier Raoult at the University of the Mediterranean in Marseille, France, and his team think a pepper virus is making people【C2】______, too. They have found RNA from the pepper mild mottle virus in the faeces of 7 percent of the 304 adults they tested. Those with the virus were more【C3】______to report fever, abdominal pain and itching(痒)than those without it, his team found.
    Not everyone is convinced, however. Because Raoult looked at many possible【C4】______, he would be expected to find a few that randomly【C5】______more common in virus-positive people, says Robert Garry, a virologist at Tulane University in New Orleans, Louisiana. Moreover, in order to enter a cell and replicate, a virus must bind to a receptor on its surface, and a plant virus would be highly unlikely to【C6】______a receptor on a human cell, says Garry.
    One possibility, Raoult says, is that the virus does not infect human cells【C7】______. Instead, the naked viral RNA may alter the【C8】______of the cells through a mechanism similar to RNA interference, in which the presence of certain RNA sequences can【C9】______genes on and off. Raoult’s team is now working to【C10】______more direct evidence that the virus does infect humans.
A)abundant F)function K)situations
B)appear G)gather L)surprisingly
C)available H)likely M)symptoms
D)capacity I)recognise N)tested
E)directly J)sick O)turn
【C3】
选项
答案H
解析 形容词辨析题。分析句子结构可知，空格所在句主语为Those with the virus，空格在系动词were和比较级标志more之后，因此应填形容词。根据句意可知，那些体内携带这些病毒的人——发烧、腹痛和瘙痒。再结合备选项可知，likely“可能的"符合题意。be likely to do意为“可能做……”。
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