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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

admin2022-01-13  2
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 facces 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) recognize      N) tested
    E) directly       J) sick           O) turn
【C9】
选项
答案O
解析 动词辨析题。由空格前的情态动词can可知，空格所在分句缺少谓语，因此应填动词原形，且能与后面的on and off搭配。结合选项可知，turn“转动”符合题意，表示在此过程中，某些核糖核酸序列的出现能够打开和关闭基因，故为答案。
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