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  3. Recently, the news has been filled with reports of the "bird flu." Asia is on a region-wide health aleft, with governments slaug

Recently, the news has been filled with reports of the "bird flu." Asia is on a region-wide health aleft, with governments slaug

admin2010-10-14  42
问题     Recently, the news has been filled with reports of the "bird flu." Asia is on a region-wide health aleft, with governments slaughtering millions of chickens to contain outbreaks of the bird flu in Thailand, Vietnam, Cambodia, South Korea, Japan and China.
    Influenza -- commonly called "flu" -- is one of the oldest and most common diseases known to man. It can also be one of the deadliest. The great "Spanish flu" pandemic(传染病)of 1918-1919 was considered the worst plague in history, killing up to 40 million people with half of the world’s population infected in only a few months.
    Influenza can also infect many different warm-blooded animals, such as birds. However, the "flu" virus usually develops different variants that are specialized for each species of animal that they infect. Cross species infections are rare.
    A flu strain called influenza A(H5N1)appears to have made a successful jump from birds to humans. The viral strain(病毒株)was first isolated from South African birds in 1961. The first known human infection occurred in a Hong Kong child in May of 1997. By the end of 1997, there were 13 confirmed cases and four deaths, all in Hong Kong. In an attempt to stop the spread of the disease, the government of Hong Kong ordered the slaughter of all chickens, ducks, geese, and domestic pigeons.
    Human infected with H5N1 so far are thought to have caught the disease from fowl and no person-to-person transmissions have been reported. The World Health Organization, however, fears that the bird flu is highly adaptable and might leap the species barrier. It says anyone exposed to the disease should be quarantined(隔离)to avoid contact with sufferers of regular human influenza.
HN1 is a flu strain ______.
选项 A、limited to Hong Kong
B、which first affected human beings in 1961
C、crossing species barriers
D、which was first isolated from American birds
答案C
解析 题干中出现的关键词H5N1特征性很强，可在第四段中找到。第一句话以及与其对应的上一段中的 cross species infections告诉我们：H5N1是从鸟类转移到人类身上的一种跨物种传染的病毒。因此C)是正确的。B)中的时间应该是1997；D)中的American birds应改为South African birds。
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