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本来想分析赞成D的，分析分析，却发现在C才是正确的
Lofgren’s disease has been observed frequently in commercially raised cattle but very rarely in chickens. Both cattle and chickens raised for meat are often fed the type of feed that transmits the virus that causes the disease. Animals infected with the virus take more than a year to develop symptoms of Lofgren’s disease, however, and chickens commercially raised for meat, unlike cattle, are generally brought to market during their first year of life.
（此段简而言之，是牛与鸡吃同样传染病毒的饲料，牛发病而鸡未发病是因为发病是在感染病毒一年后，而鸡的寿命不到一年。意指鸡也被传染了病毒但来不及发病便死了）
Which of the following is most strongly supported by the information provided?
A: The virus that causes Lofgren’s disease cannot be transmitted to human beings by chickens.
B: There is no way to determine whether a chicken is infected with the Lofgren’s disease virus before the chicken shows symptoms of the disease.
（B项认为在鸡表现出患病症状之前，无法得知鸡是否感染了病毒。据此推论，既然鸡未表现症状，凭什么说鸡就感染了病毒呢而未表现呢，显然与文章论点相悖）
C: A failure to observe Lofgren’s disease in commercial chicken populations is not good evidence that chickens are immune to the virus that causes this disease.
（此项与文章意思一致，没得病不代表有免疫，不代表没被传染。）
D: An animal that has been infected with the virus that causes Lofgren’s disease but that has not developed symptoms cannot transmit the disease to an uninfected animal of the same species.
（此项说传染了病毒但没症状的鸡不能传染病毒，本文并没有这层意思，因为对鸡本身来说就存在一个饲料感染问题，彼此之间传染与否都没关系，就是彼此传染了也来不及表现症状。）
E: The feed that chickens and cattle are fed is probably not the only source of the virus that causes Lofgren’s disease.
[此贴子已经被作者于2005-12-2 17:43:09编辑过] | 
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发表于 2005-11-2 21:31:00
