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.
Which of the following is most strongly supported by the information provided?
The virus that causes Lofgren’s disease cannot be transmitted to human beings by chickens.
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.
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.
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
The feed that chickens and cattle are fed is probably not the only source of the virus that causes Lofgren’s disease
我在别的帖子贴过了，转贴过来跟大家讨论一下
我认为第29题答案是B
C错，因为原题并未推出chickens are immue to the virus that causes this diease 的讯息或结论，因此跟原题无关！選C的人犯了一個嚴重的錯誤，就是自行假設！
而B对，因为原题第一句告诉我们Lofgren's disease has beenobserved frequentlyin commercially raisde cattle byt very rarely in chickens说明牛比鸡更常被发现淂了这种疾病，
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发表于 2005-9-1 11:41:00
