ChaseDream

标题: [求助]急，GWD28-29 [打印本页]

作者: happypoor88 时间: 2007-8-9 20:26
标题: [求助]急，GWD28-29

Q29:

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.

哪位NN能帮忙解释一下为什么选C不选B，我觉得选B啊。

作者: lanseb8ma 时间: 2007-8-10 16:03
B和C的主要差别在于，B是一个绝对否定（no way to determine），而题目中根本就没有提到是否需要这样一种手段——来判断chicken不发病是否跟早上市有关（印证这个推论才是作者关心的）；C是一种评价，而且是非绝对的评价（not good evidence），因为题干只是叙述了2个“可能存在联系的事实”，而且中间用"however"连接，反映出作者认为chicken不发病“可能”是由于其上市时间较早（虽然没有明示，但较之其他根本没有提及的cause，还是唯一的考虑因素），所以以不发病为理由，说明C对L病免疫是不合理的。

作者: leglas117 时间: 2009-8-3 16:35
受教了

欢迎光临 ChaseDream (https://forum.chasedream.com/)