请教GWD28-Q29

freddong

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?   

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.

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.

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.

E.       The feed that chickens and cattle are fed is probably not the only source of the virus that causes Lofgren’s disease.

坛子里没搜到。答案是C？我选的B。不明白为什么~~求教。谢谢

xfi883

原文中并没有提到“有没有方法”去诊断“鸡是否感染了病毒”，所以B选项的“没有办法在鸡显示出症状前决定鸡是否感染病毒”没有依据。

路吉儿

lishihui2009

cccc

vivian0331

E为什么不对？

我的想法是，题干论述：

1) Lofgren’s disease has been observed frequently in commercially raised cattle but very rarely in chickens. (提出现象，牛多、鸡少)

2) Both cattle and chickens raised for meat are often fed the type of feed that transmits the virus that causes the disease. (牛鸡同食)

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.（鸡先上市，按理说应该比牛感染多）

通过1\2\3，我们看到一种矛盾：按常理应该鸡多牛少，为什么监测是牛多鸡少呢？

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.

我觉得C选项是对的。

但是，我觉得E选项也没有错啊：

E.    The feed that chickens and cattle are fed is probably not the only source of the virus that causes Lofgren’s disease. 解释了牛多鸡少的其他可能原因

谁能帮忙解释E?

E.    The feed that chickens and cattle are fed is probably not the only source of the virus that causes Lofgren’s disease. 解释了牛多鸡少的其他可能原因

谁能帮忙解释E?

斯咏

vote for c

ls 说的是削弱题设结论的可能性

但题目问的是support by 即结论题型

故不能出现与原文无关的答案

[此贴子已经被作者于2009/8/2 14:56:45编辑过]