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标题: GMAT-28-29请教求解思路 [打印本页]

作者: sv2000 时间: 2005-11-11 14:42
标题: GMAT-28-29请教求解思路

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.

作者: yangsh 时间: 2005-11-11 15:03

题目，鸡和牛都应该得病，但牛经常发现，而鸡少见。得这个病的动物一般1年后才出现病症。而鸡是1岁前就到市场上了。

问推出，现在没有发现几有毛病不能说他有免疫能力。

作者: sv2000 时间: 2005-11-12 11:07
谢谢

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