- UID
- 400870
- 在线时间
- 小时
- 注册时间
- 2008-11-30
- 最后登录
- 1970-1-1
- 主题
- 帖子
- 性别
- 保密
|
A chemical company claims that, since only one of 520 rats that were given high doses of a new artificial sweetener developed cancer while all the others remained healthy, the sweetener is not carcinogenic for human beings and ought to be approved for human consumption.
Which of the following, if true, most strongly supports the chemical company’s claim?
(A) Chemicals that are carcinogenic for rats are usually also carcinogenic for other animals, such as guinea pigs, used in experiments.
(B) The spontaneous incidence of cancer in this particular strain of rat is approximately one in 540.
(C) Tests conducted on a certain strain of mouse show that, of 500 mice given a dose of sweetener similar to that given the rats, 53 developed cancer.
(D) Certain chemicals that are carcinogenic for human beings have been shown not to be carcinogenic for rats.
(E) The average lifespan of the strain of rat used in the experiment is 2 years; the chemical company terminated the experiment when the rats were 13 months old.
答案：选B
疑问：实验中的发病率为1/520 大于 自然发病率1/540，不是正好说明sweetener 增大了致癌率吗？不是削弱结论吗？ |
|
京公网安备11010202008513号 京ICP证101109号 京ICP备12012021号
发表于 2011-10-10 09:08:05
收藏
收藏
