[讨论]大全-2-20

dc

XDF-CR -section 2-19,20
Questions 19-20 are based on the following.
Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 percent of all prospective blood donors, they will still miss two-thirds of donors carrying NANB hepatitis. Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.
19. The argument above depends on which of the following assumptions?
(A) Donors carrying NANB hepatitis do not, in a large percentage of cases, carry other infections for which reliable screening tests are routinely performed.
(B) Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
(C) The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
(D) The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
(E) The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.  
20. Which of the following inferences about the conse-quences of instituting the new tests is best supported by the passage above?
(A) The incidence of new cases of NANB hepatitis is likely to go up by 10 percent.
(B) Donations made by patients specifically for their own use are likely to become less frequent.
(C) The demand for blood from blood banks is likely to fluctuate more strongly.
(D) The blood supplies available from blood banks are likely to go down.
(E) The number of prospective first-time donors is likely to go up by 5 percent.

For 20, anwser D depends on the assumption that the number of people want to donate blood does not increase and the blood usage does not decrease.
However, if we assume people catch NANB if and only if through blood transfer (however unreasonable this assumption is), then (A) can be inferred.

I know this might sound like 胡搅蛮缠，even though I do not think (A) is correct, I don't think (D) is much better. As said, it depends on the assumption that the number of people go to screening does not increase, which I don't think you can infer from the question.

So, 你怎样把握哪些additional assumption is reasonable, which are not ?

cranberry

对20题选项D是自然的推论，因为我们不须引入新的条件，只假定在和文中所说条件不变的情况下，这个推论就是合情合理的，而如果要引入新的条件，那么这个条件要么是文中给出的，要么是常识性的，而不是“假如...”这样的假设条件。

夏麦

The incidence of new cases of NANB hepatitis is likely to go up by 10 percent A有什么错啊?题目中有一个LIKELY,而且HEPATITIS 的发生很可能会上升啊.当然D也对啊.

nickt

to 夏麦：为什么会是10％捏？（有10％的供血有病毒，不能成为这原因吧）

boluomeimei

还是不明白为什么D是对的。。。怎么推出来的啊？？

B是什么意思呢？

[此贴子已经被作者于2005-9-19 10:32:22编辑过]

一起加油的夥伴

hi boluomeimei,

我覺得依照原文中所說的Therefore, about 10 percent of actual donors will still supply NANB-contaminated blood.這樣來看的話選 A 並不好,因為已經超出原文的範圍了,因為發現感染H 病的new case並不一定是有去捐血的人,所以

答案D似乎比較合乎原文的結論,希望高手來指正我的錯誤

向上爬的猪

如果每个带病的人先二包,分别给两个可怜的清白的受学病人用了,那不就出现increase by 20%的情况了吗？

况且，题中没说这种病会传染啊。如果不会传染，那不就是increase by 0% 了吗？

所以A不对

题干最能支持D，献学人少了5%学库的供学量自然少了。

sch

还是钻了牛脚尖
A是说，新的NANB病的的可能性将上升到10％。

这个完全是无中生有的无关推导。 NANB病的获得概率和血库中存在10％ NANB毒血没有必然联系！脑子晕了。。。。。


输血又不是NANB病传播的only途径，就算是唯一途径，象楼上说的，每一包毒血2人用，那么概率就会上升了。