大全-2-19

dz

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.

我连原文也没有读懂！能帮我解释一下么？谢谢

mythicalman

E，说献血者里肝炎的比例，删去了5％，还剩10％献血者患肝炎。

dz

以下是引用mythicalman在2003-11-28 23:05:00的发言：
E，说献血者里肝炎的比例，删去了5％，还剩10％献血者患肝炎。

谢谢，懂了！但是答案是A

dhxy

是啊，为什么答案是A？A中的other infections 不是无关信息吗？

G-CRACKER

原文大意：血库马上就要开始屏蔽掉所有换NANB的献血者。虽然可以屏蔽掉5%的献血者，但还是会有2/3的NANB携带者检查不出来，（也就是说屏蔽掉的5%占所有携带NANB献血者的1/3，未被屏蔽掉的占总献血者的10%）。因此10%的实际献血者还是会提供携带有NANB的坏血。

答案A说相当数量的携带有NANB的献血者不会携带其他传染病，这些传染病用日常的检查测试就可以查的出来。

取非A就是相当数量的携带有NANB的献血者还携带其他传染病，这样他们也一定会被屏蔽掉，结果就不会有10%人献NANB坏血。