从原文怎么可能得出这答案？

fuzhouguy

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.

Which of the following inferences about the consequences of instituting the new test is best wupported 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.

correct choice: d

selinataki

 这里有两个概念要先搞清楚：

prospective blood donors 意为预期的血液捐献者

actual donors 意为实际的血液捐献者（已在血库捐献者名单中的）

文章说，即使预期的血液捐献者中有95%通过了筛选测试，血库仍然缺少三分之二的血液捐献者，所以还需要10%的已在血库list中的血液捐献者继续提供血液，这说明10%的实际捐献者相当于短缺的三分之二新捐献者，血液捐献者越来越少了，其结果当然是血库中可提供的血液量下降了。

fuzhouguy

哦，是这意思，原文我根本就没看懂。谢谢。

focusspeed

我觉得原文意思不是这样的：

文章说，即使预期的血液捐献者中有95%通过了筛选测试，血库仍然缺少三分之二的血液捐献者，所以还需要10%的已在血库list中的血液捐献者继续提供血液，这说明10%的实际捐献者相当于短缺的三分之二新捐献者，血液捐献者越来越少了，其结果当然是血库中可提供的血液量下降了。