[求助]陈向东归纳20

amo

    

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.

20.         Which of the following inferences about the consequences 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.（D）

(E) The number of prospective first-time donors is likely to go up by 5 percent.fficeffice" />

为什么D会是答案，靠排除法确实能得出D是答案，但是D又是怎样从逻辑的角度考虑的呢？

weiyu

因为dequalify了5%合格的