[求助]陈向东归纳7

7 Forty-five percent of all blood donated in the United States is type O. Type O blood is essential for emergencies where there is no time for determining the blood type if victims because type O blood can be used for everyone. Type O blood is unique in that it is compatible with blood of all types: any recipient, regardless of blood type, can be given it. But preciously because of this special usefulness, type O blood is chronically in short supply.

If the statements in the passage above are true, which of the following must also be true?

(A)         The special usefulness of type O blood lies in the fact that it matches the blood type of most people.

(D) Any decision to give blood of any type other than O needs to be based on knowledge of the recipient’s blood type.

答案：D

我认为A就是原文意思的改写，Type O blood is unique in that it is compatible with blood of all types: any recipient, regardless of blood type, can be given it.     但为什么A不是答案呢？