再问一道补充材料的逻辑：）

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14. A recent survey of all auto accident victims in Dole County found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that, by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severely injured if they are in an auto accident.

The conclusion above is not properly drawn unless which of the following is true?

(A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents. (B)Considerably more than 20 percent of drivers and front-seat passengers in Dole County always wear seat belts when traveling by car. (C) More drivers and front-seat passengers in the survey than rear-seat passengers were very severely injured. (D) More than half of the drivers and front-seat passengers in the survey were not wearing seat belts at the time of their accidents. (E) Most of the auto accidents reported to police in Dole County do not involve any serious injury.

答案是a。题目说的是：在对所有的受害者的调查中，80%严重受伤的司机和前座乘客没有系安全带。这说明通过系安全带，司机和前座乘客可以减少严重受伤的几率。题目让找一个这个结论的必要条件，换句话说就是“支持”。我的理解对么？完全不知道a为什么符合.

谢了.

kuuiytt

这道题我一开始也转不过来。画个图。A说了70%多的人发生事故时没有系安全带，而80%的严重事故时没有系安全带的，所以没系安全带发生严重事故的占总事故的56%多。而20%多的人发生事故时系了安全带，虽然有20%的严重事故还是系了安全带，但是系安全带发生严重事故的占总事故的4%多。所以A是给了一个范围，也就是总的事故数量，让我们可以准确比较系和不系安全带发生严重事故在总事故中所占比例。

我这样理解的，不知别人看法如何？