迷惑－请教，请教

x4444

5. 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.

为什么A是正确的，如果more than 20％没有安全带＋80％有的，岂不是超过100％了。


请教解释！！ 谢谢

x4444

nobody saw...... support by myself. look forward somebody reply to give me answer.

x4444

so sad....... where is NN. Pls ......

mindfree

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