CXD逻辑30,N哥请进!

gedn01

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.
a,b选不下来，答案是a，但我对它有质疑.more than 20%，严重受伤可能小于80的

amberdeng

B肯定不对，因为more than 20 percent of drivers and front-seat passengers in Dole County 与 severely injured 一点关系都没有。

选A，因为如果more than 20 percent were wearing seat belts at the time of their accidents，那么80 percent were not wearing seat belts at the time of their accidents就不正确了，结论也就不对了。

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.
a,b选不下来，答案是a，但我对它有质疑.more than 20%，严重受伤可能小于80的

-- by 会员 gedn01 (2010/2/20 15:11:58)