A recent survey of all auto accident victims in Dole County found that, of the severely injured drivers and fron -seat passengers, 80% 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 severly injured if they are in an auto accident. The conclusion above is not properly drawn unless which of the following is true? 这道题的答案是:A) Of all the drivers and front-seat passengers in the survey, more than 20% were wearing seat belts at the time of their accidents. 请问为什么? |