og18题。。关于充分必要条件

18 Opponents of laws that require automobile drivers and passengers to wear seat belts argue that in a free society people have the right to take risks as long as the people do not harm others as a result of taking the risks. As a result, they conclude that it should be each person's decision whether or not to wear a seat belt.

Which of the following, if true, most seriously weakens the conclusion drawn above?

Answer: B. Automobile insurance rates for all automobile owners are higher because of the need to pay for the increased injuries or deaths of people not wearing seat belts.

请问as long as是什么条件的标志词啊？

我本来认为是必要条件，就是说后面的people do not harm others as a result of taking the risks是必要条件，削弱A推出B的唯一办法是说A推出否B （新东方老师上课讲的），那么就与答案所表达的意思：对别人造成了损害也就是否B相符。

但是这样一来就是说 如果人们有权选择乘不承担风险 推出 那么不损害他人，这样总觉得语义逻辑上不太对。应该是如果不损害他人就可以选择乘不承担风险，这样一来as long as后面的内容就变成了充分条件，那么削弱就不是A推出否B了，那么到底是什么呢？

写了这么多不知道大家看得懂嘛。。我逻辑真差。。希望高手讲解一下。。

as long as , 我认为是充分条件。

可以这么想，如果people do harm others as a result，则肯定有people do not have the right to take risks

即~B --> ~A，所以B是A的必要条件，A是B的充分条件

as long as 是充分条件，不是必要条件