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题库 / Prep2008E1-CR-77
Citizens of Parktown are worried by the increased frequency of serious crimes committed by local teenagers. In response, the city government has instituted a series of measures designed to keep teenagers at home in the late evening. Even if the measures succeed in keeping teenagers at home, however, they are unlikely to affect the problem that concerns citizens, since most crimes committed by local teenagers take place between 3 p.m. and 6 p.m.
Which of the following, if true, most substantially weakens the argument?
Similar measures adopted in other places have failed to reduce the number of teenagers on the streets in the late evening.
The crimes committed by teenagers in the afternoon are mostly small thefts and inconsequential vandalism.
Teenagers are much less likely to commit serious crimes when they are at home than when they are not at home.
Any decrease in the need for police patrols in the late evening would not mean that there could be more intensive patrolling in the afternoon.
The schools in Parktown have introduced a number of after-school programs that will be available to teenagers until 6 p.m. on weekday afternoons.
情景：未成年人的严重犯罪是很可怕的。因此，Parktown政府想了各种方法让青少年们在晚上呆在家里。但是，由于大部分的犯罪是在下午发生的，所以就算青少年们晚上呆在家里也是没有用的。
推理：
前提：大部分的犯罪在下午发生
结论：让青少年在晚上呆在家里是没法减少严重犯罪的频率的
答案预估：
真正的必要条件应该是：大部分的“严重犯罪”在下午发生
选项分析：
A选项：其他地方用同样的防止青少年晚上外出的方法都无法令晚上外出的青少年数量减少。本选项不能反驳结论。
B选项：Correct. 大部分青少年在下午时间犯的罪都是一些诸如小偷小摸和后果不严重破坏公务等罪。如果下午时间都是小偷小摸，而晚上的时间都是严重犯罪的话，那么，让青少年晚上呆在家里就是有意义的，至少可以减少严重犯罪的可能。
C选项：青少年在家中比不在家中有更低的可能性严重犯罪。本选项和结论无关。
D选项：任何在晚上对于巡警的需求的降低并不表明在下午可以加强巡逻。本选项不能反驳结论。
E选项：Parktown的学校在周末组织了很多直到下午6点的课外项目。这个选项是试图反驳前提，也就是3点到6点，学校一般都可以组织活动。请记住，如果想靠反驳前提而削弱文段，必须明确的直接反驳，而不是“削弱”前提。
比较迷惑的是原文并没有讲到中午是小犯罪，晚上就是严重犯罪。
B选项的关键在于攻击了since的内容 —— 有效weaken
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