Citizensof Parktown are worried by the increased frequency of serious crimes committedby local teenagers. In response, thecity government has instituted a series of measures designed to keep teenagersat home in the late evening. Even if themeasures succeed in keeping teenagers at home, however, they are unlikely toaffect the problem that concerns citizens, since most crimes committed by localteenagers take place between 3 p.m. and 6 p.m. Whichof the following, if true, most substantially weakens the argument? A.Similar measures adopted in other places have failed to reduce the number ofteenagers on the streets in the late evening. B.The crimes committed by teenagers in the afternoon are mostly small thefts andinconsequential vandalism. C.Teenagers are much less likely to commit serious crimes when they are at homethan when they are not at home. D.Any decrease in the need for police patrols in the late evening would not meanthat there could be more intensive patrolling in the afternoon. E.The schools in Parktown have introduced a number of after-school programs thatwill be available to teenagers until 6 p.m. on weekday afternoons. 不明白B选项如何削弱原文结论？作者: sdcar2010 时间: 2011-2-24 20:35
The first sentence says "Citizensof Parktown are worried by the increased frequency of serious crimes committedby local teenagers." Note the modifier SERIOUS.
If B is right, the argument falls apart because the petty crimes are not concerns of the citizens and petty crimes happens between 3 pm and 6 pm.