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CR 铅中毒
In Arumville, among those young children with elevated levels of lead in their blood, few live in houses containing lead-based paint, but many live in areas where vehicular traffic is heavy. These children's elevated blood-lead levels probably result from lead added to gasoline, since, although gasoline sold in and around Arumville has been lead-free since 1990, lead from vehicle exhaust remains in the soil for many years.
Which of the following, if true, most strengthens the argument?
Sales of lead-based paint for use in homes was banned in Arumville in 1977.
Vehicle traffic in most residential areas of Arumville is heavier today than it was twenty years ago.
Some lead in the soil comes from deteriorating lead-based paint on the exteriors of buildings.
In Arumville, children's blood-lead levels typically rise during the warm summer months when children frequently play outdoors but not in the winter when children spend more time indoors.
If improperly carried out, the removal of lead-based paint from older houses can significantly increase the risk that children living in such houses will ingest lead dust
情景:孩子们的血液中的铅含量很高,他们的健康情况堪忧。但是我们发现,这帮孩子并不是住在有油漆中含铅的房子里,而更多的人是住在交通比较拥挤的地方,结论是:孩子们的血铅高是由于加在汽油里面的铅导致的。
推理:推理文段的前提中给出了一组统计关联的变量,即,Among those young children with elevated levels of lead in their blood, few live in houses containing lead-based paint, but many live in areas where vehicular traffic is heavy. 结论中两者是因果关系。其属于相关因果推理的典型特点,因此,本题是相关因果推理。 推理结构为:
前提:“汽油含有的铅”和“孩子们的血铅含量”之间存在正相关关系
结论:孩子们的血铅高是由于加在汽油里面的铅导致的。
选题方式:相关因果推理有四个评估方向,简而言之,即,答案选项要么同时提及“汽油含有的铅”和“孩子们的血铅含量”,要么给“孩子们的血铅含量”另外一个原因。
选项分析:
A选项:含有“铅”的颜料在1977年就不让售卖了。本选项没有提及“汽油含有的铅”和“孩子们的血铅含量”,可以排除。
B选项:现在Arumville的居住区的车辆通行率比二十年前要大。因为现在的油都是无铅的了,所以无论汽车数量多少,都不会影响人类血液中是否含有铅,所以本选项可以排除。
C选项:有一些土壤中含有的铅是来自于房屋外部掉下来的颜料。这个选项可以在一定程度上给出孩子们血铅高的原因,也就是人体中铅含量高并不一定是汽油导致的,可以削弱推理文段,但本题问的是加强,所以可以排除。
D选项:Correct. 在Arumville,小孩血液中的含铅量在热天(也就是小孩大部分的时间在外面玩的时候)比冬天(也就是大部分时间在家里的时候)的时候高。小孩子在外面玩的时候要接触土壤,本选项提出了一个“相关性存在”的问题,也就是加强了文中“因”和“果”的相关性,属于CQ1:相关性存在问题。
E选项:如果不恰当的操作,移除老房子的颜料会显著增加住在这种房子里的小孩吞咽含铅的尘土的可能性。前提中已经分开了两部分来讨论,整个相关因果的推理模式是基于住在车流量大的那部分孩子身上的,所以无论住在有铅的房子里的孩子会不会吸食铅,本选项都不能评估整个相关因果推理,可以排除。 |
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