Herbicides allow cereal crops to be grown very efficiently, with virtually no competition from weeds. In Britain, partridge populations have been steadily decreasing since herbicide use became widespread. Some environmentalists claim that these birds, which live in and around cereal crop fields, are being poisoned by the herbicides. However, tests show no more than trace quantities of herbicides in partridges on herbicide-treated land. Therefore, something other than herbicide use must be responsible for the population decrease.
Which of the following, if true about Britain, most seriously weakens the argument?
The elimination of certain weeds from cereal crop fields has reduced the population of the small insects that live on those weeds and that form a major part of partridge chicks' diet.
Since partridges are valued as game birds, records of their population are more carefully kept than those for many other birds.
Some of the weeds that are eliminated from cereal crop fields by herbicides are much smaller than the crop plants themselves and would have no negative effect on crop yield if they were allowed to grow.
Birds other than partridges that live in or around cereal crop fields have also been suffering population declines.
The toxins contained in herbicides typically used on cereal crops can be readily identified in the tissues of animals that have ingested them.
果因推理
果:P鸟的数量下降
因:是除草剂导致的 加强
A 除草剂把杂草灭了导致P鸟没虫吃了。正好加强了因为除草剂导致数量下降
B P鸟很珍贵,无关
C 这是在说除草剂的优势,无关
D 其他的鸟也下降了,无所知是什么引起的
E 这直接反对了前提,错
这解释的太清楚了,谢谢!
CQ2果因间接性问题
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A除草剂多导致 B鸟减少,典型因果间接性问题,正确选项是提供了一个事实C打通了A-C-B的这条路,加强了A-B的逻辑。 而原文结论是A-B逻辑不成立,但题目问的是哪个选项削弱A-B逻辑,固选择加强A-B逻辑的选项。
果因
∴partridge(P)数量减少
∵没有P接触除草剂的证据,所以是其他原因导致P减少
削弱,即说明P减少就是因为除草剂,排除他因or增强链条
A、种子因为杀虫剂减少→P吃的昆虫减少(从直接毒P到间接毒P,还是除草剂的锅,跟其他原因无关),CQ2,CORRECT
B、P很珍贵,记录它数量要比记录别的鸟更仔细;无关,甚至他因增强
C、除草剂不影响谷物产量;无关
D、其他住在附近的鸟也在减少;无关
E、如果动物消化了除草剂中的毒素,毒素是可以被识别的;他因增强
gap: herbicide use 不等于 poisoned by herbicide
看清结论细节!!herbicide use!没说一定是毒死的,只要能反驳不是herbicide的都可以——只要能说明是herbicide的都可以
看清楚这个间接逻辑:农药通过间接使鸟类食物减少的方式导致了鸟数量的decline。选A。
此题A导致B导致C,说明 间接导致也是导致, 那么相关因果中的 CQ因果间接性问题 是否与此有冲突? 这个CQ认为间接推出作为CQ的点
这算间接因素吧,a虽然没有直接导致b,但a导致了c,c导致了b,所以ab还是正相关
看了个if true就答题了,误解提问为if assumption is true,找conclusion……
Argument: 由于在鸟的体内检测不到大量的农药,所以农药中毒不是导致鸟的数量减少的原因。鸟的数量减少是由于农药之外的其他因素。
反驳Argument:即使鸟类不是因为”农药中毒“而导致数量减少,”农药本身“仍然是导致鸟数量减少的因素。换句话说,我们要找的选项是能够证明农药通过其他途径导致鸟的数量减少(不是用鸟类中毒这种方式)。
现在看选项A: 使用农药导致野草数量下降,野草数量下降导致虫子减少,虫子减少导致鸟类食物减少,食物减少导致鸟的数量下降。所以农药通过间接使鸟类食物减少的方式导致了鸟数量的decline。选A。
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trace quantities of 微量
P: no poison found in birds C: must be something else that kills the bird./因果推/weaken:IT IS Still herbicide that kills bird, 只有a说了仍然是h kill bird,只不过间接非直接。
想知道这里需要weaken的argument是指环境学家认为是鸟are being poisoned by the herbicides ;还是指something other than herbicide use must be responsible for the population decrease.?
a选项 证明了herbicide use 对鸟的数量有间接的影响,因为减少了鸟的食物的数量。
E, herbicides已经分解成为毒素 入侵组织器官了,所以herbicide本身只是微量存在,但依然是毒性的源头
选项A不是滑坡理论吗?除草剂→草减少→吃这种草的昆虫减少→吃这个昆虫的鹧鸪减少,不能推出除草剂能导致鹧鸪数量减少啊
还想问一下选项E为什么不对呢?谢谢老师~
E的意思是杀虫挤毒素能够readily(adv.容易地;乐意地;无困难地)被鉴定出来,只要动物吃了差冲剂,言外之意就是p鸟
E的意思是杀虫挤毒素能够readily(adv.容易地;乐意地;无困难地)被鉴定出来,只要动物吃了差冲剂,言外之意就是p鸟
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