PREP中的一道!谢谢!

SuJie0481010

The prairie vole, a small North American grassland rodent, breeds year-round, and a group of voles living together consists primarily of an extended family, often including two or more litters.  Voles commonly live in large groups from late autumn through winter; from spring through early autumn, however, most voles live in far smaller groups.  The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles.

 

Which of the following, if true, provides the strongest support for the explanation offered?

 

(A) It is in the spring and early summer that prairie vole communities generally contain the highest proportion of young voles.

(B) Prairie vole populations vary dramatically in size from year to year.

(C) The prairie vole subsists primarily on broad-leaved plants that are abundant only in spring.

(D) Winters in the prairie voles' habitat are often harsh, with temperatures that drop well below freezing.

(E) Snakes, a major predator of young prairie voles, are active only from spring through early autumn.

为什么不选D,冬天气温低的话,呆在一块不是可以降低死亡率吗?

E选项,如果要解释的话,是因为蛇比较会攻击群体吗?那也可以说成是蛇比较攻击SMALL GROUPS 啊?

谢谢解答!

mhlfly

我觉得题目强调的是yong voles ,如果是D的话，它就不是特指了

wslinfeng

Winters in the prairie voles' habitat are often harsh,从这句话你如果推出因为冬天条件恶劣就需要群居的话，从而加强的话：第一，犯了gmat常见的读者自己推论的逻辑，冬天就一定需要群居吗？这个推论不是gmat要求掌握的尝试，犯了多推一步的毛病；第二，作者问：explained by a seasonal variation in mortality ，注意必须是能联系到mortality,显然冬天的死亡率会更高，显然这是个削弱Voles commonly live in large groups from late autumn through winter，而不是加强

yedeanboy

Winters in the prairie voles' habitat
are often
harsh,从这句话你如果推出因为冬天条件恶劣就需要群居的话，从而加强的话：第一，犯了gmat常见的读者自己推论的逻辑，冬天就一定需要群居吗？这
个推论不是gmat要求掌握的尝试，犯了多推一步的毛病；第二，作者问：explained by a seasonal variation in mortality ，注意必须是能联系到mortality,显然冬天的死亡率会更高，显然这是个削弱Voles commonly live in large groups from late autumn through winter，而不是加强
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wslinfeng,这个解释还是不太理解阿。就拿prep的答案来说，E说捕杀yooung voles的蛇在春秋活跃，那也没说为啥分开住了就可以减少蛇的捕杀了？从原文完全无法推出群居和散居对于蛇捕杀young voles有任何的关系啊？难道分散居住蛇就找不到了？prep的这个题目实在有些莫名其妙阿？
而D中至少说到了冬天气温太低。有些常识的人都知道动物会聚在一起取暖，而严冬对于幼仔特别难熬，所以可以部分解释为啥冬天群居而夏天散居的道理啊

wslinfeng

看来楼主还是思考的挺深入的，但是我们再仔细读这段文章，Voles
commonly live in large groups from late autumn through winter; from
spring through early autumn, however, most voles live in far smaller
groups.  The seasonal variation in group size can probably be explained by a seasonal variation in mortality among young voles他的意思是：Voles在晚秋到冬天这段时间经常是生活在一个很大的群体里面，而在春天和早秋则生活在一个小的群体里面。这种群体数量的季节性变化可以用“因为季节导致的死亡率的变化”来解释。这个问题问加强，显然我们只需要找到群体数量变化和死亡率的关系，这就是“架桥”，必须要把原因和结果链接起来。如果d所说，Winters in the prairie voles' habitat are often harsh, with temperatures that drop well below freezing.冬天天气恶劣对于voles的habitat非常难，这个选线架起了桥梁吗？能把死亡率和群体数量变化链接起来吗？恐怕是不能的，最多只能如你所进一步想的，因为天气恶劣，所以要群居，倒是能解释群体数量变化的原因，注意这是文章的前提，而不是结论，结论是可以用死亡率来解释，要加强的是结论。e选项就能做到这一点，好好体会，可以再交流。提醒一点，加强一定加强的结论，而不是前提。