求教OG verbal 2nd CR-Q25

zdytiffany

25.    Which of the following most logically completes the reasoning?
Either food scarcity or excessive hunting can threaten a population of animals. If the group faces food scarcity, individuals in the group will reach reproductive maturity later than otherwise. If the group faces excessive hunting, individuals that reach reproductive maturity earlier will come to predominate. Therefore, it should be possible to determine whether prehistoric mastodons became extinct because of food scarcity or human hunting, since there are fossilized mastodon remains from both before and after mastodon populations declined, and        .
(A)    there are more fossilized mastodon remains from the period before mastodon populations began to decline than from after that period
(B)    the average age at which mastodons from a given period reached reproductive maturity can be established from their fossilized remains
(C)    it can be accurately estimated from fossilized remains when mastodons became extinct
(D)    it is not known when humans first began hunting mastodons
(E)    climate changes may have gradually reduced the food available to mastodons

是一道填空题啊~正确答案选B。总觉得and让正确选项和前面的一大串decline应该有什么关系，但是又找不出~求教啊！
谢谢！

zdytiffany

对呀，一开始看的真是头昏脑胀的！觉得填空题这类题型有时候会把weaken、support、assumption哪一题揉在一起，只不过换成了填空题的形式来出而已！刚开始读了好多遍都不清楚这道题的空白处究竟是跟前面的是什么样的关系，纠结死~

不过其实这样把题目的意思搞清，还有填空和前面的逻辑关系弄清，再看选型会发现其实选项不迷惑人……

saintaa

在看这一题的时候我也没办法在短时间内看懂，我用的是有没有提到 "age" 相关的选项
C）D）E）选项都可以很快排出，A）B）选项再看一下可排除A选项

Either food scarcity or excessive hunting can threaten a population of animals. （食物稀缺与捕杀过多都会威胁动物族群）
If the group faces food scarcity, individuals in the group will reach reproductive maturity later than otherwise.（食物稀缺时，生殖年龄会后延）
If the group faces excessive hunting, individuals that reach reproductive maturity earlier will come to predominate. （捕杀过多时，生殖年龄会提前）
Therefore, it should be possible to determine whether prehistoric mastodons became extinct because of food scarcity or human hunting, since there are fossilized mastodon remains from both before and after mastodon populations declined, and （因此，要判断史前某种动物灭绝的原因是可能的，因为有物种减少前后的化石而且...）.
(A) there are more fossilized mastodon remains from the period before mastodon populations began to decline than from after that period（物种减少前的化石比减少后的化石多）
(B) the average age at which mastodons from a given period reached reproductive maturity can be established from their fossilized remains（可从化石判定生殖期在何时）
(C) it can be accurately estimated from fossilized remains when mastodons became extinct（可从化石估计灭绝的时间）
(D) it is not known when humans first began hunting mastodons（人类开始狩猎这种动物的时间并不可考）
(E) climate changes may have gradually reduced the food available to mastodons（气候变更使食物变得稀缺）

fantasy1989

Read this sentence: since there are fossilized mastodon remains from both before and after mastodon populations declined,

So you have two populations: before and after the decline. From the population before the decline, you can obtain the NORMAL age to reach reproductive maturity. Then you can obtain the average age to reach reproductive maturity AFTER the decline. Compare these two number. If the former is bigger than the latter, excessive hunting is the cause. If the former is smaller than the latter, food scarcity is the cause.

zdytiffany

还是不懂为什么成熟期在灭绝之前就是正常的呀？真的好笨~

B选项好像有些理解了，and后面的那部分应该是跟since后面部分的作用一样，为therefore后面结果作论据是吧？然后在population下降的前后都有留下fossil，所以可以估计average age来寻找原因~是不是这样子的？

fantasy1989

What the argument says is that:
food scarcity --> reaching rereproductive maturity later than normal, therefore the average age to reach reproductive maturity will be older than normal.
excessive hunting --> reachineg reproductive maturity earlier than normal, therefore the average age to reach reproductive maturity will be younger than normal.

Apparently, the average age to reach reproductive maturity BEFORE the extinction was the NORMAL average.