OG12-Verbal-25

弗拉多

25.Which of the following most logically completes the reasoning?


Either food scarcity or excessive hunting can threaten a populationofanimals.Ifthe groupfaces food scarcity, individuals inthe group willreach reproductive maturity laterthan otherwise.Ifthe groupfaces 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 arefossilized mastodon remains from both before and after mastodon populations declined, and __.



 

(A)  there are more fossilized mastodon remains fromthe period before  mastodon populations  began to  decline than from after that period

 

(8)    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 tomastodons

正确选项B。看不懂解释，逻辑推导出现问题
Conclusion: Therefore, it should be possible to determine whether prehistoric mastodons became extinct because of food scarcity or human hunting


灭绝的原因可能是1）food scarcity 2) excessive hunting,
这个原因是由the time they reached reproductive maturity决定的, 然后就不知道怎么推导了。
B选项光提供一个平均到达reproductive maturity的age有什么作用啊？一个年龄并不能支撑上面的time的earlier or later，缺乏对比啊？


求NN

sdcar2010

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.

弗拉多

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.

-- by 会员 sdcar2010 (2011/6/19 22:32:11)

额
我问题就在于B选项只提供了average age，并没有提供normal(你提到的will be older(younger) than normal)
即没有对比的选项，我怎么知道这个就support了呢

sdcar2010

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

BerniceC

我试着回答一下
因为“remains from both before and after mastodon populations declined”，所以说是可以得到two average ages的,分别是average age before mastodon population declined(A1)和average age after mastodon population declined(A2)
如果A1>A2,可得当mastodon population decline时，它 reaching rereproductive maturity earlier，进一步推出decline(也就是extinct)的原因是ecessive hunting;
反之亦然……

BerniceC

哈 大牛的回答就是不同 够简洁