标题: GWD-9-Q20 [打印本页] 作者: zy7988 时间: 2010-3-2 20:57 标题: GWD-9-Q20 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作者: fayeluo 时间: 2010-10-10 10:23
同问同问，这道题什么意思啊？如何选出B的呢？哪位好心的NN给各解释 ！作者: hjxsparrow 时间: 2010-10-10 11:14
food scarcity会导致reproductive maturity later excessive hunting会导致reproductive maturity earlier 也就是说reproductive maturity可以判断灭绝原因 而it should be possible 直到灭绝的原因是food scarcity或者excessive hunting，也就是说可以判断出reproductive maturity的早晚，也就是B选项作者: fayeluo 时间: 2010-10-10 11:33
谢谢2楼！想再请问前面那个原因是什么意思，想表达什么呢？（就是紧接着since那个）作者: hjxsparrow 时间: 2010-10-10 11:58
since there are fossilized mastodon remains from both before and after mastodon populations declined 有在m的数量减少时前后时期的化石