[求助]问OG11上面的sample题目

荷叶田田

3.“Life expectancy" is the average age at death of the entire live-born population.In the middle of the nineteenth century,life expectancy in North America was 40 years,whereas now it is nearly 80 years.Thus,in those days,people must have been considered old at an age that we now consider the prime of life.

Which of the following,if true,undermines the argument above?

B.Most of the gains in life ecpectancy in the last 150 years have come from reductions in the number of infants whodie in their first year of life.

能不能告诉我一下为什么这个选项是对的，我看了半天答案的解释都没弄明白呢~

lukeleng

如果150年前

取样人口10000人,因为医疗卫生等原因,5000名婴儿夭折,其余活到80,average age 就是四十.

那么,就不可能in those days,people must have been considered old at an age that we now consider the prime of life.

荷叶田田

但是为什么说most of gains come from。。。。呢？我还是没明白

lukeleng

在过去的１５０年中，预期寿命增加的大部分归因于婴儿出生当年死亡率的降低．

[此贴子已经被作者于2007-9-21 22:51:35编辑过]

songqi

原题由life expectancy（the average age） in North America was 40 years,whereas now it is nearly 80 years推出结论in those days,people must have been considered old at an age that we now consider the prime of life（现代人的寿命要远远高于古人的寿命）。

这个推理的漏洞是：如果古人平均年龄的降低是被婴儿死亡率过高而拖累的，结论就不成立了，因为古人完全可以和现代人一样长寿。古人平均年龄低，不是因为没有老人。D选项就是这个意思。

[此贴子已经被作者于2007-9-22 23:19:24编辑过]

荷叶田田

啊这样就明白了，谢谢~