新PREP4

kitebird

A popular beach has long had a dolphin feeding program in which fish are given to dolphins several times a day; many dolphins get as much as half of their food each day there.  Although dolphins that first benefit from the program as adults are healthy and long-lived, their offspring have a lower life expectancy than offspring of dolphins that feed exclusively in the wild.

 

Which of the following, if true, most helps to explain the lower life expectancy of offspring of dolphins feeding at the beach compared to other young dolphins?

 

(A) Sharks that prey on dolphins are less common in the open seas off the beach than in many other areas of the open seas where dolphins congregate.

(B) Many of the adult dolphins that feed at the beach are females that nurse their offspring there.

(C) The fish given to the dolphins at the beach are the same types of fish that dolphins typically catch in the wild

(D) Many dolphins that feed at the beach with their offspring come to the beach only a few times a month.

(E) Adult dolphins that feed at the beach spend much less time teaching their offspring how to catch fish in the wild than do other adult dolphins.

觉得DE都可以。各位是从哪里判断D不对的呢?

sunnyswallow

文中的推理是说offspring自我生存能力下降,导致死亡.而D说他们来海滩的频率,不起作用

smilesansan

但是E选项,较他们捕鱼跟生命的长短有什么必然联系呢?还是不懂啊

matthewfs

dolphins get as much as half of their food each day there 还有食物要自己找，如果小dophlins捕鱼的能力下降，自然影响他们的生存

cookercai

Ｄ是无关项，频率和文中的条件与结果没有任何关系。

Ｅ中的结果是生存能力下降导致原题的结果（活得时间短）

chenae8151

e 在海滩有鱼吃，所以不教后代捕鱼，所以死的多

d说 来海滩少，恰恰证明海滩影响不了海豚的生活方式，就解释不了为什么来海滩的后代死的多了。

peter3008

如果把Ａ选项改为(A) Sharks that prey on dolphins are less common in the open seas off the beach than in beach where dolphins congregate.
这也是一个答案,我一开始就把Ａ看成是这样的了,杯具了

xiaoqiaoli

我觉得这题的关键是要看到“many dolphins get as much as half of their food each day there”，说明人们只喂了dolphins一天所需食物的一半，还有一半需要自己去找。

因此，E选项中海豚妈妈忽视教给小海豚捕食的技巧就会使得小海豚的life expectancy下降，从而小于in the wild的小海豚的life expectancy.