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题库 / Prep2007E1-CR-4
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?
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.
Many of the adult dolphins that feed at the beach are females that nurse their offspring there.
The fish given to the dolphins at the beach are the same types of fish that dolphins typically catch in the wild.
Many dolphins that feed at the beach with their offspring come to the beach only a few times a month.
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.
类比，被投喂的海豚后代比野生的存活率低
加强，寻找二者不同
A、对比不同海域的shark
B、被投喂的成年海豚为母
C、控制被投喂/野生海豚食物变量，相似点，削弱
D、无对比
E、授人以鱼不如授人以渔，二者不同，加强
A选项 如果是因为鲨鱼 应该是大小海豚都会被吃但原文只说了幼豚lower life E选项因为幼豚没有学会捕食本领 人类给的吃的又不够 迟早要下海捕食 就会饿死
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.
虽然成年后首次受益于该计划的海豚健康长寿，但它们的后代的预期寿命低于只在野外进食的海豚的后代。
KEY WORDS:成年后as adults才首次受益于该计划——幼时已养成野外捕食能力；只在exclusively野外进食的后代——是否也具有该能力？
C：在program喂食的后代比在野外的寿命短
通俗的说：后代之间的差异，由于其爹妈教的不一样。
expectancy ，期待，预料；their offspring have a lower life expectancy ，他们的后代预期寿命更低。
off，介词表离，距离；an island off the coast of Spain 西班牙海岸附近的岛。
A，岸边的鲨鱼更少。CR：鲨鱼更少，幼仔更多，削弱。
choice A：捕食海豚的鲨鱼更经常出现在海滩边，比起那些海豚聚集的地方
A is exactly the opposite of what we want. It would help if there were MORE sharks near the feeding area, not fewer..
A 鲨鱼吃海豚，没提海豚的后代。
B 跟公母没关系，难道当爸爸的不管孩子了吗。
C 有吃的就挺好的了，还管吃的鱼的种类么。
D 来几次和生命健康无关
E 爸妈没教孩子怎么自然捕食，丧失技能，因为人类喂养的食物只够他们一半的量，可能吃不饱。真可怜
A选项最大的问题其实是它一直在强调open seas，然而这个program是beach的program，我开始没注意是beach的program，也在疑惑A选项，回头看了原文后直接排除A了。因为海豚在open seas中多还是少跟这个program是肯定没有关系的。这个program只会引起beach旁边的海豚更加密集。
感觉E选项也有些牵强，A选项相比还好些，鲨鱼靠近海豚聚集的地方，然后吃掉海豚。而野外捕食的海豚，不那么聚集，所以鲨鱼也少，因而寿命长。
文中有一句话说，已成年的海豚受到了喂食的好处从而更健康长寿，A选项没有将已成年海豚与其子孙后代的关系考虑进去，并且与原文阐述信息相左。
如果是A的话，那么成年的海豚计划中的海豚怎么没有因为聚集而被鲨鱼吃掉呢？？所以A显然是不对的，因为这道题是让成年海豚计划里的海豚和幼年的相比，找出其不同点，独立第三方因素即鲨鱼不是这个不同点，如果它说小海豚容易去open sea 玩耍，成年海豚不去，所以鲨鱼吃了小海豚，这样才算不同点，但文中显然没有指出
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A.捕食海豚的鲨鱼主要在哪出没（没有提到项目和海豚宝宝，无关）B 许多受益于项目的海豚是哺育宝宝的海豚妈妈（推不出宝宝为何脆弱，无关）C 投食的鱼和海豚在海里捕食的鱼是一样一样的（证明成年鱼的相似性，与推理无关）D 许多在沙滩吃食的海豚和他们的宝宝们一个月只来几次（推不出宝宝为何脆弱，无关）E 在沙滩吃食的成年海豚比其它成年海豚更少时间教他们的宝宝如何在野外捕鱼（正确，因为项目占用了爸妈的时间，导致海豚宝宝野外捕鱼奇数差，所以很快就饿死了。）
类比推理。 前提：受益于该项目（人工投食）的成年海豚健康长寿。结论：受益于该项目的海豚宝宝也应该比其他野外生养的海豚宝宝健康长寿。 问题：削弱结论，寻找该项目损害海豚宝宝健康的因素。