扫描二维码，直接登录
题库 / Prep2007E1-CR-22
In the late 1980s, the population of sea otters in the North Pacific began to decline. There are two plausible explanations for the decline: predation, possibly by killer whales, or disease. Of these two, disease is the more likely, since a concurrent sharp decline in populations of seals and sea lions is believed to have been caused by disease, and diseases that infect these creatures are likely to be able to infect sea otters also.
Which of the following, if true, most seriously weakens the reasoning?
Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey.
There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations.
Along the Pacific coast of North America in the 1980s, sea otters were absent from many locations where they had been relatively common in former times.
Following the decline in the population of the sea otters, there was an increase in the population of sea urchins, which are sea otters' main food source.
The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of sea otters.
两个原因，原文更偏向于生病。找到一个选项是说原因不应该偏向于是生病的
场景：sea otter 的减少有2个可能原因：被吃或患病。因为seals和sea lions被相信因为是患病而数量急剧减少，所以sea otter减少的原因更有可能是sea otter也受到了这些疾病的感染。所以不太可能是被吃掉。
选项A：Killer whales是靠seals 和 sea lions为食的，如果它们数量少了，Killer whales就会找其他猎物，这样sea otter更可能是被吃掉而不是患病的
场景：sea otter 的减少有2个可能原因：被吃或患病。因为seals和sea lions被相信因为是患病而数量急剧减少，所以sea otter减少的原因更有可能是sea otter也受到了这些疾病的感染。所以不太可能是被吃掉。
选项A：Killer whales是靠seals 和 sea lions为食的，如果它们数量少了，Killer whales就会找其他猎物，这样sea otter更可能是被吃掉而不是患病的。 ---by Sping
提到两个原因：疾病和捕食
结论中给出更有可能是疾病
削弱条件就是［另一个原因］捕食：a
场景：sea otter 的减少有2个可能原因：被吃或患病。因为seals和sea lions被相信因为是患病而数量急剧减少，所以sea otter减少的原因更有可能是sea otter也受到了这些疾病的感染。所以不太可能是被吃掉。
选项A：Killer whales是靠seals 和 sea lions为食的，如果它们数量少了，Killer whales就会找其他猎物，这样sea otter更可能是被吃掉而不是患病的。
otters数量减少有2个可能的原因：1）被whale吃了；2）疾病
P:因为sea lions就因为疾病导致数量急剧减少-> C:otter数量被减少很大可能也是疾病造成的
choice a, 当作为whale主要食物的seals，lions减少以后，whales就开始找其他食物了。correct
“ since a concurrent sharp decline in populations of seals and sea lions is believed to have been caused by disease”，这句的concurrent是关键，海豹和海狮的下降和otter的下降是同时发生的，所以给A选项创造了可能。
做模考的时候半天半天不知道怎么选
再看得时候发现自己把A选项看错了...
Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey.
明明写的是prey on seals and sea lions...不知道为啥脑子里想的是otter...蠢死了
虽然知道A对，但是为啥不能是类比选E呢？？？为什么这样的题型判断有误
虽然知道A对，但是为啥不能是类比选E呢？？？
P otter数量下降了
C 是疾病的原因
E中的海狮海豹居住范围比otter大，不代表otter居住范围小一定没有污染。
A考了100分，B考了60分。A比B高，不能说明人高就一定考高分吧。。。。
登录 或 注册 后可以参加讨论
为什么不可以是类比推理啊。。。
果因推理。前提：水濑更有可能是疾病致死的 结论：因为海狮和海豹是受疾病影响的，所以这种疾病也可能影响水濑
A 给出的是他因。
场景：sea otter 的减少有2个可能原因：被吃或患病。因为seals和sea lions被相信因为是患病而数量急剧减少，所以sea otter减少的原因更有可能是sea otter也受到了这些疾病的感染。所以不太可能是被吃掉。
选项A：Killer whales是靠seals 和 sea lions为食的，如果它们数量少了，Killer whales就会找其他猎物，这样sea otter更可能是被吃掉而不是患病的。