GWD-8-Q3:

In the late 1980’s, the population of sea otters in the North Pacific Ocean began to decline. Of the two plausible explanations for the decline—increased predation by killer whales or disease—disease is the more likely. After all, a concurrent sharp decline in the populations of seals and sea lions was almost certainly caused by a pollution-related disease, which could have spread to sea otters, whereas the population of killer whales did not change noticeably.

Which of the following, if true, most seriously weakens the reasoning?

A. 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.

B. There is no indication that substantial numbers of sea otters migrated to other locations from the North Pacific in the 1980’s.

C. Along the Pacific coast of North America in the 1980’s, sea otters were absent from many locations where they had been relatively common in former times.

D. 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.

E. The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of sea otters.[A]

背景-文章是说水赖的DECLINE 可能是2个原因-  吃他的鲸鱼多 或者 DISEASE （就是污染）

结论是- 是污染 ，不是因为鲸鱼！

当时我看到A 就把他排除了 因为是 我觉得他说鲸鱼会去吃其他的东西，OTHER PREY ， 我就是觉得吃OTHER ，也不一定吃水赖啊！！！

之后就看BCD E 其实看都不象 ，但是就选了E ，觉得E 是在否定 POLUTION 因为文章说是海狮海报的 POLLUTION 影响到了海赖 ， E 的意思说他们根本就不能互相影响！（其实我也觉得E不对 但还是转不过来）

我的天啊 ！PALAPALA 的打这么多 我更糊涂了！

我不知道他说的那个pollution related disease ,which could have spread to sea otters 是说！海狮的污染 造成了给海赖的污染。使海赖数量下降吗？

其实如果只是REALTED 的话 如果A 对 那不就成了A 加强了吗！海狮因为污染死了， 鲸鱼没了食物，就去吃海赖 ，SO 海赖数量少了！这就成加强了啊！

LAWYER 如果看到我的贴子 一定不要因为我写的乱七八糟的就掉头溜哦！

你觉得A不对的理由还是犯了MUST BE 的错误。判断是否WEAKEN的标准是问自己：该选项是否迫使作者重新考虑其观点或必须作出反应（见“考试时如何做逻辑题”）。就像该题，如果有人说了A的情况，作者必须出来澄清WALES是不吃SEA OTTERS的，否则他的观点就会受怀疑。E说的是seals and sea lions 分布较广，SEA OTTERS分布较集中。原文看不出它们活在不同水域。故无关，

谢谢LAWYER ！明白自己对WEAKEN 这里理解的误解了 DOWN 了你写的那个贴子 而且很注意的看了你说的WEAKEN 中MUST BE 的错误！看来真的要到实践中检验才能清楚的明白啊！谢谢！

但我还是对这句话不是很明白：

我不知道他说的那个pollution related disease ,which could have spread to sea otters 是说！海狮的污染 造成了给海赖的污染。使海赖数量下降吗？- 说的是因为污染！

其实如果只是REALTED 的话 如果A 对 那不就成了A 加强了吗！海狮因为污染死了， 鲸鱼没了食物，就去吃海赖 ，SO 海赖数量少了！这就成加强了啊！

是我对文字理解的问题现在想明白了 ！

结论是在海狮他们的DISEASE  传染给 水赖 他们才下降的！！ disease, which could have spread to sea otters

我错误的以为结论是 ：海狮下降导致水赖下降 如果是这个样子 A 一定是加强！因为A 说的就是海狮没了 鲸鱼才去吃水赖的

A：迫使作者反省自己的结论

B：貌似家强

C：啥也没说

D：无关

E：谁的地盘大，无关吧

In the late 1980’s, the population of sea otters in the North Pacific Ocean began to decline. Of the two plausible explanations for the decline—increased predation by killer whales or disease—disease is the more likely. After all, a concurrent sharp decline in the populations of seals and sea lions was almost certainly caused by a pollution-related disease, which could have spread to sea otters, whereas the population of killer whales did not change noticeably.

结论到底是什么呢？？？是对提出的两种减少原因的削弱，还是对哪个是主要的进行削弱?