GWD-8-Q3:

chaos1026

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. 请问A选项是削弱原文中“disease is the more likely”的么？

xuyuanwai

恩，削弱的是disease is the more likely。
作者支持是disease给的理由有两个：
1. seals and sea lions数量少了，很可能是同一种病导致的。
2.killer whales数量没变。（潜台词：如果原因是killer whale，那么KW数量应该变多了，才会吃多了，才会导致see otters减少）

A巧妙地把两个理由都转化为支持killer whale是原因：因为seals and sea lions没了，killer whale才吃sea otters，才导致sea otters少了

chaos1026

嗯，多谢LS啊~

anilolive

C为什么不对？
sea otters都游走了 说明不是the disease的问题 weaken了啊
题目只是说削弱the disease这个原因，没说就非得加强killer whales的啊

hstogether

为什么E不对呢？
E. The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of sea otters.

(我个人的理解是E说明disease是非常有可能spread给sea otters.

waytouing

我也对C很疑惑

sisleycheerup

短文说有两种解释，一个是kw一个是d，作者觉得是d可能性比较大，那么weaken的话，就应该是kw造成了otters的下降。
答案应该围绕着kw捕食o展开的。
A kw没了seals和sea lion，就会捕食其他的（没有特指otter）先保留
E seals 和sea lions分布广吗，比otter数量多。文中说，o下降了，有两个原因，与此同时s和sl也下降了，你觉得E选项有关么？


所以是A

sisleycheerup

C. Along the Pacific coast of North America in the 1980’s, sea otterswere absent from many locations where they had been relatively common in formertimes.
otter消失了，短文的内容是研究消失的原因，weaken的应该短文的观点，那么要削弱，就要提出新观点，或者举例说明旧观点的错误。
C只是在陈述一个事实，所以是错的