Direction：

Arctic deer live on islands in Canada's arctic regions. They search for food by moving over ice from island to island during the course of the year. Their habitat is limited to areas warm enough to sustain the plants on which they feed and cold enough, at least some of the year, for the ice to cover the sea separating the islands, allowing the deer to travel over it. Unfortunately, according to reports from local hunters, the deer populations are declining. Since these reports coincide with recent global warming trends that have caused the sea ice to melt, we can conclude that the purported decline in deer populations is the result of the deer's being unable to follow their age-old migration patterns across the frozen sea.

Write a response in which you discuss what specific evidence is needed to evaluate the argument and explain how the evidence would weaken or strengthen the argument.

题目讲解：

Arctic deer live on islands in Canada's arctic regions. They search for food by moving over ice from island to island during the course of the year. Their habitat is limited to areas warm enough to sustain the plants on which they feed and cold enough, at least some of the year, for the ice to cover the sea separating the islands, allowing the deer to travel over it. Unfortunately, according to reports from local hunters, the deer populations are declining. Since these reports coincide with recent global warming trends that have caused the sea ice to melt, we can conclude that the purported decline in deer populations is the result of the deer's being unable to follow their age-old migration patterns across the frozen sea.

Write a response in which you discuss what specific evidence is needed to evaluate the argument and explain how the evidence would weaken or strengthen the argument.

题目讲解

【翻译】

北极鹿生活在加拿大极地区域的岛屿上。它们全年都通过冰块在岛屿间移动来寻找食物。它们的栖居地局限在那些温暖得足以维持它们所需的植物生长，并且在一年的至少某些时候冷到足以让岛屿间的海面结冰以使它们能够在岛屿间旅行的地方。然而，根据当地猎人的报告，鹿的数量正在下降。由于这一报告正好与最近导致海洋冰面融化的全球变暖趋势同时发生，我们可以得出结论：北极鹿数量的下降是它们无法按它们原有的迁移习惯穿越结冰海面的结果。

【分析】

1.没有证据表明warming trend已经导致北极鹿无法像祖先一样在冰块上迁徙

2.也没有证据显示驯鹿的数量减少和全球气候变暖有关

3.其他因素：本地猎人的报告是否准确;没有说明，如果北极鹿不能够迁徙就会死亡或者减少

【提纲】

1report。

2同时发生不说明有因果关系(concurrence)。全球趋势不说明地方。

3即使鹿的数量下降了，也有可能其他因素：基因因素、环境污染、温度下降食物减少。