新托福独立写作解析：面临灭绝的欧亚河狸

　　阅读主要观点提取：

　　总论点：欧亚河狸(Eurasian beaver)由于过度捕杀几近灭绝。人们尝试将它们重新引入之前的栖息地，以便增加它们的数量。然而，这种做法遭到了强烈的反对，理由如下。

　　理由一：河狸会在河流湖泊中修筑水坝，这会阻挡水的流通。水坝会阻挡鱼的迁徙，使它们无法到达交配地点进行繁殖，从而减少鱼的数量。

　　理由二：河狸在河堤挖洞会危害农业。河狸在泥里面挖洞，会导致土壤表层松动，导致水土流失。久而久之，便会缩减河流旁可用作农耕的土地面积。并且，由于肥沃的表层土壤流失，土壤质量变差，减少农民的收成。

　　理由三：河狸会破坏树的生长，影响生态环境。河狸的牙齿锋利，会嚼树干，导致树木死亡。然而，树对英国的生态系统十分重要，它们为动物提供了栖息地、食物等。树减少了，也会导致野生动物减少。

　　听力主要观点提取：

　　总论点：阅读中的观点是有问题的(problematic)。将欧亚河狸重新引入它们的栖息地有很多好处(benefits)。

　　理由一：修筑的水坝不会减少鱼的数量。河狸并不是在所有的河流湖泊中修建水坝，所以鱼还是可以到达繁殖地繁衍后代。另外，河狸修筑的水坝不但可以为小鱼提供充足的食物，还是躲避捕杀者。所以，水坝的存在，可以让一些鱼的数量增加。

　　理由二：总的来说，河狸在地底下挖洞会减少水土流失(erosion)。因为，水土流失取决于河流湖泊的水流速度是否较快。河狸沿着河流挖洞，会降低该区域的水流速度，所以会减少水土流失，可用作农耕的土地也不会减少。

　　理由三：河狸确实会伤害一些树木，但是这反而会增加生态的多样性(diverse ecosystem)。当河狸损毁一部分树的时候，会使一部分地区得到足够的光照。这就给那些需要充足光照才能生长的植物提供了机会，如低矮灌木(low shrubs)。这些植物会吸引一些新的物种，所以增加了该区域生物的多样性。

　　新托福综合写作范文:

　　The idea that reintroducing Eurasian beavers to their former habitats is opposed by the writer with three reasons. Whereas the lecturer demonstrates that the reintroducing has some benefits.

　　First, according to the passage, the dams that the beavers build would block the flow of water, and therefore prevent the migration and reproduction of some fishes. The lecture, however, announces that the beavers build their dams merely in some rivers, and fishes can still swim to their breeding grounds. What’ more, the ponds created by dams will supply habitats for young fish to find food and hide for predators.

　　Second, the passage puts forward that the beavers’ digging behavior would harm the farmland. On contrary, the professor illustrates that digging holes would decrease the overall erosion. Erosion happens when the rivers and streams move fast. While the holes the beavers created would slow down the flow of river which means less erosion of riverbanks. As a result, the farmers will loss less farmland.

　　Finally, the passage claims that beavers chew through wood will kill the trees and harm the ecosystem. In contrast, the professor points out the beavers do harm some trees but not enough to damage the whole ecosystem. Chopping down some trees creates small space exposed to sunlight, and the small space could grow some new types of vegetation which could attract new species of insects, and new species of birds would come to feed on the insects. As a result, the ecosystem would become more diversity.

　　(备注：标红部分是听力关键得分点。)