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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.
In this argument,the author contends that the cause of decline on Arctic deer is global warming.To bolster his conclusion,he cites several factors:1.such deer live on islands and they will move over ice from island to island during the course of the year for food.2.hunters say that there is a decline on deer.3.meanwhile,these reports coincide with recent global warming which causes the sea ice to melt.However,it seems to bo somewhat convincing at the first glance,after a thorough reflection,we will find it is fraught with logical flaws.To steady his argument,the author has to provide detailed evidence.
In the first place,the author assumes without justification what hunters said was totally true.Commonsense informs us that it is a poor assumption,for the hunters is likely to live on by hunting deer.If it were the case,then what he said will help to improve the price of deer to some extent.Or perhaps by reporting so,hunters from other regions won't come here for deer anymore so that they will get more profit.Therefore,without evidence on the validity of the reports,the author cannot draw this conclusion arbitrarily.
In the second place,even if it is true that the number of deer decreases,the author cannot asserts global warming will responsible for it.It is entirely possible that because of global warming,the plants which deer feed on will increase a lot and in this way it is not necessary for Arctic to move from this island to that, since they have had already food enough.If it is true,then the author has to provide the situation of the plants eaten by deer,to prove the impossibility.
Finally,even if the evidence turns out to support the foregoing assumptions,it would be still fairly rash to say that because of the global warming's influence on ice between islands,the number of deer declines.It is equally possible that one or two other alternatives will explain it.For example,because the increasing temperature,there is a prevailing illness among Arctic deer,which decimated lots of deer.Also,due to the temperature,the enemy of deer increases to load much pressure on the number of deer.Any of scenarios,if true,will cast doubt on the conclusion of author.In this way,a further investigation should be carried on to demonstrate there is no other explanation for this phenomenon.Otherwise,what the author asserts is unpersuasive at all.
In sum,the author's conclusion is of little credibility.To solidify his conclusion,he has to provide extra explicit information,such as the exact relationship between the number of deer and global warming,to explain why none of alternatives is albe to sustain or why none of them is available.
23分钟= =用了 斑竹推荐的那个写作文的软件 觉得感觉要比写字板好吧 难道这就是传说中的心理原因---- |
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发表于 2012-10-17 21:28:48
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