Original:Why do some animals die out?In the past two hundred years people have caused many kinds of animals to die out-to become extinct. People keep building houses and factories in fields and woods. As they spread over the land, they destroy animals homes. If the animals cant find a place to live, they die out. Sixteen kinds of Hawaiian birds have become extinct for this reason. Other animals, such as the Florida Key deer, may soon die out because they are losing their homes. Hunters have caused some animals to become extinct, too. In the last century, hunters killed all the passenger pigeons in North America and most of the buffalo.Today they are fast killing off hawks and wolves. Pollution is killing many animals today, too. As rivers become polluted, fish are poisoned. Many die. Birds that eat the poisoned fish cant lay strong, healthy eggs. New birds arent born. So far, no animals have become extinct because of pollution. But some, such as the bald eagle and the brown pelican, have become rare and may die out.Scientists think that some animals become extinct because of changes in climate. The places where they live become hotter or cooler, drier or wetter. The food that they eat cannot grow there any more. If the animals cant learn to eat something else, they die. Dinosaurs may have died out for this reason.Summary:Model 1:In this passage/article, the author mainly（主要地） talks about/tells us / This article/ passage mainly tells us why in the past two hundred years, many kinds of animals have died out. Overall（总体上来说）, there are several reasons for it. First, people keep building houses and factories in fields and woods, which destroys animals homes. Second/Secondly, hunters killing has also caused some animals to become extinct. Besides, some animals arent able to bear strong offspring and nor do they have enough food to eat because of pollution and climatic changes. In a word, peoples keeping building houses and factories in fields and woods, hunters killing and pollution and climatic changes are the reasons which caused many kinds of animals to die out-to become extinct.Model 2:This paper deals with (论述)/ This article focuses on the topics of / This paper provides an analysis（分析） of / This paper expresses（表达） views on the reason why in the past two hundred years, many kinds of animals have died out. On the whole(总体上来说), there are several reasons for it. To begin with（首先）, people keep building houses and factories in fields and woods, which destroys animals homes. Furthermore（其次）, it is hunters killing that has also caused some animals to become extinct. In addition（另外）, owing to pollution and climatic changes, neither do some animals can bear strong offspring nor they can have enough food to eat. In summary（总而言之）, peoples keeping building houses and factories in fields and woods, hunters killing and pollution and climatic changes are the reasons which caused many kinds of animals to die out-to become extinct.Model 3:(The writer of this essay) tries to explore（探讨） / (The writer of) this paper discusses（讨论） /analyzes（分析）/elaborates（阐述） why in the past two hundred years, many kinds of animals have died out. There are several reasons for it. Overall, there are several reasons for it. First of all, people keep building houses and factories in fields and woods, which destroys animals homes. Whats more/ moreover, hunters killing has caused some animals to become extinct as well. Last but not least, because of pollution and climatic changes, some animals arent able to bear strong offspring and nor do they have enough food to eat. To conclude, peoples keeping building houses and factories in fields and woods, hunters killing and pollution and climatic changes are the reasons which caused many kinds of animals to die out-to become extinct.注：开头总述可用的模版：u In this passage/article, the author mainly talks about/tells us/ This article/ passage mainly tells us.u This paper deals with / This article focuses on the topics of / This paper provides an analysis of / This paper expresses views on.u (The writer of this essay) tries to explore / (The writer of) this paper discusses /analyzes/elaborates.u Overall/on the whole:总体上来说中间分述可用的模版： 首先：first, to begin with, first of all 其次：second, secondly, furthermore, whats more, moreover 再次，此外：besides, in addition 最后但同样重要的：last but not least 最后总结可用的模版：in a word/ in brief/ in short/in summary/ in conclusion, to sum up/ to conclude：总之,简言之作者最后的结论和建议可用模版： The author suggests（建议）/recommends（建议）/concludes（下结论)that. It is suggested（建议） that. The authors suggestion（建议）/conclusion（结论）is that The author finds it necessary（必要的）/essential(必要的) to .