人类是恒温动物，所谓恒温动物就是指可以保持体温恒定的动物，人类体温一般不随环境变化，维持在37摄氏度。今天给大家分析的是托福TPO4的综合写作真题，关于恒温动物的话题。北京新航道老师将针对这一篇文章从观点提炼，材料分析，笔记等方面展开具体详细的指导，考生对它的驾驭力，让大家争取拿托福写作。让我们开始吧!

　　阅读材料：

　　Endotherms are animals such as modern birds and mammals that keep their body temperatures constant. For instance, humans are endotherms and maintain an internal temperature of 37℃, no matter whether the environment is warm or cold. Because dinosaurs were reptiles, and modern reptiles are not endotherms, it was long assumed that dinosaurs were not endotherms. However, dinosaurs differ in many ways from modern reptiles, and there is now considerable evidence that dinosaurs were, in fact, endotherms.

　　恒温动物是指诸如现代鸟类和哺乳动物这种可以保持体温恒定的动物。比如，人是恒温动物，无论环境温度是怎样，体温都维持在37℃。因为恐龙属于爬行动物，而现代的爬行动物都不属于恒温动物，所以长期以来恐龙都被当做是变温动物。然而，恐龙在地方都同现在的爬行动物不一致。同时，现在有大量的证据表明恐龙其实是恒温动物。

　　Polar dinosaurs

　　One reason for believing that dinosaurs were endotherms is that dinosaur fossils have been discovered in Polar Regions. Only animals that can maintain a temperature well above that of the surrounding environment could be active in such cold climates.

　　极地恐龙

　　主张恐龙属于恒温动物的原因是在极地发现了恐龙。只有能够维持体温的动物才能在如此寒冷的地方生存。

　　Leg position and movement

　　There is a connection between endothermy and the position and movement of the legs. The physiology of endothermy allows sustained physical activity, such as running. But running is efficient only if an animal's legs are positioned underneath its body, not at the body's side, as they are for crocodiles and many lizards. The legs of all modern endotherms are underneath the body, and so were the legs of dinosaurs. This strongly suggests that dinosaurs were endotherms.

　　腿的位置和运动方式

　　恒温动物和腿的位置及运动方式有联系。恒温动物的生理结构允许它们进行持续的物理运动，比如奔跑。但是，只有当腿长在身体的下部而不是两侧的时候才能地奔跑，而像鳄鱼或者蜥蜴的腿，都是长在身体两侧的。所有现代恒温动物的腿都是长在身体下部的，而恐龙的腿也具有同样的特点。这很有力地说明了恐龙是恒温动物。

　　Haversian canals

　　There is also a connection between endothermy and bone structure. The bones of endotherms usually include structures called Haversian canals. These canals house nerves and blood vessels that allow the living animal to grow quickly; and rapid body growth is in fact a characteristic of endothermy. The presence of Haversian canals in bone is a strong indicator that the animal is an endotherm, and fossilized bones of dinosaurs are usually dense with Haversian canals.

　　哈弗森管

　　恒温动物和骨结构之间也有相应的关联。恒温动物都有一种名为哈弗森管的骨结构。这种哈弗森管可以保护神经和血管以动物地生长，而生长恰恰是恒温动物的一个特征。哈弗森管的存在可以有力的说明该动物属于恒温动物，而恐龙的骨骼化石中常常可以观察到哈弗森管。

　　阅读部分需要提取的观点是：

　　- Main point: 恐龙是恒温动物

　　- Sub point 1: 恐龙的化石在极地发现，而极地只有恒温动物生存，所以恐龙是恒温动物。

　　- Sub point 2: 恐龙有跟恒温动物一样的腿结构，所以恐龙是恒温动物。(这个是有逻辑漏洞的，一会在听力部分我再解释)

　　- Sub point 3: 恐龙跟恒温动物一样的哈弗森管，所以恐龙是恒温动物。

　　观点抽出方法：来源：北京新航道托福培训

　　这篇文章的观点抽取上难度不是很大，但是问题的关键是要看到这个论证的逻辑链，而找到的逻辑链有助于我们在听力的时候系统地提取有用信息。

　　分论点一的逻辑是：只有恒温动物能适应极地的寒冷气候，而恐龙能适应，所以恐龙是恒温动物。这个只有让这个逻辑关系合格，所以只能翻过极地的状态和恐龙的状态了，、

　　分论点二的逻辑是：是什么?是“所有现代恒温动物的腿都是长在身体下部的，而恐龙的腿也具有同样的特点”吗?不是的，腿长在身体下部是恒温动物的“必要不充分条件”。段内的逻辑是这样的：腿长在身体下部à可以快跑à可以持续剧烈运动à是恒温动物。然后呢?把恐龙带进去。哪个地方是有可能反驳的呢?听力部分是要打碎这个逻辑链。

　　分论点三的逻辑是：有哈弗森管à可以保护血管和神经à可以生长à恒温动物。而恐龙恰好有恒温动物。反驳的时候也是打碎逻辑链啦。

　　这种科学类的题目，都是建立在推测的基础上的，所以推理论证就是最常用的方式啦。因为，反驳的时候也用打碎逻辑链的方式。

　　听力材料：

　　Many scientists have problems with the arguments you read in the passage. They don't think those arguments prove that dinosaurs were endotherms.

　　科学家对你们刚刚听到的文章持有不同意见。他么认为这些理由不能支持恐龙是恒温动物。

　　Take the polar dinosaur argument. When dinosaurs lived, even the Polar Regions, where dinosaur fossils have been found, were much warmer than today, warm enough during part of the year for animals that were not endotherms to live. And during the months when the Polar Regions were cold, the so-called polar dinosaurs could have migrated to warmer areas or hibernated like many modern reptiles do. So the presence of dinosaur fossils in Polar Regions doesn't prove the dinosaurs were endotherms.

　　先说一下极地恐龙的观点。当恐龙存在的时候，极地，也就是这些发现化石的地方比现在要暖和。而且当极地很冷的几个月里，这些极地恐龙会迁徙到暖和的地方或者像现在爬行动物一样选择冬眠。所以，在极地发现恐龙化石不能证明恐龙是恒温动物。

　　Well, what about the fact those dinosaurs have their legs placed under their bodies, not out to the side like crocodiles. That doesn't necessarily mean dinosaurs were high-energy endotherms built for running. There is another explanation for having legs under the body. This body structure supports more weight, so with the legs under their bodies, dinosaurs can grow to a very large size. Being large had advantages for dinosaurs, so we don't need the idea of endothermy and running to explain why dinosaurs evolved to have their legs under their bodies.

　　那么，恐龙的腿在身体下方而不是两侧是怎么回事呢?这个是不足以证明恐龙是可以进行奔跑类剧烈运动的恒温动物。腿生长在身体下部对于恐龙是别有的意义的。这样的结构可以支撑的重量。所以腿长在身体下部可以让恐龙长到大。对于恐龙来说，巨大的重量是有意义的，所以没有比用要用恒温动物和奔跑来解释为什么恐龙进化出这样的身体结构的。

　　Ok, so how about bone structure? Many dinosaur bones do have Haversian canals, and that is true. The dinosaur bones also have growth rings. Growth rings are thickening of the bone that indicates periods of time when the dinosaurs weren't rapidly growing. These growth rings are evidence that dinosaurs stopped growing or grew more slowly during cooler periods. This pattern of periodic growth, you know, rapid growth followed by no growth or slow growth, and then rapid growth again, is characteristic of animals that are not endotherms. Animals that maintain a constant body temperature year-round as true endotherms do grow rapidly even when the environment becomes cool.

　　恩，那么骨结构呢?恐龙确实有哈弗森管，这是事实不能否认。但是与此同时，恐龙还有生长环。生长环上比较厚的环节说明当时恐龙生长的缓慢。因此，生长环证明了恐龙在冷的时候生长缓慢甚至停止生长。这是一种周期性生长：一段时间不生长或者生长缓慢，然后接着生长。拥有这样生长方式的动物不是恒温动物。真正的恒温动物可以一年四季保持恒定的体温，因此可以在天气很冷的情况下生长。

　　听力笔记内容：

　　Main point：don't

　　Sub point one: warmer, migrated, hibernated

　　Sub point two: doesn't necessarily, for running, more weight, advantages

　　Sub point three: Haversian canals, growth ring, slowly or stop V.S. rapid, periodic

　　上面是一篇关于恒温动物的托福综合写作话题，北京新航都老师给了我们比较详细和深入的讲解。希望大家可以认真看看，多体会总结。自己的综合能力。

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