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TPO4托福综合写作阅读原文文本
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°C, 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 modem reptiles, and there is now considerable evidence that dinosaurs were, in fact, endotherms.
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.
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.
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.
TPO4托福综合写作听力原文文本：
Many scientists have problems with the arguments you read in the passage. They don't think those arguments prove that dinosaurs were endotherms.
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.
Well, what about the fact that 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.
Ok, so how about bone structure? Many dinosaur bones do have Haversian canals, that's 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.
从近年来的
在写一边倒的文章的时候，多数考生喜欢采用经典的五段式写法，即开头段、结尾段、中间三段三个分论点论证。这样的写法当然无可厚非，然而多数学生会碰到两个问题，一是我只能想到两个理由，第三个理由写不出来怎么办?二是我三个理由都写完了，但是字数不够300字怎么办?这样的情况，就需要我们的救命稻草"让步段"出场了。
让步段，顾名思义，就是退了一步的段落。例如，2009年6月27日的题目，For further career success, is relate well to other people more important than studying hard at school? 选择了同意的立场，写完了三个同意的理由之后，可以再写一点让步段论述一下反方的观点，即在学校学习好也很重要。写让步段的好处有很多，一是上文提及的最实际的用途---凑字数，二是从行文逻辑看，写一段让步段也可以展现考生思维的严密性。只要时间允许，此种一举多得的做法为何不尝试呢?
但是，让步段写作也需要遵循一定的原则。考生在写作时，应当按照三部曲进行：1)写出一个反方观点 2)进行一定程度的削弱 3)重申自己的观点。
1) 写出反方观点
这一步大多数同学都做得不错，但是在提出反方观点之前，可再加上一些连接词，例如admittedly, nevertheless等等。还拿之前拿到题目做例子，For further career success, is relate well to other people more important than studying hard at school? 总观点是同意，让步段写学习好也挺重要的。第一步引出反方观点时，应写：Admittedly, acquiring an excellent GPA is one significant proof of your ability, for "study" is one of the major tasks that students are supposed to fulfill in school.
2) 进行一定程度的削弱
这是大多数同学会忽略的一步。很多同学在写让步段的时候，喜欢跳过第二步，直接重申自己的观点，然而这样的写法会显得逻辑上牵强，行文也显得生硬。因此，在提出反方观点时要进行一定的削弱。例如在写完上文那句话之后，应加上：However, the outstanding scores only prove the intelligence of the student, while the EQ, largely reflected by how well you relate with others, plays an utmost significant role in the future career success.
3)重申自己的观点
这一步非常重要，因为让步段的提出仅仅是小插曲，重要的还是自己的观点。切不可写了让步段，就忘了自己的立场，那样就是得不偿失了。因此，在写完上面两句话之后，需要再加上一句，therefore, I still hold the opinion that relate well with others is more important than acquiring high scores in school.
在让步段的写作当中，尤其需要注意两点：1是第二步的削弱过程，这样可使文章看起来不那么唐突，更为流畅。2是另外还需注意字数的控制，让步段切不可写得超过之前的论述段的长度，否则就有观点不明确的嫌疑了。
以上就是小编整理的精彩内容希望可以帮助托福考生，更多精彩内容尽在，预祝托福考生取得理想成绩!