2. 外语
  3. This section measures your ability to write in English to communicate in an academic environment. There are two writing question

This section measures your ability to write in English to communicate in an academic environment. There are two writing question

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问题 This section measures your ability to write in English to communicate in an academic environment.
There are two writing questions in this section.
For question 1, you will read a passage and listen to a lecture about the same topic. You may take notes while you read and listen. Then you will write a response to a question based on what you have read and heard. You may look back at the passage when answering the question. You may use your notes to help you answer the question. You have 20 minutes to plan and write your response.
For question 2, you will write an essay based on your own knowledge and experience. You have 30 minutes to plan and complete your essay.
Directions: Give yourself 3 minutes to read the passage.
    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 modern 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.
Listen to Track 20.

Directions: You have 20 minutes to plan and write your response. Your response will be judged on the basis of the quality of your writing and on how well your response presents the points in the lecture and their relationship to the reading passage. Typically, an effective response will be 150 to 225 words.
Summarize the points made in the lecture, being sure to explain how they challenge the specific points made in the reading passage.
Narrator
Now listen to part of a lecture on the topic you just read about.
Professor
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 had their legs placed under their bodies, not out to the side, like a crocodile’s? That doesn’t necessarily mean dinosaurs were high-energy endotherms built for running. There’s another explanation for having legs under the body: this body structure supports more weight. So with the legs under their bodies, dinosaurs could 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, but dinosaur bones also have growth rings. Growth rings are a 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—ya 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.
选项
答案What is important to understand from the lecture is that the professor disagrees with the arguments presented in the reading to support the idea that dinosaurs were endotherms, namely that dinosaurs inhabited polar regions; that their legs were positioned underneath their bodies; and that their bones included structures called Haversian canals. In your response, you should convey the reasons presented by the professor for why the information presented in the reading does not prove that dinosaurs were endotherms. A high-scoring response will include the following points made by the professor that cast doubt on the points made in the reading: [*]
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