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1、Toefl iBT Practice Test TPO 4 WritingNo. of Questions: 2 Time: approx. 60 minutesBegin TestNow put on your headsetClick on CONTINUE to go onCONTINUEYou have 3 minutes to read the passage.Click to begin reading now .Begin readingEndotherms are animals such as modern birds and mammals that keep their

2、body temperatures constant. For instance, humans are endotherms and maintain an internal temperature of 37C, 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, di

3、nosaurs differ in many ways from modem reptiles, and there is now considerable evidence that dinosaurs were, in fact, endotherms.Polar dinosaursOne reason for believing that dinosaurs were endotherms is that dinosaur fossils have been discovered in polar regions. Only animals that can maintain a tem

4、perature well above that of the surrounding environment could be active in such cold climates.Leg position and movementThere 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

5、efficient only if an animals legs are positioned underneath its body, not at the bodys 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 cana

6、lsThere 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. T

7、he 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.You may have to wait a few seconds for the audio to load and play.Directions: You have 20 minutes to plan and write your response.

8、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.Question: Summarise the points made in the lecture, being

9、 sure to explain how they challenge the specific points made in the reading 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 37C, no matter whether the environment i

10、s 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.换行请按Ctrl+EnterW

11、rite your response here.Polar dinosaursOne 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 positio

12、n and movementThere 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 animals legs are positioned underneath its body, not at the bodys side, as they are

13、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 canalsThere is also a connection between endothermy and bone structure. The bones of endotherms usually inclu

14、de 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 fossil

15、ized bones of dinosaurs are usually dense with Haversian canals.Directions: Read the question below. You have 30 minutes to plan, write, and revise your essay. Typically, an effective response will contain a minimum of 300 words.换行请按Ctrl+EnterWrite your response here.Question:Do you agree or disagree with the following statement?In twenty years, there will b