TPO 29
Task1
Reading
Large numbers of dinosaur fossils have been discovered in deposits on Alaska's North Slope, a region that today experiences an extremely cold, arctic climate. One hundred million years ago, when those dinosaurs were alive, the environment of the North Slope was already inhospitable, especially during the winter when it experienced several months of total darkness. How did the dinosaurs survive the wintertime? Paleontologists have proposed that one of the most common North Slope dinosaurs, the elephant-sized edmontosaur (Edmontosaurus), survived the winter by migrating south to more hospitable regions. Several arguments support the migration hypothesis.
First, the edmontosaur's diet supports the migration hypothesis. Edmontosaurs fed exclusively on plants. Since there would have been no plants growing during the cold and dark North Slope winter, it appears that the edmontosaur must have left for at least part of the year and migrated to more temperate zones to find food.
Second, many edmontosaur skeletons have been unearthed from the same site. This suggests that edmontosaurs lived in herd. Many modern-day migratory animals, such as caribou and buffalo, live and migrate in herds as well. Moving in herds helps animals coordinate their migration. The finding that edmonotsaurs lived in herds further supports the migration hypothesis.
Finally, edmonosaurs were physically capable of migrating long distances. To reach more hospitable regions, the edmontosaur had to migrate about 1,600 kilometers southward. To make such a journey, the edmontosaur needed to move at about five kilometers per hour for several weeks, which is certainly could do. These animals could run very fast, reaching speeds up to 45 kilometers per hour. It could have easily used its locomotive power to move to warmer climate during the harsh arctic winters.
Listening
The hypothesis that the edmontosaur migrated every winter is not convincing.
First, the edmontosaur did not have to migrate to find food. One hundred million years ago the summer temperatures in the North Slope area were warmer than they are today. And remember in arctic regions like the North Slope the sun shines 24 hours a day at the peak of the summer, the warm temperatures and the extensive daylight created incredibly good growing conditions for plants, so much vegetation was produced during the summer that when the vegetation died as the winter came, there was a lot of nutritious dead vegetation around in the winter. The edmontosaur could have easily lived on the dead plant matter during in the winter.
Second, just because edmontosaur lived in herds doesn’t mean they migrated. Animals lived in herds for many other reasons. Living in herds, for example, provides animals extra protection from predators. Having extra protection is useful even for the animals that live in the same area the whole year round. A modern example of this
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is the Roosevelt elk, a large plant-eater. Roosevelt elks live in the forests of western United States, they live in herds, but they do not migrate.
Third, although adult edmontosaur were capable of migrating in long distances. What about edmontosaur that were not yet adults, juvenile edmontosaur were not physically capable of travelling in great distances required to reach warmer territories and would have slowed the herds so much that the herd never would have made to its destination. The herd could not have left the juveniles behind because the juveniles would not have survived on their own. So the whole herd had to stay where they were and survive on the cold North Slope.
Task2
Question:
Do you agree or disagree with the following statement?
To improve the quality of education, universities should spend more money on salaries for university professors.
Use specific reasons and examples to support your answer.
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第二篇:TPO27 托福综合写作文本
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TPO27
Task1
Reading
The Little Ice Age was a period of unusually cold temperature in many parts of the world that lasted from about the year 1350 until 1900C.E. There were unusually harsh winters, and glaciers grew larger in many areas. Scientists have long wondered what caused the Little Ice Age. Several possible causes have been proposed.
First, the cooling may have been caused by disrupting of ocean currents. Before the Little Ice Age, there was a period of unusually warm weather during which glaciers melted. These melted glaciers sent a large amount of cold freshwater into the Gulf Stream, a large ocean current that strongly affects Earth's climate. Some scientists believe that this freshwater was enough to temporarily disrupt the Gulf Stream. Such a disruption could have caused the Little Ice Age.
Second, volcanic eruption could have caused the Little Ice Age. When volcanoes erupt, they send dark clouds of dust and sulfur gas into the atmosphere. These clouds, which can spread over great areas, block some sunlight from reaching Earth's surface. This can decrease the global temperatures. Scientists know of several volcanic eruptions that took place during the Little Ice Age.
Third, Substantial decreases in human populations may have contributed indirectly to the cooling of the climate. For a variety of reasons (disease, warfare, social disruption), the human population just before the Little Ice Age and during the early part of it was lower than it had been in a long time. Forest trees started growing on fields that were no longer used for agriculture. Since trees absorb carbon dioxide, a greenhouse gas, they decrease the greenhouse effect that keeps Earth warm. With more forest trees absorbing carbon dioxide, Earth became cooler.
Listening
Unfortunately, the arguments of the reading passage are a little out of date. Scientists now have new information that shows that none of the ideas the reading passage discusses could account for the Little Ice Age.
First, about the Gulf Stream. Scientists now know that disrupting the Gulf Stream would cause cooling only in Europe and North America, but the Little Ice Age also affected the Southern hemisphere in places like New Zealand and Southern Africa for example. Since the disruption of the Gulf Stream cannot explain why these southern areas became cooler it cannot explain the Little Ice Age.
Second, the volcanoes theory. It's true that if volcanoes eruptions put enough dust into the atmosphere, the result can be a cooler climate. But large amounts of volcanic dust in the atmosphere would have also produced striking visual effects that people would have noticed at the time, for example, dramatically colorful sunset, or snow being grey or brown instead of white. But there are almost no reports of anything like that routinely happening during the Little Ice Age. So it seems that the volcanic eruptions during that period were simply not strong enough to release the large amounts of dust needed to lower global temperatures.
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Third, about forests on farmland stopping the warming greenhouse effect by removing carbon dioxide. There just was not enough time for this effect to work. The human population grew back to previous levels fairly quickly, which meant that forests were soon being cut down again to clear fields for the crops needed to feed the growing population. As a result, we know that the forests mentioned in the reading passage were not there long enough to cause the long term global cooling of the climate.
Task 2
Do you agree or disagree with the following statement? If people have the opportunity to get a secure job, they should take it right away rather than wait for a job that would he more satisfying. Use specific reasons and examples to support your answer.
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