【小站原创】官方真题Official39托福综合写作真题文本及答案解析
- 2017年06月14日14:54 来源：小站教育作者：小站托福编辑
- 参与（3） 阅读（29788）
在托福写作备考的过程时候，大家往往会把更多的精力放在托福独立写作的准备中。但是，想要冲刺的托福写作的高分，综合写作也是我们必须要冲过的一个难关。那么，在以下内容中，就为大家带来官方真题Official39托福综合写作题目文本及答案解析，希望能为大家的备考带来帮助。
官方真题Official 39-综合
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.
Question: Summarize the points made in the lecture, being sure to explain how they challenge the specific theories presented in the reading passage.
At the end of the Triassic period 200 million years ago, there was a mass-extinction event that caused the extinction of more than half of all living species. It was this extinction event that allowed dinosaurs to become the dominant species for the next 145 million years. We do not know exactly what happened that eliminated so many species in a relatively short period of time, but there are several possible explanations.
One theory involves the decline of sea levels. Near the end of the Triassic period, sea levels were fluctuating. When sea levels fall, the habitats for ocean populations that live in the shallows and land species that live on the coast are destroyed. The destruction of coastal and shallow-ocean species would have had a profound effect on food chains worldwide, leading to mass extinctions.
Another theory involves massive climate cooling. The end of the Triassic period was marked by widespread volcanic activity. The volcanoes released large amounts of sulfur dioxide (S02). A rise in atmospheric S02 is known to cause a lowering in global temperatures. Such climate change could have devastated many species and led to the extinctions.
The third theory involves an asteroid strike. Asteroids (objects from outer space) occasionally collide with Earth. When an asteroid hits Earth’s surface, it often displaces large amounts of soil and crushed rock, leaving behind a depression, or crater. The displaced debris is thrown up into the atmosphere where it can block out sunlight for many months or even a few years. A sufficiently massive asteroid impact at the end of the Triassic period may have blocked sunlight long enough for most plants to die and many animal species to then starve.
登陆后查看完整解析。
