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阅读虽然好像都看到过。。然而那篇carbon dioxide真的好难好难。。。我感觉题目都非常细节,大家一定要把第二段好好看一看!不然真的来不及!
One school of thought focuses on the changing positions of the earth’s continents and oceans. The Atlantic Ocean has expanded at the expense of the Pacific Ocean, whereas an ancient equatorial sea that extended across much of Eurasia (called the Tethys Sea) has shrunk to become the modern, much smaller Mediterranean Sea. In addition, the fraction of continents flooded by shallow inland seas has slowly decreased, exposing large amounts of land and creating climates less moderated by the temperature-stabilizing effects of oceans. Computer model simulations show that changes in the arrangement of the continents and the size of inland seas can have important effects on global climate over very long intervals of geologic time. But they are significantly less convincing as sole explanations for the dramatic changes of the past 40 million years.
Another possibility is a long-term decline in the concentration of carbon dioxide in the atmosphere, which would lessen the amount of heat trapped by the atmosphere and lead to “greenhouse cooling.” The amount of carbon dioxide in the earth’s atmosphere over million-year timescales is controlled by two major processes. Chemical weathering of continental rocks removes carbon dioxide from the atmosphere and carries it in dissolved chemical from to the ocean, where it is taken in by marine biota and deposited in sediments on the seafloor. Tectonic activity eventually frees this trapped carbon dioxide, in the earth’s lithospheric plates transports the seafloor to ocean trenches, where subduction carries old crust and sediments down toward the earth’s hot interior. At great depths, the sediments melt, releasing carbon dioxide, which emerges from the volcanic islands that overlie the buried curst and rejoins the atmosphere, completing the cycle.
If the pace of seafloor spreading (and hence of subduction) slowed significantly, less carbon dioxide would be vented to the atmosphere, the atmosphere would become relatively depleted of carbon dioxide and temperatures would fall. In fact, globally averaged seafloor spreading rates slow little or no net change in the past 40 million years. Subduction and volcanism eventually return the carbon dioxide to the atmosphere, but this process requires a long time (tens to hundreds of millions of years) to complete.
1.一个题目在第一段,问现在环境跟原来环境有什么区别,选择较 Warm, Wet(此题也许 是取非题,问现在的环境怎么样,那以前的来取非)
2.R 科学家提出,有逻辑题,以下哪项 weaken 了 R 的观点,定位于二段后半部分. 注意 R 的观点有两个部分 a.weathering 的过程 (即对第一段的解释起到支持作用); b.岩石陆 地的上升 strengthen 了 weathering 的过程.这题要削弱的应该是第二个观点
3.第二段全划线,机理题
还有几篇就比较简单啦:
p.s. 女权好像出现频率真的很高,建议小伙伴把jj里涉及到女权的都认真看!!
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