2015年11月8日
托福阅读词汇题：
Prerequisite=requirement
Considerably=significant
Derive=obtain
Integral=essential
Proper=appropriate
Mean=average Account
for=explain
Discrepancy=inconsistence
Striking=noteworthy
11月8日托福阅读第一篇
题材划分： 天文类
主要内容：太阳光以前没有现在这么亮，后来逐年变亮的。有人认为这和地球上的生物是有关系的，它们为了生存，会自己形成一个系统自动的调节气候。光合作用的greenhouse effect会阻止地面反弹的辐射重新回到太空，这种机制叫做GIGA，GIGA原意是希腊中的神，类似于万物之母的意思。但是科学家对于这种mechanism可以影响地球的程度表示怀疑，认为这个效应并不是万能的。结尾认为这个理论还是比较合理的。
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相关背景知识：
Early in Earth's history, the Sun's output would have been only 70 percent as intense as it is during the modern epoch. In the then current environmental conditions, this solar output would have been insufficient to maintain a liquid ocean. Astronomers Carl Sagan and George Mullen pointed out in 1972 that this is contrary to the geological and paleontological evidence.
According to the Standard Solar Model, stars similar to the Sun should gradually brighten over their main sequence lifetime.However, with the predicted solar luminosity 4 billion (4 × 109) years ago and with greenhouse gas concentrations the same as are current for the modern Earth, any liquid water exposed to the surface would freeze. However, the geological record shows a continually relatively warm surface in the full early temperature record of Earth, with the exception of a cold phase, the Huronian glaciation, about 2.4 to 2.1 billion years ago. Water-related sediments have been found that date to as early as 3.8 billion years ago. Hints of early life forms have been dated from as early as 3.5 billion years, and the basic carbon isotopy is very much in line with what is found today. A regular alternation between ice ages and warm periods is only found occurring in the period since one billion years ago.
When it first formed, Earth's atmosphere may have contained more greenhouse gases. Carbon dioxide concentrations may have been higher, with estimated partial pressure as large as 1,000 kPa (10 bar), because there was no bacterial photosynthesis to reduce the gas to carbon and oxygen. Methane, a very active greenhouse gas that reacts with oxygen to produce carbon dioxide and water vapor, may have been more prevalent as well, with a mixing ratio of 104 (100 parts per million by volume). Based on a study of geological sulfur isotopes, in 2009 a group of scientists including Yuichiro Ueno from the University of Tokyo proposed that carbonyl sulfide (OCS) was present in the Archean atmosphere. Carbonyl sulfide is an efficient greenhouse gas and the scientists estimate that the additional greenhouse effect would have been sufficient to prevent Earth from freezing over.
Based on an "analysis of nitrogen and argon isotopes in fluid inclusions trapped in 3.0- to 3.5-billion-year-old hydrothermal quartz" a 2013 paper concludes that "dinitrogen did not play a significant role in the thermal budget of the ancient Earth and that the Archean partial pressure of CO2 was probably lower than 0.7 bar". Burgess, one of the authors states "The amount of nitrogen in the atmosphere was too low to enhance the greenhouse effect of carbon dioxide sufficiently to warm the planet. However, our results did give a higher than expected pressure reading for carbon dioxide – at odds with the estimates based on fossil soils – which could be high enough to counteract the effects of the faint young Sun and will require further investigation."
Following the initial accretion of the continents after about 1 billion years, geo-botanist Heinrich Walter and others contend that a non-biological version of the carbon cycle provided a negative temperature feedback. The carbon dioxide in the atmosphere dissolved in liquid water and combined with metal ions derived from silicate weathering to produce carbonates. During ice age periods, this part of the cycle would shut down. Volcanic carbon emissions would then restart a warming cycle due to the greenhouse effect.
第二篇
题材划分： 科学类
主要内容： 文章首先定义有机物和无机物的概念，一开始这两者之间是不分的，直到1810年科学家才开始进行分类，以前是按照动物，植物来划分。虽然科学家很想研究有机物，但是他们在研究无机物的时候获得的成就更多一些，这是因为自然界存在很多纯净的无机物，比如说硫。接下来文章讲述了一个实验，科学家烧了无机物得到各种气体固体还有液体之类的，然后通过实验研究气体的质量和数量来了解它的构成。
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第三篇
题材划分：经济贸易类
主要内容：讲述了14世纪欧洲经济的衰退。首先因为气温变低，虽然只是低了几度，但是稍微一点温度的变化都会对农业产生很大的影响，由于气温低了影响了农业，农作物产量就会下降，农民的生活就会变得很惨，于是就拿不出钱，农业不好，资本又少了。然后因为东亚一个帝国的崛起，该帝国中式信仰轻视商业，因此欧洲向亚洲的贸易之路就逐渐衰退了，他们开始向大西洋和欧洲发展。
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