15. 云和气候变化预测
云对climate的影响。说科学家探究云对二氧化碳和温室效应有没有影响，结论是影响不大。第一云干嘛来着忘了，第二一种云在海上 circulate什么什么。。然后最后一小节说科学家在电 脑上模拟的时候如果算云的话好象是说只能推测几天的天气，如果不算云的话就没这个问题，最后说还不如忽略云的影响。
As of the late 1980’s, neither theorists nor large-scale computer climate models could accurately predict whether cloud systems would help or hurt a warming globe. Some studies suggested that a four percent increase in stratocumulus clouds over the ocean could compensate for a doubling in atmospheric carbon dioxide, preventing a potentially disastrous planetwide temperature increase. On the other hand, an increase in cirrus clouds could increase global warming.
That clouds represented the weakest element in climate models was illustrated by a study of fourteen such models. Comparing climate forecasts for a world with double the current amount of carbon dioxide, researchers found that the models agreed quite well if clouds were not included. But when clouds were incorporated, a wide range of forecasts was produced. With such discrepancies plaguing the models, scientists could not easily predict how quickly the world’s climate would change, nor could they tell which regions would face dustier droughts or deadlier monsoons.
24. The author of the passage is primarily concerned with
(A) confirming a theory
(B) supporting a statement
(C) presenting new information
(D) predicting future discoveries
(E) reconciling discrepant findings
25. It can be inferred that one reason the fourteen models described in the passage failed to agree was that
(A) they failed to incorporate the most up-to-date information about the effect of clouds on climate
(B) they were based on faulty information about factors other than clouds that affect climate
(C) they were based on different assumptions about the overall effects of clouds on climate
(D) their originators disagreed about the kinds of forecasts the models should provide
(E) their originators disagreed about the factors other than clouds that should be included in the models
26. It can be inferred that the primary purpose of the models included in the study discussed in the second paragraph of the passage was to考缺陷，最后一句话改写
(A) predict future changes in the world’s climate
(B) predict the effects of cloud systems on the world’s climate
(C) find a way to prevent a disastrous planetwide temperature increase
(D) assess the percentage of the Earth’s surface covered by cloud systems
(E) estimate by how much the amount of carbon dioxide in the Earth’s atmosphere will increase
27. The information in the passage suggests that scientists would have to answer which of the following questions in order to predict the effect of clouds on the warming of the globe? 原文取非，D不对，光知道这个不行，因为还有别的云
(A) What kinds of cloud systems will form over the Earth?
(B) How can cloud systems be encouraged to form over the ocean?
(C) What are the causes of the projected planetwide temperature increase?
(D) What proportion of cloud systems are currently composed of cirrus of clouds?
(E) What proportion of the clouds in the atmosphere form over land masses?
作为20世纪80年代末，既不是理论家，也不是大规模的计算机气候模型能准确地预测云系是否会帮助或伤害变暖的地球。一些研究表明，增加百分之四以上的海洋层积云可以弥补大气中二氧化碳含量增加一倍，防止潜在的灾难性的planetwide温度升高。另一方面，卷云增加可能会加剧全球变暖。
，云代表由14个这样的模型的研究说明在气候模型中最薄弱的元素。双目前的二氧化碳量为世界气候的预测比较，研究人员发现，该模型很好同意如果不包括云层。但是，当云被纳入生产，广泛的预测。这种差异困扰模型，科学家们不能轻易预测全球气候改变的速度有多快，也无法告诉哪些地区将面临干旱 dustier或致命的季风。
16. supernova (36套)
astronomers observe a supernova that is dimmer than expected because of dust screening，这个应该是36套里有，有点印象
If a supernova (the explosion of a massive star) triggered star formation from dense clouds of gas and dust, and if the most massive star to be formed from the cloud evolved into a supernova and triggered a new round of star formation, and so on, then a chain of star-forming regions would result. If many such chains were created in a differentially rotating galaxy, the distribution of stars would resemble the observed distribute in a spiral galaxy.
This line of reasoning underlies an exciting new theory of spiral-galaxy structure. A computer simulation based on this theory has reproduced the appearance of many spiral galaxies without assuming an underlying density wave, the hallmark of the most widely accepted theory of the large-scale structure of spiral galaxies. That theory maintains that a density wave of spiral form sweeps through the central plane of a galaxy, compressing clouds of gas and dust, which collapse into stars that form a spiral pattern. (160 words)
7. The primary purpose of the passage is to
(A) describe what results when a supernova triggers the creation of chains of star-forming regions
(B) propose a modification in the most widely accepted theory of spiral-galaxy structure
(C) compare and contrast the roles of clouds of gas and dust in two theories of spiral-galaxy structure
(D) describe a new theory of spiral-galaxy structure and contrast it with the most widely accepted theory
(E) describe a new theory of spiral-galaxy structure and discuss a reason why it is inferior to the most widely accepted theory
8. The passage implies that, according to the new theory of spiral-galaxy structure, a spiral galaxy can be created by supernovas when the supernovas are
(A) producing an underlying density wave
(B) affected by a density wave of spiral form
(C) distributed in a spiral pattern
(D) located in the central plane of a galaxy
(E) located in a differentially rotating galaxy
9. Which of the following, if true, would most discredit the new theory as described in the passage?
(A)The exact mechanism by which a star becomes a supernova is not yet completely known and may even differ for different stars.
(B) Chains of star-forming regions like those postulated in the new theory have been observed in the vicinity of dense clouds of gas and dust.
(C) The most massive stars formed from supernova explosions are unlikely to evolve into supernovas.
(D) Computer simulations of supernovas provide a poor picture of what occurs just before a supernova explosion.
(E) A density wave cannot compress clouds of gas and dust to a density high enough to create a star.
7. D 8.E 9.C
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