以下是老gre阅读题：
As of late 1980s, 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 planet-wide 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.
1. 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. comparing points of view
2. 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
3. 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?
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 clouds?
E. What proportion of the clouds in the atmosphere form over land masses?
P40
1
As of late 1980s, neither theorists nor large-scale computer climate models could accurately predict whether cloud systems would help or hurt a warming globe.
1980 年代末，无论气象理论学家还是大规模计算机气象模型都无法精确预测，云对地球暖化效应发挥积极或消极作用。
2
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 planet-wide temperature increase.
有些研究认为，海上的层积云增加 4%，可以抵消大气中二氧化碳翻倍的影响，进而阻止全球气温上升带来的潜在危害。
3
On the other hand, an increase in cirrus clouds could increase global warming.
另一方面，卷云变多则可能加剧暖化。
4
That clouds represented the weakest element in climate models was illustrated by a study of fourteen such models.
十四种模型算法显示，云是气象模型中呈现得最不成功的因素。
5
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.
假如把现在的大气二氧化碳水平加倍，比较预报结果，研究者们发现，如果不考虑云的因素，各种模型预报结果相当接近。
6
But when clouds were incorporated, a wide range of forecasts was produced.
但如果考虑云，预报结果就变得大相径庭。
7
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.
这种差异困扰着模拟结果，科学家们无法轻易预测世界气候变化的速度，也不知道那些地区面临更严重的干旱或更致命的雨季。
1. 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. comparing points of view
选 B
statement 即句 1 内容，科学家和大型计算机都搞不定云在气候中发挥的作用。
2. 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
选 C
综合句 5 - 6：
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.
不考虑云的因素，预测结果差不多 agreed quite well，加入云的因素，预测结果变得 wide range 。所以我们可以 infer，问题出在云。
3. 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?
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 clouds?
E. What proportion of the clouds in the atmosphere form over land masses?
选 A
题干中出现了 in / of / from / about the passage，答案都在文章里找。
文中出现了两种云。
stratocumulus clouds(句 2)，抵消二氧化碳，阻止变暖;
cirrus clouds(句 3)加剧变暖。
想知道云对气候的影响，要先搞清楚会产生哪种云(或比例多少)，才能进一步估计它们发挥的作用。