最新预测：英语六级新题型试卷（十）

Passage 3
A classic series of experiments to determine the effects of overpopulation on communities of rats was conducted by a psychologist, John Calhoun. In each experiment, an equal number of male and female adult rats were placed in an enclosure. The rat populations were allowed to increase. Calhoun knew from experience approximately how many rats could live in the enclosures without experiencing stress due to overcrowding. He allowed the population to increase to approximately twice this number. Then he stabilized the population by removing offspring that were not dependent on their mothers. At the end of the experiments, Calhoun was able to conclude that overcrowding causes a breakdown in the normal social relationships among rats, a kind of social disease. The rats in the experiments did not follow the same patterns of behavior as rats would in a community without overcrowding.
The females in the rat population were the most seriously affected by the high population density. For example, mothers sometimes abandoned their pups, and, without their mothers’ care, the pups died. The experiments verified that in overpopulated communities, mother rats do not behave normally. Their behavior may be considered diseased, pathological (病理学的).
The dominant males in the rat population were the least affected by over population. Each of these strong males claimed an area of the enclosure as his own. Therefore, these individuals did not experience the overcrowding in the same way as the other rats did. However, dominant males did behave pathologically at times. Their antisocial behavior consisted of attacks on weaker male, female, and immature rats. This deviant behavior showed that even though the dominant males had enough living space, they too were affected by the general overcrowding.
Non-dominant males in the experimental rat communities also exhibited deviant social behavior. Some withdrew completely, avoiding contact with other rats. Other non-dominant males were hyperactive, chasing other rats and fighting each other.
The behavior of the rat population has parallels in human behavior. People in densely populated areas exhibit deviant behavior similar to that of the rats in Calhoun's experiments. In large urban areas, such as New York City, London, and Cairo, there are abandoned children. There are cruel, powerful individuals, both men and women. There are also people who withdraw and people who become hyperactive. Is the principal cause of these disorders overpopulation? Calhoun's experiments suggest that it might be. In any ease, social scientists and city planners have been influenced by the results of this series of experiments.
31. Calhoun stabilized the rat population ____.
A) when it was double the number that could live in the enclosure without stress
B) by removing young rats
C) so that there was a constant number of adult rats in the enclosure
D) All of the above are correct
32. Which of the following inferences can NOT be made from the first paragraph?
A) Calhoun’s experiment is still considered important today.
B) Overpopulation causes pathological behavior in rat populations.
C) Stress does not occur in rat communities unless there is overcrowding.
D) Calhoun had experimented with rats before.
33. According to the passage, which of the following is NOT true?
A) Dominant males had adequate living space.
B) Dominant males were not as seriously affected by overcrowding as the other rats.
C) Dominant males attacked weaker rats.
D) The strongest males are always able to adapt to bad conditions.
34. The author implies that the behavior of the dominant male rats is sometimes parallel with
that of _____.
A) cruel, powerful people
B) people who abandon their children
C) hyperactive people
D) people who would like to keep to themselves.
35. The main point of this passage is that _______.
A) although rats are affected by overcrowding, people are not
B) overcrowding may be an important cause of social pathology
C) the social behavior of rats is seriously affected by overcrowding
D) Calhoun's experiments have influenced many people

Passage 4
In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming: in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.
Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warm the earth.
However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude, therefore, that up to now natural influences on the weather have exceeded those caused by man. The question is: which natural cause has most effect on the weather?
One possibility is the variable behavior of the sun. astronomers at one research station have studied the hot spots and “cold” spots (that is, the relatively less hot spots) on the sun. as the sun rotated, every 27.5 days, it presents hotter or “colder” faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth’s atmospheric pressure, and consequently on wind circulation. The sun is also variable over a long term: its heat output goes up and down in cycles, the latest trend being downward.
Scientists are now finding mutual relations between models of solar-weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia of the earth’s climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful counter-balance to the sun’s diminishing heat.
36. Experts used to believe that the chief reason for global warming is______.
A) that most fuel is consumed in the northern hemisphere
B) human activities
C) natural influences and carbon dioxide
D) the solar energy
37. The article is written to illustrate ______.
A) the greenhouse effect
B) the solar effects on the earth
C) the models of solar-weather interactions
D) the factors responsible for the global climate
38. In spite of the greater consumption of fuel in the northern hemisphere, temperatures seem to be falling. This is_____.
A) possibly because of the melting of the ice caps in the poles
B) mainly because the levels of carbon dioxide are rising
C) partly due to the variations of the output of solar energy
D) because the sun presents its “colder” face to the earth
39. On the basis of the models, scientists are of the opinion that ______.
A) the climate of the world should be becoming cooler
B) it’ll take thousands of years for the inertia of the earth’s climate to take effect
C) the man-made warming effect helps to increase the solar effects
D) the new Ice Age will be delayed by the greenhouse effect
40. If the assumption about the delay of a new Ice Age is correct _______.
A) the increased levels of carbon dioxide will warm up the earth even more quickly
B) the greenhouse effect will work to the advantage of the earth
C) the best way to overcome the cooling effect will be to burn more fuels
D) ice will soon cover the northern hemisphere