题目内容

We need to know something about the structure and operation of science because ______.

A. it is not easy to understand, the things that excite and frustrate the scientists
B. science affects almost every aspect of our life
C. scientists live in a specific substructure
D. it is easier to understand general characteristics of science

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The passage suggests that a large decrease in the amount of CO2 in the atmosphere would result in ______.

A. at least a slight decrease in global temperatures
B. at most a slight increase in short wavelength radiation reaching the Earth
C. a slight long-term increase in global temperatures
D. a slight short-term increase in global temperatures

Which of the followings is NOT mentioned as a way against traffic accidents?

A. build more highways
B. stricter driving tests
C. test drivers every three years
D. raise age limit and lay down safety specifications

In the last few minutes the conversation has become seemingly ______ as if the discussion

A. crucial
B. central
C. casual
D. causal

The level of carbon dioxide, CO2, in the atmosphere has an important effect on climatic change. Most of the Earth's incoming energy is short wavelength radiation, which tends to pass through atmospheric CO2 easily. The Earth, however, reradiates much of the received energy as a long wavelength radiation, which CO2 absorbs and then remits toward the Earth. This phenomenon, known as the greenhouse effect, can result in an increase in the surface temperature of a planet. An extreme example of the effect is shown by the Venus, a planet covered by heavy clouds composed mostly of CO2, whose surface temperatures have been measured at 430℃. If the CO2 content of the atmosphere is reduced, the temperature falls. According to one respectable theory, if the atmospheric CO2 concentration were halved, the Earth would become completely covered with ice. Another equally respectable theory, however, states that a halving of the CO2 concentration would lead only to a reduction in global temperatures of 3℃. If, because of an increase in forest fires or volcanic activities, the CO2 content of the atmosphere increased, a warmer climate would be produced. Plant growth, which relies on both the warmth and the availability of CO2, would probably increase. As a consequence, plants would use more and more CO2. Eventually CO2 levels would diminish and the climate, in turn, would become cooler. With reduced temperatures many plants would die; CO2 would thereby be returned to the atmosphere and gradually the temperatures would rise again. Thus, if this process occurred, there might be a long-term oscillation in the amount of CO2 present in the atmosphere, with regular temperature increases and decreases of a set magnitude.
Some climatologists argue that the burning of fossil fuels has raised the level of CO2 in the atmosphere and has caused a global temperature rise of at least 1℃. But a supposed global temperature rise of 1℃ may in reality be only several regional temperature increases, restricted to areas where there are many meteorological stations and caused simply by shifts in the pattern of atmospheric circulation. Other areas, for example, the Southern Hemisphere oceanic zone, may be experiencing an equivalent temperature decrease that is unrecognized because of the shortage of meteorological recording stations.
Which of the following questions does the passage supply information for answering?

A. Why are projections of the effects of changes in water vapor levels on the climate so inaccurate?
B. What are the steps in the process that takes place as CO2 absorbs long wavelength radiation?
C. How might our understanding of the greenhouse effect be improved if the burning of fossil fuels were decreased?
D. What might cause a series of regular increases and decreases in the amount of CO2 in the atmosphere?

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