题目内容
Which of the followings is NOT mentioned as a way against traffic accidents？
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In the last few minutes the conversation has become seemingly ______ as if the discussion
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？
The author refers to the Venus primarily in order to ______.
It is not difficult to gain general agreement that man -induced increases in the endangerment and extinction of wildlife whether due to habitat alteration or loss, pollution, insufficiently regulated hunting, or other factors are undesirable. It is, however, more difficult to obtain consensus when consideration is given to the economic costs of correcting such trends, including natural habitat preservation, regulation of pesticides and other toxic substances, and wildlife and park management. Endangered species often are, in effect, competitors with humans for habitat and other resources which also provide other kinds of human use and need.
Measures needed to protect endangered species vary considerably in difficulty and cost. Of the approximately 400 inverterate species which at present appear to be threatened, for example, about one third could probably be restored by such inexpensive means as modifying the boundaries of designated natural are as, acquiring and protecting caves and other small areas which contain the particular species, and additional management 'of parks and refuges.
Another one - third of the endangered lower animal species are threatened principally by water pollution and could be protected by improved control, particularly of five southern rivers.
The remaining one - third of the 400 endangered shellfish species would be considerably more difficult to protect. These are threatened by complex factors, such as overcollecting, channelization, highway and housing development, clams introduced species such as the Asian snail, dredging, quarry washing, poor erosion control, and lowering of water table.
The identification of threatened species and other significant wildlife trends must precede any corrective measures, and our knowledge base for making such identification is deficient in many respects. Our present lists of threatened species and subspecies are known to be incomplete, except in those geographical areas which contain habitats of species that have important commercial or sports harvest value.
Which of the followings is neither expressed nor implied in the passage as being a threat posed by man to wildlife preservation？
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