单项选择题

World leaders met recently at United Nations headquarters in New York City to discuss the environmental issues raised at the Rio Earth Summit in 1992. The heads of state were supposed to decide what further steps should be taken to halt the decline of Earth’s life-support systems. In fact, this meeting had much the flavour of the original Earth Summit. To wit: empty promises, hollow rhetoric, bickering between rich and poor, and irrelevant initiatives. Think U.S. Congress in slow motion. The word "deforestation" in paragraph 3 means
[A] forest damage caused by pollution.
[B] moving population from forest to cities.
[C] the threat of climate change.
[D] cutting large areas of trees.

Almost obscured by this torpor is the fact that there has been some remarkable progress over the past five years—real changes in the attitude of ordinary people in the Third World toward family size and a dawning realisation that environmental degradation and their own well-being are intimately, and inversely, linked. Almost none of this, however, has anything to do with what the bureaucrats accomplished in Rio.
Or it didn’t accomplish. One item on the agenda at Rio, for example, was a renewed effort to save tropical forests. (A previous UN-sponsored initiative had fallen apart when it became clear that it actually hastened deforestation.) After Rio, a UN working group came up with more than 100 recommendations that have so far gone nowhere. One proposed forestry pact would do little more than immunizing wood-exporting nations against trade sanctions.An effort to draft an agreement on what to do about the climate changes caused by CO2 and other greenhouse gases has fared even worse. Blocked by the Bush Administration from setting mandatory limits, the UN in 1992 called on nations to voluntarily reduce emissions to 1990 levels. Several years later, it’s as if Rio had never happened. A new climate treaty is scheduled to be signed this December in Kyoto, Japan, but governments still cannot agree on these limits. Meanwhile, the U.S. produces 7% more CO2 than it did in 1990, and emissions in the developing world have risen even more sharply. No one would confuse the "Rio process" with progress.
While governments have dithered at a pace that could make drifting continents impatient, people have acted. Birth-rates are dropping faster than expected, not because of Rio but because poor people are deciding on their own to reduce family size. Another positive development has been a growing environmental consciousness among the poor. From slum dwellers in Karachi, Pakistan, to colonists in Rondonia, Brazil, urban poor and rural peasants alike seem to realize that they pay the biggest price for pollution and deforestation. There is cause for hope as well in the growing recognition among business people that it is net in their long-term interest to fight environmental reforms. John Browne, chief executive of British Petroleum, boldly asserted in a major speech in May that the threat of climate change could no longer be ignored.
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单项选择题
Which of the following statements is true [A] Archaeopteryx’s top ground speed when running was fast enough for liftoff. [B] It is most important for Archaeopteryx to take to the air by designing its fans and blowers. [C] The bird’s wings would have provided velocity for takeoff by beating the air in different angles. [D] The bird could fly because its wings could act like an airplane’s wings at the beginning of its run.
A running start This could have helped a bird like Archaeopteryx into the air, but its estimated top ground speed wasn’t anywhere near fast enough for liftoff. Chiappe teamed with industrial aerodynamicist Phillip Burgers, who spends his days designing fans and blowers, and just happens to have earned a Ph. D. studying avian flight. The two used aerodynamic theory and biomechanics to re-create the takeoff run of Archaeopteryx. During a run, the researchers found, the bird’s wings were able to rotate by 45 degrees at the shoulder, angled forward like two large oars beating the air. That may have provided the extra burst of speed Archaeopteryx needed to outrun hungry predator or snap up a quick-running lizard. And, the new calculations show, it would also have generated sufficient velocity for takeoff. During the early phase of a run, Burgers explains, Archaeopteryx’s wings acted more like an airplane’s engines than its wings, providing more thrust than lift. Then, once in the air, Archaeopteryx would have rotated its wings back to horizontal, to maintain altitude. Burgers holds that modern birds do exactly the same thing. Why did no one notice until now "We’re infatuated with lift," says Burgers, "because we can’t generate it ourselves. "Chiappe and Burgers have shown that Archaeopteryx could have taken off from the ground, but whether or not it actually did may never be known. "I don’t really care if Archaeopteryx flew or not," says Burgers. After all, people still ask the same question about chickens. "Does a chicken fly Maybe, maybe not. ’But its wings help it get where it needs to go. Flying, it turns out, is just the continuation of running by other means.