敏感词
the tendency of orchestral musicians to employ their most brilliant effects in the early movements of symphonies composed by mozart and beethoven.
“反”型错误
book 1, reading 3, p69
the human species came into being at the time of the greatest biological diversity in the history of the earth. today, as（原因） human populations expand and alter the natural environment, they are reducing biological diversity to its lowest（敏感词） level since the end of the mesozoic era, 65 million years ago. the ultimate consequences（结果） of this biological collision are beyond calculation, but they are certain to be harmful（负评价）, that, in essence, is the biodiversity crisis.
the history of global diversity can be summarized as follows: after the initial flowering of multicellular animals, there was a swift rise in the number of species in early paleozoic times (between 600 and 430 million years ago), then plateaulike stagnation¹ for the remaining 200 million years of the paleozoic era, and finally a slow but steady climb through the mesozoic and cenozoic eras to diversity's all-time high. this history suggests that biological diversity was hard won and a long time in coming.
furthermore, this pattern of increase was set back by five massive extinction² episodes, the most recent of these, during the cretaceous period, is by far the most famous, because（→） it ended the age of the dinosaurs³, conferred hegemony on the mammals, and ultimately made possible the ascendancy⁴ of the human species. but the cretaceous crisis was minor⁵（比较词） compared with the permian extinctions 240 million years ago,（p>c） during which between 77 and 96 percent of marine⁶ animal species perished. it took 5 million years, well into mesozoic times, for species diversity to begin a significant recovery. （有很多数字连续出现不必读，不过是对上文的支持）
within the past 10,000 years biological diversity has entered a wholly new era. human activity has had a devastating⁷（负评价） effect on species diversity, and the rate of human-induced extinctions is accelerating. （half of the bird species of polynesia have been eliminated through hunting and the destruction of native forests. ）（hundreds of fish species endemic to lake victoria are now threatened with extinction following the careless introduction of one species of fish, the nile perch⁸. ）（例子）the list of such bio geographic⁹ disasters is extensive. （评价，凡是在关于自然、生物的文章中有人出现，往往是负评价）
because every species is unique and irreplaceable, the loss of biodiversity is the most profound process of environmental change. its consequences（→） are also the least predictable because the value of earth's biota¹⁰ (the fauna¹¹ and flora¹² collectively) remains¹³ largely unstudied and unappreciated, unlike（≠） material and cultural wealth, which we understand because they are the substance of our everyday lives. biological wealth is usually taken for granted. this is a serious strategic error（负评价）, one that will be increasingly regretted（负评价） as time passes. the biota is not only part of a country's heritage, the product of millions of years of evolution centered on that place; it is also a potential source for immense untapped material wealth in the form of food, medicine, and other commercially important substance. （文章最后四五行可略读，如出现的是重复性的内容，飞速掠过，但如在倒数第二段之前出现强转折，则必须注意）
7. which one of the following best expresses the main idea of the passage?
the reduction in biodiversity is an irreversible process that represents a setback¹⁴ both for science and for society as a whole.
the material and cultural wealth of a nation are insignificant¹⁵ when compared with the country's biological wealth.
the enormous diversity of life on earth could not have come about without periodic extinctions that have conferred preeminence¹⁶ on one species at the expense of another.
the human species is in the process of initiating¹⁷ a massive extinction episodes look minor by comparison.
the current decline in species diversity is human-induced tragedy of incalculable proportions that has potentially grave consequences for the human species.
8. which one of the following situations is most analogous¹⁸ to the history of global diversity summarized in lines 10-18 of the passage?
the number of fish in a lake declines abruptly¹⁹ as a result of water pollution. then makes a slow comeback after cleanup efforts and the passage of ordinances²⁰ against dumping.
the concentration of chlorine in the water supply of large city fluctuates widely before stabilizing²¹ at a constant and safe level.
an old-fashioned article of clothing goes in and out of style periodically as a result of features in fashion magazines and the popularity of certain period films.
after valuable mineral deposits are discovered, the population of a geographic region booms then levels off an d begins to decrease at a slow and steady race.
the variety of styles stocked by a shoe store increases rapidly after the store opens, holds constant for many months, and then gradually creeps upward.
9. the author suggests which one of the following about the cretaceous crisis?
it was the second most devastating extinction episode in history.
it was the most devastating extinction episode up un until that time.
it was less devastating to species diversity than is the current biodiversity crisis.
the rate of extinction among marine animal species as a result of the crisis did not approach 77 percent.
(e) the dinosaurs comprised the great majority of species that perished during the crisis

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