In the 1960s scientists begin to recognize that environmental contaminants could not only affect the health and survival of individual animals but also alter the prospects for their off-spring and thereby potentially change the genetic makeup of entire populations.
Researchers were first altered to problems in wildlife in the 40s after the populations of eagles, falcons, and the other fish-eating birds in Britain plummeted. In nest after nest the birds’ eggshells were so thin that they cracked under the weight of the adults during incubation. In the 1960s David Peakall and other wildlife toxicologists demonstrated that the accumulation of very high levels of such pesticides as DDT in the birds’ tissues had seriously impaired their productive capabilities. Some of these declines resulted in the complete disappearance of populations from large portions of their former range. In North America, for example, the eastern population of the peregrine falcon was virtua
A. prove that contaminants are harmful to health
B. show that contaminants could affect the future generations
C. describe some experiments made by toxicologists
D. urge that pesticides should be abandoned
| This line of inquiry did not begin
until earlier this month--more than three months after the accident--because
there were "too many emotions, too many egos," said retired Adm. Harold Gehman,
chairman of the Columbia Accident Investigation Board. Testifying before the Senate Commerce Committee, Gehman said this part of his inquiry Was in its earliest stages, starting just 10 days ago. But Gehman said he already has concluded it is "inconceivable" that NASA would have been unable or unwilling to attempt a rescue for astronaut, s in orbit if senior shuttle managers and administrators had known there was fatal damage to Columbia’s left wing. Gehman told reporters after the hearing that answers to these important questions could have enormous impact, since they could place in a different context NASA’s decisions against more aggress A. have managed the rescue of the astronauts orbiting the earth B. still have been unable to conceive of any way to save the astronauts C. have attempted to help the astronauts out of danger unwillingly D. have succeeded in repairing the damaged left wing of the shuttle [单项选择]
{{B}}TEXT E{{/B}} Learning for Its Own Sake For me, scientific knowledge is divided into mathematical sciences, natural sciences or sciences dealing with the natural world (physical and biological sciences), and sciences dealing with mankind (psychology, sociology, all the sciences of cultural achievements, every kind of historical knowledge). Apart from these sciences is philosophy, about which we will take shortly. In the first place, all this is pure or theoretical knowledge, sought only for the purpose of understanding, in order to fulfill the need to understand that is intrinsic and consubstantial to man. What distinguishes man from animal is that he knows and needs to know. If man did not know that the world existed, and that the world was of a certain kind, that he was in the world and that he himself was of a certain kind, he wouldn’ t be a man. The technical aspects of applications of k A. invented modern mathematical applications B. were interested in navigation C. were unaware of the value of their studies D. worked with electricity [单项选择]
{{B}}TEXT B{{/B}} Countries at all levels of economic development face a similar challenge: to make their industries competitive in an increasingly integrated global economy. Despite sharing the same overall goal, though, countries face distinctive geographical issues in ensuring that their industries compete effectively. Industries in relatively developed countries must protect their markets from new competitors. Countries once governed or still governed by communist parties must prepare their industries to compete in a global market-driven economy. Developing countries of Africa, Asia, and Latin America must identify new markets and sources of revenue to generate industrial growth. Competition among blocs Industrial competition in the relatively developed world increasingly takes place among blocs of countries. Countries within three groups—North America, Western Europe, and East Asia—cooperate more extensively with each o A. All of them have their headquarters in North America. B. Labor is an important factor in determining the sites of factories to be built. C. The Japanese have built their plants primarily along the coasts of the U. S. D. Goods manufactured in local plants are viewed as imports in some countries. 我来回答: 提交
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