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第1段
1 .<-NARRATOR:->Now listen to part of a lecture on the topic you just read about.
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第2段
1 .<-FEMALE PROFESSOR:->The passage claims that there will be fewer and fewer birds, but the arguments used to support this claim are unconvincing.
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第3段
1 .First, it’s true that urban growth has been bad for some types of birds, but urban development actually provides better and larger habitats for other types—so much so that city and suburban dwellers often complain about increased bird populations: seagulls at land fills, pigeons on the streets, and so on.
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2 .Even birds like hawks and falcons can now be found in cities, where they prey on the increasing populations of pigeons and rodents.
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3 .So it’s not going to be a story of uniform decline of bird populations in the future—some populations may shrink but others will grow.
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第4段
1 .As for agriculture—it’s true that it too will increase in the future—but not in the way assumed by the reading passage.
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2 .The truth is, in the United States less and less land is being used for agriculture every year.
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3 .Increases in agricultural production have resulted from, and will continue to result from, the introduction of new, more productive varieties of crops.
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4 .These new crops produce more food per unit of land, and as a result there’s no need to destroy wilderness areas.
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第5段
1 .Third, while it’s certainly true that traditional pesticides have been destructive to birds, it’s incorrect to project this history into the future.
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2 .Now that people are aware of the possible consequences of traditional pesticides, two changes have occurred: first, new and much less toxic pesticides are being developed and that’s important.
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3 .Second, and perhaps more importantly, there is a growing trend to develop more pest-resistant crops—crops that are genetically designed to be unattractive to pests.
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4 .Pest-resistant crops greatly reduce the need for chemical pesticides, and best of all, pest-resistant crops don’t harm birds at all.
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