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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 .The cane toad won’t be as easy to get rid of as the reading suggests.
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2 .The measures proposed by the reading are likely either to be unsuccessful or to cause unwanted environmental damage.
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第3段
1 .First of all, a national fence probably won’t stop the spread of the toad.
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2 .That’s because young toads and toad eggs are found in rivers and streams.
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3 .No matter where the fence is located, at some point there will be rivers or streams flowing from one side to the other.
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4 .These waterways will be able to carry the young toads and their eggs to the other side.
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5 .Since it’s only necessary for a few young toads or eggs to get through the fence in order to establish population on the other side, the fence is unlikely to be effective.
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第4段
1 .Secondly, a massive group of volunteers could have success trapping and destroying toads.
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2 .But it’s likely that these untrained volunteers would inadvertently destroy many of Australia’s native frogs—some of which are endangered.
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3 .It’s not always easy to tell the cane toad apart from native frogs, especially when it’s young.
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第5段
1 .Third, using the virus is a bad idea because it could have terrible consequences for cane toads in their original habitat in Central and South America.
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2 .You might be wondering, how can a virus released in Australia cause harm in the Americas?
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3 .Well, Australian reptiles and amphibians are often transported to other continents, by researchers or pet collectors, for example.
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4 .Once the animals infected by the virus reach Central and South America, the virus will attack the native cane toads and devastate their populations.
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5 .That would be an ecological disaster because in the Americas, cane toads are a native species and a vital part of the ecosystem.
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6 .So if they’re eliminated, the whole ecosystem will suffer.
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