来源：新航道 浏览：0 发布日期：2014-08-01 14:57
The lecturer argues against the three measures mentioned in the reading passage to reduce the population of the cane toad, a species introduced to the Australian continent.
The lecturer argues that the first measure, a national fence, would not prevent the flow of streams or rivers and, therefore, would allow young toads or toad eggs to travel to the other side of the fence. The reading passage, however, argues that such a fence would effectively cut off the Route that animals use to establish colonies and expand in population.
Regarding the second measure, recruiting a large group of volunteers, the lecturer explains that volunteers often have difficulty distinguishing between cane toads and native frogs, an endangered species. Therefore, volunteers might kill members of both species. The Reading passage gives the opposite view. Organizing a large group of volunteers to join an extermination campaign would speed the destruction of cane toads.
Finally the lecturer objects to the third measure—using an infectious virus. She points out that a virus intended to eliminate Australia’s cane toad population could be transmitted through animal transportation to other continents where cane toads are an essential part of the ecosystem. This is indirect contradiction with the claim in the reading passage that an infectious virus could be developed to stop the reproduction of cane toads without harming other species.
The reading passage suggests that three pieces of evidence provide support that a portrait recently commissioned for sale by a member of Jane Austen’s family is of Jane Austen herself when she was a teenager. However, the lecturer rejects such evidence and argues that the painting could not be a portrait of Jane Austen.
First, the lecturer argues that the portrait was approved for publication by the Austen family 70 years after Jane Austen’s death, suggesting that members of her extended family might have published the portrait without having actually seen her in person. Therefore. the fact that the portrait had been endorsed by her family members does not necessarily prove that it is a portrait of Jane Austen.
Second, the lecturer argues that the resemblance between the portrait and an authentic sketch of the adult Jane Austen could be explained by the hypothesis that the portrait is of a relative of Jane Austen when the relative was a teenager.
Finally, the lecturer argues that despite the style of the painting, which links it to the exact period when Jane Austen was a teenager, the stamp on the back of the canvas suggests that the portrait was painted at least 27 years after Jane Austen’s birth, indicating that the portrait was of someone else who was much older than the teenage Jane Austen.
The lecturer and the reading passage suggest two competing theories, the predation theory vs. the pollution theory, to explain why the sea otter population is in rapid decline.
The professor reasons that the absence of dead sea otters washed up the coast suggests that their decline is not caused by sea pollution but rather by sea predators who consume their bodies after Killing them. In contrast, the reading passage attributes the death of sea otters to pollution, citing evidence of increased sources of ocean contaminants which lead to greater vulnerability to infections.
Furthermore, the lecturer argues that orcas are likely factors in the disappearance of sea otters, because the scarcity of whales, their usual prey, has left them with no other choice but to start hunting smaller mammals like the otters for food. The reading passage, on the other hand, Rules out this theory based on the orca’s preying habit, and instead approves of the pollution theory as the only explanation for the decline op both large and small sea mammals across the entire ecosystem.
Finally, according to the lecturer, the uneven pattern of sea otter decline corresponds to the distribution of the orcas. She argues that the pact that their population has declined most rapidly where orcas are most prevalent further validates the predation theory. However, the reading passage argues that changeable environmental factors, which lead to different concentrations of pollutants, better explains the varying pattern of sea otter decline.