综合写作10
Reading
The sea otter is a small mammal that lives in waters along the western coast of North America from California to Alaska. When some sea otter populations off the Alaskan coast started rapidly declining a few years ago, it caused much concern because sea otters play an important ecological role in the coastal ecosystem. Experts started investigating the cause of the decline and quickly realized that there were two possible explanations: environmental pollution or attacks by predators. Initially, the pollution hypothesis seemed the more likely of the two.
The first reason why pollution seemed the more likely cause was that there were known sources of it along the Alaskan coast, such as oil rigs and other sources of industrial chemical pollution. Water samples from the area revealed increased levels of chemicals that could decrease the otters' resistance to life-threatening infections and thus could indirectly cause their deaths.
Second, other sea mammals such as seals and sea lions along the Alaskan coast were also declining, indicating that whatever had endangered the otters was affecting other sea mammals as well. This fact again pointed to environmental pollution, since it usually affects the entire ecosystem rather than a single species. Only widely occurring predators, such as the orca (a large predatory whale), could have the same effect, but orcas prefer to hunt much larger prey, such as other whales.
Third, scientists believed that the pollution hypothesis could also explain the uneven pattern of otter decline: at some Alaskan locations the otter populations declined greatly, while at others they remained stable. Some experts explained these observations by suggesting that ocean currents or other environmental factors may have created uneven concentrations of pollutants along the coast.
Listening
Professor:
Well, ongoing investigations have revealed that predation is the most likely cause of sea otter decline after all. Well, ongoing investigations have revealed that predation is the most likely cause of sea otter decline after all.
First, the pollution theory is weakened by the fact that no one can really find any dead sea otters washing off on Alaskan beaches. That's not what you would expect if infections caused by pollution started killing a lot of otters. On the other hand, the fact that it's so hard to find dead otters is consistent with the predator hypothesis. If another is killed by a predator, it's eaten immediately so it can't wash up on shore.
Second, although orcas may prefer to hunt whales, whales have essentially disappeared from the area because of human hunters. That means that orcas have had to change their diet to survive and since only smaller sea mammals are now available, orcas have probably started hunting those. So it probably is the orcas that are causing the decline of all the smaller sea mammals mentioned in the passage - the seals, the sea lions and the sea otters.
And third, the uneven pattern of otter decline is better explained by the orca predation theory than by the pollution theory. What happens to otters seems to depend on whether the location where they live is accessible to orcas or not. In those locations that orcas can access easily, the number of sea otters has declined greatly. However, because orcas are so large, they can't access shallow or rocky locations. And shallow and rocky locations are precisely the types of locations where sea otter populations have not declined.
一、阅读听力要点概括
Reading Passage
Main points: 2 explanations for the decline for sea otter and pollution seemed better.
Sub point 1: Source of pollution along the Alaskan coast.
Sub point 2: Other sea mammals also declining by pollution.
Sub point 3: Pollution could explain the uneven otter decline.
Lecture
Attitude: Against, predation is most likely to be the reason.
Sub Point 1: No dead sea otters washing off on beaches. (Eaten immediately.)
Sub Point 2: Orcas now eat sea mammals. ( Decline of all smaller sea mammals.)
Sub Point 3: Otters decline where orcas can access. Otter not decline at rocky locations.
Answers
二、范文逐段赏析
Paragraph 1
The lecturer and the reading passage suggest two competing theories to explain why the sea otter population is in rapid decline: the predation theory and the pollution theory.
此段功能：
(Listening passage后文提到用L代替)
(Reading passage后文用R代替)
作者先总结了有两种原因造成水獭otter下降，R和L各支持一种。
此段结构：
开头段说明L和R各持一个意见，准备开始讨论。
Paragraph 2
The professor reasons that the absence of dead sea otters washed up on the coast suggests that their decline is not caused by sea pollution but rather by sea predators that 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 animal infections.
此段功能：
以L为主，先陈述L的事实：海滩上从未发现有死otter意味着其实他们都被掠食者吃掉了。在R里，R仅认为数量降低是因为污染物。
此段结构：
此段为分分结构，作者把双方证据一对比，发现R有一些局限性和考虑问题的不全面。
Paragraph 3
Furthermore, the lecturer argues that orcas are likely factors in the disappearance of sea otters. Because of the scarcity of whales, the usual prey, has left orcas no other choice but to hunt smaller mammals for food. The reading passage, on the other hand, rules out this theory based on the orcas’ preying habits, and instead promotes the pollution theory as the only explanation for the decline of both large and small sea mammals across the entire ecosystem.
此段功能：
第二点论证中，L认为逆戟鲸(orcas)要对otters的消失负责。因为其他鲸类的减少，orcas只能去扑食小哺乳动物。R觉得orcas只食鲸类就排除了orcas的责任，认为污染物的集中是唯一造成大小哺乳动物死亡的原因。
此段结构：
此段还是分分结构，两种现象一对比， R有了先入为主的概念，考虑不一定周全。
Paragraph 4
Finally, according to the lecturer the uneven pattern of sea otter decline corresponds to the distribution of the orcas. She argues that the fact 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 distributed pattern of sea otter decline.
此段功能：
在最后对于不均匀的otters减少的原因的讨论中。L指出，在orcas容易聚集的地方，otters数量降低明显，证明了扑食理论。R说，由于环境因素，不同程度的污染沉积更好的解释了otters下降不均匀。
此段结构：
最后一点上，L和R各持一方理由。作者很客观完整了呈现了双方理由，没有因为自己喜好谁的理由就偏向一边。
三、范文全篇总评
1、 逻辑结构
全文遵从总分结构，开头段直接一句话总结+逻辑，展开全文对攻基调。
在三个论段里，作者公正了重述了双方证据论点，强烈的表达了L和R的对抗情绪，但是并没有分出L和R谁更正确。
2、语言表达
文章论段十分对称，作者平淡客观罗列双方对应证据，其中可以借鉴的词句有：
1. Attributes:把….归于
/Ascribe/
Success can be attributes to hard work and a little good luck.
2. Contaminant：污染物
/Pollutant/
The metal contaminant in this sample is way beyond standard.
3. Scarcity: 缺乏
/Lack/Shortage/
High price is often a signal of scarcity.