今天小编给大家带来了关于托福英语的知识点分享，希望对大家的英语学习有所帮助，预祝大家考试高分通过。迎上风雨，勇敢面对，相信走过风雨后，彩虹的美丽就在前方的风景处等你。早晨那缕缕充满希望的阳光，是我们前进的动力，是我们坚强不屈的毅力。
词汇：predator 捕食者，天敌
Well, ongoing investigations have revealed that predator is the most likely cause of sea otter decline after all.
显然，针对阅读首段提到的两种可能性，lecturer是倾向于天敌捕猎的理论。
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 an otter is killed by a predator, it's eaten immediately so it can't wash up on shore.
污染理论弱于解释，sea otter的尸体呢，如果是由污染致死的，沿岸应该有尸体的,真是因为被捕食者吃了，才导致沿岸见不到尸体。
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.

Orcas捕食的鲸鱼为人类所杀，所以它可能已经开始吃小的东西了。海狮等的减少可能就是，跟sea otter一样，被虎鲸所捕杀
词汇：orcas，虎鲸
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.
不均衡性是因为浅湾、礁石等地虎鲸进入不了，它能进入的地方sea otter等都明显减少了