考研英语阅读命题思路透析和真题揭秘(43)

When prehistoric man arrived in new parts of the world, something strong happened to the large animals; they suddenly became extinct. Smaller species survived, the large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.

That the seas are being over-fished has been known for years what researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing. They have looked at half a century of data from fisheries around the world. Their methods de not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time. According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) inanes fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then.

Dr. Worm acknowledges that these figures are conservative, one reason for this is that fishing technology has improved Today's vessels can find their prey using satellites and sonar, which were not available 50 years ago that means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes. In the early days, too, longlines would have been more saturated with fish. Some individuals would therefore not have been caught, since to baited hooks would have been available to trap them, leading to an underestimate of fish stocks in the past. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around noise.

Dr. Myers and Dr. worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the date support an idea current among marine biologists, that of the "shifting baseline". The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past. That matters because theory suggests that the maximum sustainable yield that can be cropped form a fishery comes when the biomass of a target species is about 50% of its original levels. Most fisheries are well below that, which is a bad way to de business.

31.The extinction of large prehistoric animals is noted to suggest that
[A] large animal were vulnerable to the changing environment
[B] small species survived as large animals disappeared
[C] large sea animals may face the same threat today.
[D] Slow-growing fish outlive fast-growing ones

[答案] C

[解题思路]

本题要求判断史前大型动物的灭绝这个例子所暗示的内容。乍一看似乎四个选项都各有道理，因此我们要定位原文信息。文章第一段主要介绍了这些大型动物灭绝的原因，同时该段最后一句话指出"Now something similar could be happening in the oceans"（现在同样的事情可能正在海洋中发生），也就是说，现在海洋中的大型动物也正面临着史前大型动物曾经面临的威胁。因此文章开篇是通过类比手法来引出主题，C选项符合题意。A、B、D都不符合第一段中提供的信息。

[题目译文]

文中通过史前大型动物的灭绝是想说明
[A] 大型动物在环境发生变化的时候更容易受到伤害
[B] 随着大型动物的灭绝，小型动物却生存了下来
[C] 大型海洋动物现在可能面临同样的威胁
[D] 生长缓慢的鱼类比生长快速的鱼类活得更久

32. We can infer form Dr Myers and Dr. Worm's paper that
[A] the stock of large predators in some old fisheries has reduced by 90%
[B] there are only half as many fisheries are there were 15 years ago
[C] the catch sizes in new fisheries are only 20% of the original amount
[D] the number of larger predators dropped faster in new fisheries than in the old

[答案] A

[解题思路]

文章第二段最后两句话说"According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) inanes fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then"（根据他们最近在《自然》杂志上发表的文章，在一个新渔场中大型食肉海洋生物（一种杀死并吃掉其它动物的生物）的总量在15年的时间里平均减少了80%。而在一些大型的捕鱼场，这个数字又进一步减半）。15年平均减少了80%，15年之后又减少了一半，（也就是20%中的10%），加起来是90%，因此正确答案是A。B、C选项明显不正确。但是D选项有很强的干扰性，因为该选项从某种意义上来说是正确的，但是没有A选项的表述具体和精确。

[题目译文]

我们可以从Myers和Worm博士的论文中推断出
[A] 在一些老渔场，大型肉食鱼类的数量减少了90%
[B] 现在的渔场数量只是15年前的一半
[C] 新渔场的捕鱼量只有原来的20%
[D] 新渔场大型肉食鱼类的数量下降比老渔场快