P1 The Dinosaurs Footprints and Extinction 恐龙的足迹和灭绝

P2 Food for Thought 非洲饥荒问题

P3 Human Behavior 合作行为

 

朗阁教师吴苏哲点评

1. 本次考试整体程度为中上等，其中前两篇较简单，最后一篇偏难。

2. 整体分析：涉及科学（P1）环境（P2）和社会（P3）

3. 主要题型：12月的第四场考试的考题为两旧一新，难度相对低的P1和P2都是旧题。在题型上依然延续了今年考试的重点，主流基础题型为摘要题和判断题。其中，摘要题全部体现为Summary填空题，分布于P1和P3中。判断题则保持近期一贯的两组出题风格，分别出在P1和P2。本次考试乱序题考得相对较多，体现为Heading题和人名观点配对题。Heading题出在难度相对低的P2，人名观点配对题出在相对较难的P3。与12月的第一和第三次考试相同，本次考试单选题考察得依然相对较少，仅有3题。

 

P1 The Dinosaurs Footprints and Extinction 恐龙的足迹和灭绝 （2012年11月3日旧题重现）

文章主旨：对恐龙灭绝的介绍

包含判断题6题，Summary填空题7题

参考答案：

判断题1-6：

1. False

2. False

3. NG

4. True

5. False

6. True

Summary填空题7-13：

7. ecological release

8. competitor

9. dragons

10. overlooked

11. vanished

12. swallowed up

13. Misdated

 

原文及考题参考：

The Dinosaurs Footprints and Extinction

A. Everybody knows that the dinosaurs were killed by an asteroid. Something big hit the earth 65 million years ago and, when the dust had fallen, so had the great reptiles. There is thus a nice, if ironic, symmetry in the idea that o similar impact brought about the dinosaurs’ rise. That is the thesis proposed by Paul Olsen, of Columbia University, and his colleagues in this week’s Science.

B. Dinosaurs first appear in the fossil record 230m years ago, during the Triassic period. But they were mostly small, and they shared the earth with lots of other sorts of reptile. It was in the subsequent Jurassic, which began 202million years ago, that they overran the planet and turned into the monsters depicted in the book and movie “Jurassic Park”(侏罗纪公园) . (Actually, though, the dinosaurs that appeared on screen were from the still more recent Cretaceous (白垩纪) period.) Dr Olsen and his colleagues are not the first to suggest that the dinosaurs inherited the earth as the result of an asteroid strike. But they are the first to show that the takeover did, indeed, happen in a geological eyeblink.

C. Dinosaur skeletons are rare. Dinosaur footprints are, however, surprisingly abundant. And the sizes of the prints are as good an indication of the sizes of the beasts as are the skeletons themselves. Dr Olsen and his colleagues therefore concentrated on prints, not bones.

D. The prints in question were made in eastern North America, a part of the world then full of rift valleys similar to those in East Africa today. Like the modern African rift valleys, the Triassic (三叠纪) /Jurassic American ones contained lakes, and these lakes grew and shrank at regular intervals because of climatic changes caused by periodic shifts in the earth’s orbit. (A similar phenomenon is responsible for modern ice ages.) That regularity, combined with reversals in the earth’s magnetic field, which are detectable in the tiny fields of certain magnetic minerals, means that rocks from this place and period can be dated to within a few thousand years. As a bonus, squishy (adj.粘糊糊的) lake-edge sediments are just the things for recording the tracks of passing animals. By dividing the labour between themselves, the ten authors of the paper were able to study such tracks at 80 sites.

E. The researchers looked at 18 so-called ichnotaxonomy(群落). These are recognizable types of footprint that cannot be matched precisely with the species of animal that left them. But they can be matched with a general sort of animal, and thus act as an indicator of the fate of that group, even when there are no bones to tell the story.

F. Five of the ichnotaxa disappear before the end of the Triassic, and four march confidently across the boundary into the Jurassic. Six, however, vanish at the boundary, or only just splutter across it; and three appear from nowhere, almost as soon as the Jurassic begins.

G. That boundary itself is suggestive. The first geological indication of the impact that killed the dinosaurs was an unusually high level of iridium in rocks at the end of the Cretaceous, when the beasts disappear from the fossil record. Iridium is normally rare at the earth’s surface, but it is more abundant in meteorites. When people began to believe the impact theory, they started looking  for  other  Cretaceous-end  anomalies.  One  that  turned  up  was  a surprising abundance of fern spores in rocks Just above the boundary layer-a phenomenon known as a “fern spike”(蕨类）

H. That matched the theory nicely. Many modern ferns are opportunists. They cannot compete against plants with leaves, but if a piece of land is cleared by, say, a volcanic eruption, they are often the first things to set up shop there. An asteroid strike would have scoured much of the earth of its vegetable cover, and provided a paradise for ferns. A fern spike in the rocks is thus a good indication that something terrible has happened.

I. Both an iridium (铱) anomaly and a fern spike appear in rocks at the end of the Triassic, too. That accounts for the disappearing ichnotaxa: the creatures that made them did not survive the holocaust. The surprise is how rapidly the new ichnotaxa appear. Eubrontes giganteus, for example, is there a mere 10,000 years after the iridium anomaly. The Eubrontes (一种大脚印）prints were made by theropods-the dinosaur group that went on to produce such nightmares as Allosaurus(异龙)and Tyrannosaurus(暴龙) -and Eubrontes is already 20% bigger than any theropod track recorded from the Triassic.

J. Dr Olsen and His colleagues suggest that the explanation for this rapid increase in size may be a phenomenon called ecological release. This is seen today when reptiles (which, in modern times, tend to be small creatures) reach islands where they face no competitors. The most spectacular example is on the Indonesian island of Komodo, where local lizards have grown so large that they are often referred to as dragons. The dinosaurs, in other words, could flourish only when the competition had been knocked out.

K. That leaves the question of where the impact happened. No large hole in the earth’s crust seems to be 202m years old. It may, of course, have been overlooked. Old craters are eroded and buried, and not always easy to find. Alternatively, it may have vanished. Although continental crust is more or less permanent, the ocean floor is constantly recycled by the tectonic processes that bring about continental drift. There is no ocean floor left that is more than 200m years old, soa crater that formed in the ocean would have been swallowed up by now.

L. There is a third possibility, however. This is that the crater is known, but has been misdated. The Manicouagan “structure”, a center in Quebec, is thought to be 214m years old. It is huge-some 100km across-and seems to be the largest of between three and five craters that formed within a few hours of each other as the lumps of a disintegrated comet hit the earth one by one. Such an impact would surely have had a perceptible effect on the world, but the rocks from 214m years ago do not record one. It is possible, therefore, that Manicouagan (根陨石坑) has been misdated. That will be the next thing to check.

 

Question 1-6

Do the following statements agree with the information given in Reading Passage 1?

In boxes1-6 on your answer sheet, write

TRUE if the statement agrees with the information

FALSE if the statement contradicts the information

NOT GIVEN if there is no information on this

 

1.Dr Paul Olsen and his colleagues believe that asteroid knock may also lead to dinosaurs ‘boom

2. Books and movie like Jurassic Park often exaggerate the size of the dinosaurs.

3 Dinosaur footprints are more adequate than dinosaur skeletons.

4 The prints were chosen by Dr Olsen to study because they are convenient to tracked down into a date of geological precise within thousands of years.

5 Ichnotaxa showed that footprints of dinosaurs offer exact information of the trace left by an individual species.

6 We can find more Iridium in the earth’s surface than in meteorites.

 

Questions 7-13

Complete the following summary of the paragraphs of Reading Passage, using no more than two words from the Reading Passage for each answer. Write your answers in

boxes 7-13 0n your answer sheet.

Dr Olsen and his colleagues applied a phenomenon named 7_____ to explain the large size of the Eubrontes, which is a similar case to that nowadays reptiles invade a place where there are no 8 _____ ; for example, on an island called Komodo, indigenous huge lizards grow so big that people even referring them as 9 _____. However, there were no old impact trace being found? The answer may be that we have 10 _____ the evidence. Old craters are difficult to spot or it probably 11 ______ due to the effect of the earth moving. Even a crater formed in Ocean had been 12 _____ under the impact of crust movement. Beside, the third hypothesis is that the potential evidences- some craters may be 13 ______.

 

P2 Food for Thought 非洲饥荒问题 （文章是2017.6.24旧文重现，但是题目只有Heading题相同）

文章主旨: 介绍非洲地区的饥荒问题

包含Heading题7题，判断题3题，选择题3题。

参考答案:

Heading题 14-20

14. vi

15. iv.

16. viii

17. ii.

18. viii.

19. iii.

20. vii.

判断题 21-23

答案待补充

选择题 24-26

答案待补充

 

P3 Group Behavior 合作行为

文章主旨: 科学家对于团队合作的研究

包含人名观点配对题和填空题

参考答案:

待补充

 

考试预测

1. 本场考试难度为中等偏上，文章选材涉及科学、环境和社会类，考生可在备考时关注相应高频主题词。

2. 此次考试中，难度较低的两篇文章都是旧题。因此，考生在刷题时，除了做剑桥雅思题，也应多关注机经。

3. 从题型组合方面来看，相对简单的P1为判断和填空的顺序题组合，考生应保证又快又好地做完。P2是的难度也不高，是Heading题和判断选择题的组合，应先做顺序的判断和选择题，再做乱序的Heading题。P3虽然较难，但是考察的人名观点配对题和填空题都不是很难做。应对这样的题型组合，考生需要准确高效地进行定位和同义替换。总的来说，考生在课余时间还是需要多做练习，方可巩固做题技巧。

4. 下场考试的话题可能有关人物传记和历史类话题。

5.重点浏览14-16年机经。

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