阅读
Passage 1主题：恐龙脚印（The Dinosaurs Footprints andExtinction）
原文：
A
EVERYBODY knows that the dinosaurs were killed by an asteroid. Somethingbig hit the earth 65 million years ago and, when the dust had fallen, so hadthe great reptiles. There is thus a nice if ironic, symmetry in the idea that asimilar impact brought about the dinosaurs’ rise. That is the thesis proposedby Paul Olsen, of Columbia University, and his colleagues in this week’sScience.
B
Dinosaurs first appeared in the fossil record 230m years ago, during theTriassic period. But they were mostly small, and they shared the earth withlots of other sorts of reptile. It was in the subsequent Jurassic, which began202 million years ago, that they overran the planet and turned into themonsters depicted in the book and movie “Jurassic Park”. (Actually, though, thedinosaurs that appeared on screen were from the still more recent Cretaceousperiod.) Dr Olsen and his colleagues are not the first to suggest that thedinosaurs inherited the earth as the result of an asteroid strike. But they arethe first to show that the takeover did, indeed, happen in a geologicaleyeblink.
C
Dinosaur skeletons are rare. Dinosaur footprints are, however, surprisinglyabundant. And the sizes of the prints are as good an indication of the sizes ofthe 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 theworld the full of rift valleys to those in East Africa today. Like the modernAfrican rift valleys, the Triassic/Jurassic American ones contained lakes, andthese lakes grew and shrank at regular intervals because of climatic changescaused by periodic shifts in the earth’s orbit. (A similar phenomenon isresponsible for modern ice ages.) That regularity, combined with reversals inthe earth’s magnetic field, which are detectable in the tiny fields of certainmagnetic minerals, means that rocks from this place and period can be dated towithin a few thousand years. As a bonus, squishy lake-edge sediments are justthe things for recording the tracks of passing animals. By dividing the labourbetween themselves, the ten authors of the paper were able to study such tracksat 80 sites.
E
The researchers looked at 18 so-called ichnotaxa. These are recognizabletypes of the footprint that cannot be matched precisely with the species ofanimal 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 nobones to tell the story. Five of the ichnotaxa disappear before the end of theTriassic, and four march confidently across the boundary into the Jurassic.Six, however, vanish at the boundary, or only just splutter across it; andthere appear from nowhere, almost as soon as the Jurassic begins.
F
That boundary itself is suggestive. The first geological indication of theimpact that killed the dinosaurs was an unusually high level of iridium inrocks at the end of the Cretaceous when the beasts disappear from the fossilrecord. Iridium is normally rare at the earth’s surface, but it is moreabundant in meteorites. When people began to believe the impact theory, theystarted looking for other Cretaceous-and anomalies. One that turned up was asurprising abundance of fern spores in rocks just above the boundary layer – aphenomenon known as a “fern spike”.
G
That matched the theory nicely. Many modern ferns are opportunists. Theycannot compete against plants with leaves, but if a piece of land is clearedby, say, a volcanic eruption, they are often the first things to set up shopthere. An asteroid strike would have scoured much of the earth of its vegetablecover, and provided a paradise for ferns. A fern spike in the rocks is thus agood indication that something terrible has happened.
H
Both an iridium anomaly and a fern spike appear in rocks at the end of theTriassic, too. That accounts for the disappearing ichnotaxa: the creatures thatmade them did not survive the holocaust. The surprise is how rapidly the newichnotaxa appear.
I
Dr Olsen and his colleagues suggest that the explanation for this rapidincrease in size may be a phenomenon called ecological release. This is seentoday when reptiles (which, in modern times, tend to be small creatures) reachislands where they face no competitors. The most spectacular example is on theIndonesian island of Komodo, where local lizards have grown so large that theyare often referred to as dragons. The dinosaurs, in other words, could flourishonly when the competition had been knocked out.
J
That leaves the question of where the impact happened. No large hole in theearth’s crust seems to be 202m years old. It may, of course, have beenoverlooked. Old craters are eroded and buried, and not always easy to find.Alternatively, it may have vanished. Although the continental crust is more orless permanent, the ocean floor is constantly recycled by the tectonicprocesses that bring about continental drift. There is no ocean floor left thatis more than 200m years old, so a crater that formed in the ocean would havebeen swallowed up by now.
K
There is a third possibility, however. This is that the crater is known,but has been misdated. The Manicouagan “structure”, a crater in Quebec, isthought to be 214m years old. It is huge – some 100km across – and seems to bethe largest of between three and five craters that formed within a few hours ofeach other as the lumps of a disintegrated comet hit the earth one by one.
Questions 1 – 6
Do the following statements agree with the information given in ReadingPassage 1?
In boxes 1–6 on your answer sheet, write
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if the information is not given in the passage
1 Paul Olsen and his colleagues believe that asteroid strikes may also leadto a dinosaur species boom.
2 The books and movies like Jurassic Park often exaggerate the size of thedinosaurs.
3 Dinosaur footprints are more abundant than dinosaur skeletons.
4 Footprints were chosen by Dr. Olsen to study because they are moredetect-able than the Earth’s magnetic field
to track the date with precision over thousands of years.
5 The Ichnotaxa indicated that dinosaur footprints provide accurate informationabout the tracks left by a
particular species.
6 We can find more iridium on the Earth’s surface than in meteorites.
Questions 7 – 13
Complete the summary below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 7–13 on your answer sheet.
Dr. Olsen and his team have tried to use the so-called 7_____ to explainwhy the Eubrontes is so large, which is similar to what happens when smallreptiles invade places in which there is no 8_____. On an island in Indonesia,for example, lizards ten to be big than normal, so the inhabitants there willregard them as 9_____.
But why have no traces of the old impact been found? The answer may be thatwe have 10_____ the evidence because old craters are difficult to spot. Or, thecrater left probably 11_____. Even a crater formed in the ocean is likely tohave been 12_____ by crustal movements. In addition, a third hypothesis raisespotential evidence that the crater might be 13_____.
Answer keys
1. True
2. Not Given
3. True
4. Not given
5. False
6. False
7. ecological release
8. competitors
9. dragons
10. overlooked
11. (have) vanished
12 .swallowed up
13. misdated
Passage 2 主题：电影制作
Passage 3 主题：教听障孩子手语/唇语(sign language)
听力
P1：电影俱乐部
1. There movies : Comedy, Romantic and the third one is actionfilm/movie.Inclub, except for movie,
There is: 2. discussion (for thrillers惊悚片)
3. 俱乐部除了电影还有什么活动afteractivity:exhibition(foraction movie动作片)
4. The 3rd movie screen room can hold up to: 450 people the first twotheatres are both 150,but the third is 450.
5. 2nd movie starting date: 17th April it was planned on 10th, then postpone7 to date of~
6. is there is any meeting held, the movie will not be displayed.
7. Membership fee is to be paid every month not week
8. in bookshop , you will have a discount if hold membership card.
9. will send: tickets for Special program to you for free (plural, becausethere is lots of events)
10. Gold Member: You can take (bring)a guest for free.还可以免费带1人
P2：城市道路改善
P3：学校课程讨论
P4：虫子
31.They have a lot of protein and contain vitamins
32.Their waste products don't harm the soil or the rivers onfarmland.
33.Their production requires less expense and little space
34.Some can be added to animal feed as a kind of antibiotic
35.people may be harmed by the bacteria they contain.
36.it can supply the growing demandin the cities of some countries
37. the taste of the insects may be affecteo
38.Farmers and researchers are unclear how to deal with disease
39.Better tanks need to be developed so cleaning is faster
40.Farmers need to develop a strategy for marketing the insects.
|Archiver|手机版|小黑屋|雅思托福英语全球网
( 闽ICP备14014910号 )
|
闽公网安备 35020302034732号
发表于 2024-10-24 08:33:55
QQ好友和群
QQ空间
腾讯微博
腾讯朋友
收藏