原文：
A
Birds have manyunique design features that enable them to perform such amazing feats ofendurance. They are equipped with lightweight, hollow bones, intricatelydesigned feathers providing both lift and thrust for rapid flight, navigationsystems superior to any that man has developed, and an ingenious heatconserving design that, among other things, concentrates all blood circulationbeneath layers of warm, waterproof plumage, leaving them fit to face life inthe harshest of climates. Their respiratory systems have to perform efficientlyduring sustained flights at altitude, so they have a system of extractingoxygen from their lungs that far exceeds that of any other animal. During thelater stages of the summer breeding season, when food is plentiful their bodiesare able to accumulate considerable layers of fat, in order to providesufficient energy for their long migratory flights.
B
The fundamentalreason that birds migrate is to find adequate food during the winter monthswhen it is in short supply. This particularly applies to birds that breed inthe temperate and Arctic regions of the Northern Hemisphere, where food isabundant during the short growing season. Many species can tolerate coldtemperatures if food is plentiful, but when food is not available they mustmigrate. However, intriguing questions remain.
C
One puzzling factis that many birds journey much further than would be necessary just to findfood and good weather. Nobody knows, for instance, why British swallows, whichcould presumably survive equally well if they spent the winter in equatorialAfrica, instead fly several thousands of miles further to their preferredwinter home in South Africa Cape Province. Another mystery involves the hugemigrations performed by arctic terns and mud flat-feeding shorebirds that breedclose to Polar Regions. In general, the further north a migrant species breeds,the farther south it spends the winter. For arctic terns this necessitates anannual round trip of 25,000 miles. Yet, en route to their final destination infar-flung southern latitudes, all these individuals overfly other areas ofseemingly suitable habitat spanning two hemispheres. While we may not fullyunderstand birds' reasons for going to particular places, we can marvel attheir feats.
D
One of the greatestmysteries is how young birds know how to find the traditional wintering areaswithout parental guidance. Very few adults migrate with juveniles in tow, andyoungsters may even have little or no inkling of their parents' appearance. A familiarexample is that of the cuckoo, which lays its eggs in another species nest andnever encounters its young again. It is mind boggling to consider that, onceraised by its host species, the young cuckoo makes its own way to ancestralwintering grounds in the tropics before returning single-handed to northernEurope the next season to seek out a mate among its own kind. The obviousimplication is that it inherits from its parents an inbuilt route map anddirection-finding capability, as well as a mental image of what another cuckoolooks like. Yet nobody has the slightest idea as to how this is possible.
E
Mounting evidencehas confirmed that birds use the positions of the sun and stars to obtaincompass directions. They seem also to be able to detect the earth's magneticfield, probably due to having minute crystals of magnetite in the region oftheir brains. However, true navigation also requires an awareness of positionand time, especially when lost. Experiments have shown that after being takenthousands of miles over an unfamiliar landmass, birds are still capable ofreturning rapidly to nest sites. Such phenomenal powers arc the product ofcomputing a number of sophisticated cues, including an inborn map of the nightsky and the pull of the earth's magnetic field. How the birds use their'instruments’ remains unknown, but one thing is clear: they see the world witha superior sensory perception to ours. Most small birds migrate at night andtake their direction from the position of the setting sun. However, as well asseeing the sun go down, they also seem to sec the plane of polarized lightcaused by it, which calibrates their compass. Traveling at night provides otherbenefits. Daytime predators are avoided and the danger of dehydration due to flyingfor long periods in warm, sunlit skies is reduced. Furthermore, at night theair is generally cool and less turbulent and so conducive to sustained, stableflight.
F
Nevertheless, alljourneys involve considerable risk, and part of the skill in arriving safely issetting off at the right time. This means accurate weather forecasting, andutilizing favorable winds. Birds are adept at both, and, in laboratory tests,some have been shown to detect the minute difference in barometric pressurebetween the floor and ceiling of a room. Often birds react to weather changesbefore there is any visible sign of them. Lapwings, which feed on grassland,flee west from the Netherlands to the British Isles, France and Spain at theonset of a cold snap. When the ground surface freezes the birds could starve.Yet they return to Holland ahead of a thaw, their arrival linked to a pressurechange presaging an improvement in the weather.
G
In one instance aWelsh Manx shearwater carried to America and released was back in its burrow onSkokholm Island, off the Pembrokeshire coast, one clay before a letterannouncing its release! Conversely, each autumn a small number of NorthAmerican birds arc blown across the Atlantic by fast-moving westerly tailwinds. Not only do they arrive safely in Europe, but, based on ringingevidence, some make it back to North America the following spring, afterprobably spending the winter with European migrants in sunny African climes.
Questions 14-20
Reading passage 2has seven paragraphs, A-G
Choose the correctheading for each paragraph from the list of headings below. Write
the correct number,i-x, in boxes 14-20 on your answer sheet.
List of headings
i. The best momentto migrate
ii. The unexplainedrejection of closer feeding ground
iii. The influenceof weather on the migration route
iv. Physicalcharacteristics that allow birds to migrate
v. The main reasonwhy birds migrate
vi. The bestwintering grounds for birds
vii. Researchfindings on how birds migrate
viii. Successfulmigration despite trouble of wind
ix. Contrastbetween long-distance migration and short-distance migration
x. Mysteriousmigration despite lack of teaching
14 Paragraph A
15 Paragraph B
16 Paragraph C
17 Paragraph D
18 Paragraph E
19 Paragraph F
20 Paragraph G
Questions 21-22
Choose TWO letters,A-E.
Write the correctletters in boxes 21 and 22 on your answer sheet.
Which TWO of thefollowing statements are true of bird migration?
A Birds often flyfurther than they need to.
B Birds travelingin family groups are safe.
C Birds flying atnight need less water.
D Birds have muchsharper eye-sight than humans.
E Only shorebirdsare resistant to strong winds.
Questions 23-26
Complete thesentences below using NO MORE THAN TWO WORDS from the
passage.
Write your answersin boxes 23-26 on your answer sheet.
23 It is a greatmystery that young birds like cuckoos can find their wintering grounds without________.
24 Evidence showsbirds can tell directions like a ________by observing the sun and the stars.
25 One advantagefor birds flying at night is that they can avoid contact with ______.
26 Laboratory testsshow that birds can detect weather without ________signs.
答案解析：
14-20 matching
14. iv
【原文参考依据——A段首句】A段首句提到鸟类有许多独特的结构特征，使得它们表现出令人惊叹的耐力。之后论述了这些特征，换言之，讲的就是鸟类生理和解剖结构的特点如何适用飞行。
15. v
【原文参考依据——B段首句】The fundamental reason that birds migrate isto find adequate food during…….迁徙的基本目的是为了食物。
16. ii
【原文参考依据——C段首句】One puzzling fact is that many birds journeymuch further than would be necessary just to find food and good weather. 鸟类的旅程距离远远长于它们寻找食物和好天气所必须飞行的距离，说的就是"rejection of closer feedingground"，"puzzling"和"unplained"是同义表达。
17. x
【原文参考依据——D段首句】One of the greatest mysteries is how youngbirds know how to find the traditional wintering areas without parentalguidance. 鸟类不需要 parent guidence，"without"和"lackof"是同义表达。
18. vii
【原文参考依据——E段首句】Mouting evidence has confirmed that birdsuse the positions of the sun and stars to obtain compass directions. 大量的证据显示鸟类能够利用太阳和星星的方向来辨别方向，后面又例举了一些研究发现，说的正是对鸟如何迁徙的研究。
19. i
【原文参考依据——F段首句】Neverheless, all journeys involveconsiderable risk, and part of the skill in arriving safely is setting off atthe right time. “set off"与"migrate"是同义表达，the right time = the best moment。
20. viii
【原文参考依据——G段】整段讲的都是不管风带来的麻烦，鸟类都能成功迁徙。
21-22 选择题(in anyorder)
21、 A
【原文参考依据——C段首句】 ......journey much further than ......necessary
22、 C
【原文参考依据——E段倒数第二句】E段的倒数第二句说，鸟类在温暖日照下长时间飞行会有脱水危险，danger of dehydration (脱水，缺水)，反过来的意思就是鸟类夜间飞行所需要的水比较少。
23-26填空题
23、 parentalguidance
【原文参考依据——D段第一句话】根据"cuckoos"定位到D段。One of thegreatest mysteries is how young birds know how to find the traditionalwintering areas without parental guidance.
24、 compass
【原文参考依据——E段第一句话】根据"observing the sun and the stars"定位到E段第一句话。Moutingevidence has confirmed that birds use the positions of the sun and stars toobtain compass directions.
25、 predators
【原文参考依据——E段倒数第三行】E段倒数第四行提到，夜间飞行可以带来其他的好处——Daytime predators are avoided(倒三行)。
26、 visible
【原文参考依据——F段第七行】Birds are adept at both, in laboratorytests, some have been shown to detect the minute difference in barometricpressure between the floor and ceiling of a room. Often birds react to weatherchages before there is any visible sign of them.
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