A
Birdshave many unique design features that enable them to perform such amazing featsof endurance. 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
Thefundamental reason that birds migrate is to find adequate food during thewinter months when it is in short supply. This particularly applies to birdsthat breed in the temperate and Arctic regions of the Northern Hemisphere,where food is abundant during the short growing season. Many species cantolerate cold temperatures if food is plentiful, but when food is not availablethey must migrate. However, intriguing questions remain.
C
Onepuzzling fact is that many birds journey much further than would be necessaryjust to find food and good weather. Nobody knows, for instance, why Britishswallows, which could presumably survive equally well if they spent the winterin equatorial Africa, instead fly several thousands of miles further to theirpreferred winter home in South Africa Cape Province. Another mystery involvesthe huge migrations performed by arctic terns and mud flat-feeding shorebirdsthat breed close to Polar Regions. In general, the further north a migrantspecies breeds, the farther south it spends the winter. For arctic terns thisnecessitates an annual round trip of 25,000 miles. Yet, en route to their finaldestination in far-flung southern latitudes, all these individuals overflyother areas of seemingly suitable habitat spanning two hemispheres. While wemay not fully understand birds' reasons for going to particular places, we canmarvel at their feats.
D
One ofthe greatest mysteries is how young birds know how to find the traditionalwintering areas without parental guidance. Very few adults migrate withjuveniles in tow, and youngsters may even have little or no inkling of theirparents' appearance. A familiar example is that of the cuckoo, which lays itseggs in another species nest and never encounters its young again. It is mindboggling to consider that, once raised by its host species, the young cuckoomakes its own way to ancestral wintering grounds in the tropics beforereturning single-handed to northern Europe the next season to seek out a mateamong its own kind. The obvious implication is that it inherits from itsparents an inbuilt route map and direction-finding capability, as well as a mentalimage of what another cuckoo looks like. Yet nobody has the slightest idea asto how this is possible.
E
Mountingevidence has confirmed that birds use the positions of the sun and stars toobtain compass directions. They seem also to be able to detect the earth'smagnetic field, probably due to having minute crystals of magnetite in theregion of their brains. However, true navigation also requires an awareness ofposition and time, especially when lost. Experiments have shown that afterbeing taken thousands of miles over an unfamiliar landmass, birds are stillcapable of returning rapidly to nest sites. Such phenomenal powers arc theproduct of computing a number of sophisticated cues, including an inborn map ofthe night sky and the pull of the earth's magnetic field. How the birds usetheir 'instruments’ remains unknown, but one thing is clear: they see the worldwith a superior sensory perception to ours. Most small birds migrate at nightand take their direction from the position of the setting sun. However, as wellas seeing 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,all journeys involve considerable risk, and part of the skill in arrivingsafely is setting off at the right time. This means accurate weatherforecasting, and utilizing favorable winds. Birds are adept at both, and, inlaboratory tests, some have been shown to detect the minute difference inbarometric pressure between the floor and ceiling of a room. Often birds reactto weather changes before there is any visible sign of them. Lapwings, whichfeed on grassland, flee west from the Netherlands to the British Isles, Franceand Spain at the onset of a cold snap. When the ground surface freezes thebirds could starve. Yet they return to Holland ahead of a thaw, their arrivallinked to a pressure change presaging an improvement in the weather.
G
In oneinstance a Welsh Manx shearwater carried to America and released was back inits burrow on Skokholm Island, off the Pembrokeshire coast, one clay before aletter announcing 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.
Questions14-20
Readingpassage 2 has seven paragraphs, A-G
Choosethe correct heading for each paragraph from the list of headings below. Write
thecorrect number, i-x, in boxes 14-20 on your answer sheet.
List ofheadings
i. Thebest moment to migrate
ii. Theunexplained rejection of closer feeding ground
iii. Theinfluence of weather on the migration route
iv.Physical characteristics that allow birds to migrate
v. Themain reason why birds migrate
vi. Thebest wintering grounds for birds
vii.Research findings on how birds migrate
viii.Successful migration despite trouble of wind
ix.Contrast between long-distance migration and short-distance migration
x.Mysterious migration despite lack of teaching
14Paragraph A
15Paragraph B
16Paragraph C
17Paragraph D
18Paragraph E
19 ParagraphF
20Paragraph G
Questions21-22
ChooseTWO letters, A-E.
Writethe correct letters in boxes 21 and 22 on your answer sheet.
WhichTWO of the following statements are true of bird migration?
A Birdsoften fly further than they need to.
B Birdstraveling in family groups are safe.
C Birdsflying at night need less water.
D Birdshave much sharper eye-sight than humans.
E Onlyshorebirds are resistant to strong winds.
Questions23-26
Completethe sentences below using NO MORE THAN TWO WORDS from the
passage.
Writeyour answers in boxes 23-26 on your answer sheet.
23 It isa great mystery that young birds like cuckoos can find their wintering groundswithout ________.
24Evidence shows birds can tell directions like a ________by observing the sunand the stars.
25 Oneadvantage for birds flying at night is that they can avoid contact with ______.
26Laboratory tests show that birds can detect weather without ________signs.
试题分析答案：
Question14-20
题目类型：List of headings
Question21-22
题目类型：details of paragraphs
Question23-26
题目类型：Passage filling
题号定位词文中对应点题目解析
14Design features that enable them to perform such amazing feats A段第一句A段开门见山提出鸟类特有的结构特征支持它们迁徙。之后就细化介绍了它们的特殊结构。
是个典型总分结构。所以第一句就是主题句，
因此，本题答案为iv。
15Fundamental reason that birds migrate B段第一句B段开始提出了本段主题，之后给出了迁徙原因的解释。
因此，本题答案为 v。
16Puzzling fact; much further C段第一句C段也是直接提出主题，然后用例子进行解释的结构。C段提出了鸟类飞到更远的地方过冬令人不解，接着用英国的燕子和北极燕鸥和水禽的迁徙例子来具体说明了人们的惊讶。
Puzzling对应答案中的unexplained;much further对应答案中rejection of closer
因此，本题答案为 ii。
17Greatest mysteries; how young birds D段第一句D段第一句是主题句，整段接着用杜鹃的例子来具体化了此疑问。
Youngbird体现了答案中的lack of teaching
因此，本题答案为 x。
18Mounting evidence; birds use the positions; to obtain compass direction; detectthe earth’s magnetic field E段第一句第二句E段第一句提出了鸟类使用太阳和星星辨别方向有很多证据。第二句说同时鸟类似乎还可以预测地球磁场。这都在说鸟儿怎么飞。
因此，本题答案为 vii。
19Setting off at the right time F段第一句F段第一句话提出安全飞行需要找到最好的出发的时间，第二句说那意味着要正确的天气预测，利用风向。也就是说第二句只是说明如何找到好的出发时间，说要iii 不能选。
因此，本题答案为 I。
20 Oneinstance; are blown across; fast-moving westerly tail winds; arrive safely G段第一句和第二句和第三句。G段第一句说威尔士马恩岛海鸥是一个例子(那说明是承接上文的例子，而上面一段说的是正确预测天气和利用风向来找到好的飞行时间)。所以这要么是预测天气成功，要么是利用风向成功。后面第二句说到了西尾风。第三句说不仅成功，还飞去了非洲。
因此，本题答案为 viii。
21 Manybirds journey much further than would be necessary just to find food C段第一句C段第一句明确提到许多鸟类的迁徙旅程远远长于它们为了寻找食物和好天气所必需飞行的距离。这也是C段的主题句。
因此，本题答案为 A。
22Traveling at night; other benefits; danger of dehydration E段第九十两句E段接近结尾的第九十两句非常明确的提到了夜间飞行的好处：避免天敌和脱水。
因此，本题答案为C。
其它选项B在文中没有提到和家人一起飞行;D也没有提到，文章只是在第E段提到的是鸟类有比人类更高级的感官知觉they see the world with asuperior sensory perception to ours。E也没有在文中明确提出，并且一般有绝对词的答案可以率先排除。
23 Oneof the greatest mysteries; without parental guidance; a familiar example isthat of the cuckoo D段第一句话和第三句话先用cuckoo定位到D段。
Cuckoo是该段主题幼鸟依靠自己迁徙到越冬之地的迷思的一个例子。
提干部分是对D段第一句话的paraphrase。
因此，本题答案是文中的parental guidance。
24Mounting evidence; position of sun and stars to obtain compass directions E段第一句话用tell direction和by observing the sun and thestars定位到E段第一句话。
因此，本题答案是文中的compass。
25Traveling at night; other benefits; daytime predators are avoided E段第九十两句通过第22题其实已经可以直接做出这个题了。E段接近结尾的第九十两句非常明确的提到了夜间飞行的好处：避免天敌和脱水。
因此，本题答案为predators。
26 Reactto weather changes before there is any visible sign of them F段第四句用laboratory tests; detect weather定位到本句。
因此，本题答案为visible。
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