首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Bird wings have a much more complex job to do than the wings of an airplane, for in addition to supporting the bird they must ac
Bird wings have a much more complex job to do than the wings of an airplane, for in addition to supporting the bird they must ac
admin
2012-07-18
22
问题
Bird wings have a much more complex job to do than the wings of an airplane, for in addition to supporting the bird they must act as its engine, rowing it through the air. Even so the wing outline or a bird conforms to the same aerodynamic principles as those eventually discovered by people when designing airplanes, and if you know how different kinds of aircraft perform, you can predict the flight capabilities of similarly shaped birds.
Short, stubby wings enable a tanager and other forest-living to swerve and dodge at speed through the undergrowth, just as they helped the fighter planes of the Second World War to make tight turns and acrobatic maneuvers in a dog-fight. More modern fighters achieve greater speeds by sweeping back their wings while in flight, just as peregrines do when they go into a 130kph dive, swooping to a kill. Championship gliders have long, thin wings so that, having gained height in a thermal up-current they can soar gently down for hours and an albatross, the largest of flying birds, with a similar wing shape and a span of 3 meters, can patrol the ocean for hours in the same way without a single wing beat. Vultures and hawks circle at very slow speeds supported by a thermal and they have the broad rectangular wings that very slow-flying aircraft have. People have not been able to adapt wings to provide hovering flight. That has only been achieved with the whirling, horizontal blades of a helicopter or the downward-pointing engines of a vertical landing jet. Hummingbirds have paralleled even this. They tilt their bodies so that they are almost upright and then beat their wings as fast as 80 times a second producing a similar downdraft of air. So the hummingbird can hover and even fly backwards.
Modern fighter planes can be compared to_____in the way they move.
选项
A、tanagers
B、hawks
C、peregrines
D、hummingbirds
答案
C
解析
题目问:现代战斗机的移动方式可以被比喻成什么?“More modern fighters achieve greater speeds by sweeping back their wings while in flight,just as peregrines do when they go into a 130kph dive,swooping to a kill.”通过这句话可知,现代战斗机在参加战斗时通过收拢机翼可以达到更大速度,就像鹰隼以130千米/时俯冲捕猎时的速度。据此判断,应选择C。
转载请注明原文地址:https://kaotiyun.com/show/m4nO777K
0
考博英语
相关试题推荐
______theFirstWorldWar,theUnitedStatesbecamethedominantforceinthemotion-pictureindustry.
AlthoughMs.Brownfoundsomeofherdutiestobe______,hersupervisionoffortyworkerswasaconsiderableresponsibility.
AttheKyotoconferenceonglobalwarminginDecember1997,itbecameabundantlyclearhowcomplexithasbecometoworkoutint
AttheKyotoconferenceonglobalwarminginDecember1997,itbecameabundantlyclearhowcomplexithasbecometoworkoutint
AttheKyotoconferenceonglobalwarminginDecember1997,itbecameabundantlyclearhowcomplexithasbecometoworkoutint
Everythingintoday’sworldisgoingfasterandfaster,andtelevisioncommercialsarenoexception.Atthestartofthetelevis
Floorsandwallsmustbespeciallyconstructedtomakeabuildingsoundproof.
OneofNike’sfounders,PhillipHampsonKnighthadbeenatopathletewhenhewasattheUniversityofOregonandhemovedonto
Whenwecreditthesuccessfulpeoplewithintelligence,physicalstrengthorgoodluck,wearemakingexcusesforourselvesbeca
TheDepartmentistheleadproviderofessential______,withresponsibilityfortransport,portsandmarine,freight,informatio
随机试题
ItwasJane______boughtadictionaryfromasecond-handbookstoreyesterday.
与紫外线所致DNA损伤修复有关的酶是
肺气不得宣散,上逆喉间,气道窒塞,呼吸急促,称为
隧洞开挖时,掏槽孔装药最多,周边孔装药较少,也就是掏槽孔药卷直径大些,连续装药,周边孔药卷直径小些,间隔装药,()在两者之间。
对于设计耐火极限大于1.50h的构件、全钢结构建筑,宜选用()。
蛙眼主“静”,这是一种极其冷峻的“静观”。宋代程颢《秋日偶成》曰:“万物静观皆自得,四时佳兴与人同。”“静”中观“动”也许更加敏锐,如同暗夜可观微弱荧光。“日理万机"固然可敬.闲庭踱步做些长远的战略思考也不可或缺。诸葛先生“草堂春睡足,窗外日迟迟”却独能大
PPP中的安全认证协议是(),它使用三次握手的会话过程传送密文。
Fromthehealthpointofviewwearelivinginamarvelousage.Weareimmunizedfrombirthagainstmanyofthemostdangerousd
A、Pickupthemail.B、Lookafterherdog.C、Waterplants.D、Takecareofgoldfish.A题干问“辛迪不在的时候,罗布有什么不用做的?”女士说,她已经取消了邮件,所以男士不用去帮
EducationisanenormousandexpensivepartofAmericanlife.Itssizeismatchedbyitsvariety.DifferencesinAmericansc
最新回复
(
0
)