首页
登录
职称英语
Bird wings have a much more complex job to do than wings of an airplane, for
Bird wings have a much more complex job to do than wings of an airplane, for
游客
2025-04-14
23
管理
问题
Bird wings have a much more complex job to do than 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 of a bird conforms to the same aerodynamic principles as those eventually discovered by people when designing airplanes, and if you know how different kind 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 Word War to make tight turns and acrobatic maneuvers in a dog-fight. More modem fighters achieve greater speeds by sweeping back their wings while in flight, just as peregrines do when they go into a 130 kph 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. [br] What’s the main idea of the passage?
选项
A、Bird wings are more complex than airplane wings.
B、People design airplane by looking at the wing shapes of birds.
C、How we can make the airplane wings more efficient.
D、The wings of birds and airplanes conform to the same aerodynamic principles.
答案
D
解析
根据文章第一段最后一句“Even so the wing outline of a bird conforms to the sameaerodynamic principles as those eventually discovered by people when designing airplanes,and ifyou know how different kind of aircraft perform,you can predict the flight capabilities of similarlyshaped birds.”可知,即便如此,鸟类翅膀的轮廓与人们最终发现并应用于飞机设计的空气动力学原理是吻合的。如果你了解不同飞机的飞行性能,你就能够判断出具有同样形状翅膀的鸟儿的飞行能力。这一句起到总领全文的作用。据此判断,本题选D。
转载请注明原文地址:https://tihaiku.com/zcyy/4037741.html
相关试题推荐
Plantadaptationcanberemarkablycomplex.Certainspeciesoforchids,fori
Terroristsmurderandkidnappeople,______bombs,hijackairplanes,setfires,
Birdwingshaveamuchmorecomplexjobtodothanwingsofanairplane,for
Birdwingshaveamuchmorecomplexjobtodothanwingsofanairplane,for
Birdwingshaveamuchmorecomplexjobtodothanthewingsofanairplane,
Birdwingshaveamuchmorecomplexjobtodothanthewingsofanairplane,
Birdwingshaveamuchmorecomplexjobtodothanthewingsofanairplane,
Permissiontobuildthefactoryhasbeendelayedbythecomplex_____betweenindu
Insuchachanging,complexsocietyformerlysimplesolutionstoinformation
Insuchachanging,complexsocietyformerlysimplesolutionstoinformation
随机试题
OneofthebestAknownandlavishlyBpraisingarchitecturalprojectsofthetwen
Aswellastheproblemsconcernedwithobtaininggoodqualityaudiorecording
Whatcanweknowabouttheintervieweefromtheinterview?[br][originaltext]W
Ascientistwhowantstopredictthewayinwhichconsumerswillspendthei
Wehavechosenwhatwebelievetobethefivemostspectacularnaturalwonde
胆固醇是临床生化检查的一个重要指标,在正常情况下,人体胆固醇合成的主要场所是(
以下个年中,国有建设用地供应面积同比增量最多的年份是:A.2010 B.2
只对肠外阿米巴有效的药物是A.氯喹B.依米丁C.喹碘方D.甲硝唑E.巴龙霉素
乳剂型气雾剂为A.二相气雾剂 B.三相气雾剂 C.双相气雾剂 D.吸入粉雾
某独立柱基的基底尺寸为2600mm×5200mm,柱底由荷载标准值组合所得的内力
最新回复
(
0
)