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
2015-01-09
49
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 speedsby 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/tdQO777K
0
考博英语
相关试题推荐
PeopleplanningtotravelbycartoNorthDakotainthewinterareadvisedto______theircarswithsnowtiresandwarmclothing
Couplesblessedwithstrengthandaggression______looksarebetteroffhavingboys,asthesecharacteristicsareofmoreuseto
Writersnowadayswhovaluetheirreputationamongthemoresophisticatedhardlydaretomentionprogresswithoutincludingthew
Whetherapolicythatis"good"intheaggregatesense______also"good"foraparticularperson,however,______adifferentmatt
AnOhioStateUniversitystudyhaslinkedbehaviorinyoungchildren【1】thetypeofjobtheirmotherhas.Motherswithcomplexoc
Cultureisactivityofthought,andreceptivenesstobeautyandhumanefeeling.【1】ofinformationhavenothingtodowithit.Am
Alisonclosedthedoorofhersmallflatandputdownherbriefcase.Asusual,shehadbroughtsomeworkhomefromthetravelag
Alittlemorethanacenturyago,MichaelFaraday,anotedBritishphysicist,managedtogainaudiencewithagroupofhighgove
Youaresupposedtowritealetterofthanks,expressingyourthankstotheorganizingcommitteeforthe$3,000ithasoffered
随机试题
三疣梭子蟹以南海所产最为著名。()
鉴定真菌最常用的简便方法是A.革兰染色后镜检B.动物接种C.血清学鉴定D.皮肤变态反应E.直接镜检形态结构
某建筑柱下桩基为三桩承台基础,现场竖向抗拔载荷试验,测得三根试桩的单桩竖向抗拔极限承载力分别为:530kN、560kN、580kN,则其单桩竖向抗拔承载力特征值(kN)应为下列()项。
根据现行营改增政策,下列说法正确的是()。
在定时截尾的可靠性鉴定试验中,与试验方案无关的参数有()。
奥苏伯尔根据学习进行的方式把学习分为接受学习与发现学习;根据学习材料与学习者原有知识结构的关系把学习分为机械学习与意义学习,他强调的是______学习。
甲公司在民政部门主办的大型赈灾义演会上,当众宣布向民政部门设立的救灾基金捐赠100万元。事后,甲公司迟迟未支付捐款。以下说法哪一项是正确的?()
a、b、c都是质数,如果(a+b)×(b+c)=342,那么b=?
CyclinginLondonislesspleasantthaninmanyEuropeancities.Mainroadsteemwithlorries;windingbackstreetsarehardto
【B1】【B3】
最新回复
(
0
)