首页
登录
职称英语
Why don’t birds get lost on their long flights from one place to another? Sc
Why don’t birds get lost on their long flights from one place to another? Sc
游客
2023-10-08
55
管理
问题
Why don’t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for many years. Now they are beginning to fill in the blanks.
Not long ago, experiments showed that birds depend on the sun to guide them during day-flight hours. But what about birds that fly by night? Tests with man-made stars have proved that certain night-flying birds are able to follow the stars in their long-distance flights.
A dove spent its lifetime in a cage and had never flown under a natural sky. Yet it showed an inborn ability to use the stars for guidance. The bird’s cage was placed under a man-made star-filled sky. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the make-believe stars caused a change in the direction of his flight.
Scientists think that doves, flying ill daylight, use the sun for guidance. But the stars are obviously their most important means of navigation (or flying). What do they do when the stars are hidden by clouds? Obviously, they find their way by such landmarks as mountains ranges, coastlines, and river courses. But when it is too dark to see these, the doves circle helplessly, unable to get their bearings.
选项
A、has been discovered recently
B、is known by everybody
C、still remains a mystery
D、has been known to scientists for years
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3082303.html
相关试题推荐
65.Qantas(广达斯航空公司)hasmoreflightstomoreplacesthananyotherAustralianair
Allflightshavebeencancelledbecauseofthesnowstorm,somanypassengerscoul
[originaltext]I’mgoingtotakeanotherpieceofcake.Wouldyoulikesome?[/o
Whydon’tbirdsgetlostontheirlongflightsfromoneplacetoanother?Sc
Whydon’tbirdsgetlostontheirlongflightsfromoneplacetoanother?Sc
Whydon’tbirdsgetlostontheirlongflightsfromoneplacetoanother?Sci
______areply,hedecidedtowriteanotherletter.A、NotreceivingB、Havingnot
Atonetimeoranotherwehaveallstoppedtothinkabouttheweather.Somed
[originaltext]M:Howlongisthetrip?W:It’s17hourstoParisandanother6
[originaltext]Wouldyoulikeanotherbeer,Mr.White?[/originaltext]A、I’mthirs
随机试题
TheLandofDisneyPredictingthefutureisalwaysris
Howeverimportantwemayregardschoollifetobe,thereisnodenyingthat
Thecompanyhadtoputforwarda(propose)______thatlay-offs(下岗)beconsidered.p
Thecarhasreshapedourcities.Itseemstoofferautonomyforeveryone.Th
[originaltext]M:Sheila,you’reoneofthespeakersfortheEnglishSpeakingCo
从明朝开始,小说作为一种文学形式全面展现出它的社会功能和文学价值。明朝和清朝早期的小说代表了中国古典小说的最高峰(pinnacle),实现了展示新的文化
国家"十五"攻关缺血性心血管疾病发病风险的评估是目前常用的健康风险评估方法之一,
国家电网公司变电运维管理规定变电站遇有()情况,应进行特殊巡视。大风后$;
闪电图是在图中按时间等分,将每分钟的最新价格标出的图示方法,它随着时间延续就会出
(2019年真题)某建设工程承包人在工程完工后于2月1日提交了竣工验收报告,发包
最新回复
(
0
)