首页
登录
职称英语
Why don’t birds get lost on their long migratory (迁徙) flight? Scientists have
Why don’t birds get lost on their long migratory (迁徙) flight? Scientists have
游客
2023-10-11
11
管理
问题
Why don’t birds get lost on their long migratory (迁徙) flight? 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 rely on the sun to guide them during day-light hours. But what about birds that fly mainly by night? Tests with artificial (人造的) stars have proved conclusively that certain night-flying birds are able to follow stars in their long-distance flights.
One such bird--a warbler--had spent its lifetime in a cage and had never flown under a natural sky. Yet it showed an inborn ability to use stars for guidance. The bird’s cage was placed under an artificial star-filled sky at migration time. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the artificial stars caused a change in the direction of his flight.
Scientists think that warblers, when flying in daylight, use the sun for guidance. But stars are apparently their main means of directed flight in the night. What do they do when stars are hidden by clouds? Apparently, they find their way by such landmarks as mountain ranges, coast lines and river courses. But when it is too dark to see these, the warblers circle helplessly, unable to find their way. [br] What do we know about the experimental warbler?
选项
A、It had never flown freely outdoors.
B、It was set free for the experiment.
C、It had never been placed under the sun.
D、It had lost its way in its daylight flight.
答案
A
解析
短文第三段主要介绍二项实验,第一句话就介绍用于实验的鸟类,即一种叫次嘴莺的鸟,然后介绍说这种鸟一生都在笼子里度过,从未在自然的天空中飞翔。
转载请注明原文地址:https://tihaiku.com/zcyy/3090090.html
相关试题推荐
Whatisscientists’aimofdrillingavolcano?[br][originaltext]16.Scientist
Whatisscientists’aimofdrillingavolcano?[br][originaltext]16.Scientist
Whatisscientists’aimofdrillingavolcano?[originaltext]16.ScientistsinI
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
Bycuttingoutthemiddlemanandbookingyourownflights,youcansaveup
随机试题
[originaltext]W:2millionhighschoolseniorsaregearingupthisfalltoappl
Diamondshavelittle_______valueandtheirpricedependsalmostentirelyonth
当前中国经济存在着下行的压力以及一些结构性问题,例如居民消费不足、投资过多和产能
某高层写字楼地下1层内走道长65m,宽2m,与走道相通的房间总面积800㎡,其中
成本控制方法中,()是对工程项目成本/进度进行综合控制的一种分析方法。A.工
侵权责任是指侵犯经纪服务合同所约定的债权之外的其他权利而应承担的民事责任,侵权责
下列选项中,构成非法拘禁罪的有()。A.甲(警察)因私怨与刘某发生口角,用手铐
关于经济影响分析的说法,错误的是( )。A.对于具有明显外部性影响的有形产品项目
下列各项活动中,属于监理工程师控制物资供应进度活动的是()A、审查物资供应情况分
实验研究和调查研究最根本的区别是A.调查研究也可以给予干预措施 B.实验研究可
最新回复
(
0
)