首页
登录
职称英语
Why don’t birds get lost on their long flights from one place to another? Scient
Why don’t birds get lost on their long flights from one place to another? Scient
游客
2023-10-03
14
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’re beginning to fill in the blares.
Not long ago, experiments showed that birds rely on the sun to guide them during daylight hours. But what about birds that fly at night? Tests with artificial stars have proved that certain night -- flying birds are able to follow the stars in their long-distance flights.
A dove had 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 an artificial 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 artificial stars caused a change in the direction of his flight.
But the stars are apparently their principal means of navigation. When the stars are hidden by clouds, they apparently find their way by such landmarks as mountain ranges, coast lines, and river courses. But when it’s too dark to see these, the doves circle helplessly, unable to find their way. [br] In total darkness, doves ______.
选项
A、use landmarks
B、don’t know which way to fly
C、fly back home
D、wait for the stars to appear
答案
B
解析
见本文最后一句:“But when it’s too dark to see these, the doves circle helplessly unable to find their way. ”
转载请注明原文地址:https://tihaiku.com/zcyy/3067366.html
相关试题推荐
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Accordingtoascientificresearch,smokingwill(short)______aperson’slifegr
Scientistshavediscovered14kindsofvitamins.Ifwedonotgetenoughof
Scientistshavediscovered14kindsofvitamins.Ifwedonotgetenoughof
All______toHongKongweredelayedbecauseofbadweather.A、flyB、flightsC、flyi
NotonlyIbutalsoJaneandMaryaretiredofhavingonemeetingafteranother.
Aguestpayingfullfarecaninviteanotherguesttojointhetourathalfprice
Ifnoonehasany______(object),we’llcontinuetomovetoanotherissue.objec
随机试题
[originaltext]Isittruethatyouwillfeelveryexcitedandhappywhenyou
Thefollowingchartshowssomeservicesofinsurancecompaniesthatpeoplet
PresidentJohnFitzgeralKennedywas_____________(被枪杀)byamantoday.shotand
Justbecausetheycan’tsingoperaorrideabicycledoesn’tmeanthata
A.呼吸衰竭 B.烟碱样症状 C.休克 D.毒蕈碱样症状 E.心衰胆碱酯
依据有关“建筑工程一切险”的规定,下列描述中正确的是( )。 A、投保人是发
类风湿关节炎最常累及的关节为A.肘关节 B.四肢小关节 C.膝关节 D.肩
把下面的图形分为两类,使每一类图形都有各自的共同特征或规律,分类正确的一项是:
(2022上半年真题)学生在学校学的主要是间接经验
由ISO/TC176制定的所有国际标准,统称为()。 A.产品质量标准
最新回复
(
0
)