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
2024-07-19
5
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] The reasons why birds don’t get lost on long flights ______.
选项
A、have been known to scientists for years
B、have only recently been discovered
C、are known by everyone
D、will probably remain a mystery
答案
B
解析
本篇第一段说这个问题多年来使科学家迷惑不解,但随后又说:“Now they’re beginning to fill in the blanks.”这里“逐渐开始填补这些空白”意即“逐渐开始对所了解”。
转载请注明原文地址:https://tihaiku.com/zcyy/3683624.html
相关试题推荐
NotonlyIbutalsoJaneandMaryaretiredofhavingonemeetingafteranother.
Scientistshavediscovered14kindsofvitamins.Ifwedonotgetenoughof
Scientistshavediscovered14kindsofvitamins.Ifwedonotgetenoughof
Scientistshavediscovered14kindsofvitamins.Ifwedonotgetenoughof
ShesaidshewouldliveinLondonfor______fourorfiveyears.A、anotherB、the
NotonlyIbutalsoJaneandMaryaretiredofhavingonemeetingafteranother.
Aguestpayingfullfarecaninviteanotherguesttojointhetourathalfprice
Ifnoonehasany______(object),we’llcontinuetomovetoanotherissue.objec
Theoldman______sonisafamousscientistneverreceivedanyeducation.A、what
Whydon’tbirdsgetlostontheirlongflightsfromoneplacetoanother?S
随机试题
NewZealandgaineditsindependenceinA、1840.B、1907.C、1931D、1947B本题考查新西兰历史知识
Thecompetitionamongproducersofpersonalcomputersisessentiallyarace
Forsomeeducators,thereisnothingwrongwithfunandgames.Agroupcalle
对现场工艺试验质量控制时,当出现必要情况,()组织相关单位及有关专家共同观
安装工程的区段划分要与土建工程的区段划分保持一致,以保证项目建设按期完成。
下面是2015年5月25日W、M、K、Q四个城市的天气预报:四个城市中有三种天气
A
下列资产中属于国有资产的有()。A:股份制企业中的国家股B:国有企业向独立于自
下列各句中存在歧义的一句是( )。A.这一场关于宗教的争辩,虽说引得甚嚣尘上,
下列各项不属于灼烫危险因素的是()。A.盐酸引起的灼伤 B.激光灼伤 C.
最新回复
(
0
)