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
Why don’t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for many ye
Why don’t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for many ye
admin
2015-12-31
34
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 blanks.
Not long ago, experiments showed that birds rely on the sun to guide them during daylight hours. But what about birds that fly by 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 (鸽子) 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 (航行) only. When the stars are hidden by clouds, they seemingly 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.
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
文中第一段说:“从一个地方到另一个地方的长距离飞行中鸟为什么不会迷失方向?科学家们对此问题已困惑多年,现在他们找到了答案。”因此我们可以推断出,对这个问题的答案只是最近才被发现的。因此选项B正确。其他三个选项均与文章内容不符。
转载请注明原文地址:https://kaotiyun.com/show/i2PO777K
0
在职攻硕英语联考
相关试题推荐
Man:Doyouwanttoturnontheair-conditioneroropenthewindows?Woman:Ilovefreshairifyoudon’tmind.Question:Whatc
Thewordlibraryoriginallymeant______.Includingtalkingbooksintheircollectionsisagoodexampleof______.
Theword"extras"usedinthisstorymeanspeoplewho______.Thebesttitleforthisstorycouldbe______.
Inthispart,youaretowriteacompositionofnolessthan120wordsaboutWhetherCollegeStudentsShouldBeAllowedtoGetM
Theprofessorgave______instructiontothewholeclasssoastomakeeverystudentunderstandhowtoconducttheexperimentint
Scholarsandstudentshavealwaysbeengreattravelers."Academicmobility"isnowoftenstatedasafundamentalnecessityfore
Aristotle,theGreekphilosopher,summedupthefourbriefqualitiesofmoneysome2000yearsago.Itmustbelastingandeasy
Sincethelate1930’stheBureauofIndianAffairsoftheUnitedStateshasbeenworkingtopromotenativelanguageliteracyamo
Billisanexampleofaseverelydisabledpersonwhohasbecome______atmanysurvivalskills.
Thesecausesproducedthegreatchangeinthecountrythatmodernizedthe______ofhighereducationfromthemid-1860’stothem
随机试题
A、口服氯化钾B、苯妥英钠C、利多卡因D、阿托品E、地高辛抗体强心苷中毒(缓慢型心律失常)
焊缝的形式按不同的分类方法可分为哪几类?
金融远期合约与金融期货合约在流动性强弱方面的主要区别在于()
A.醇苷B.0-苷C.S-苷D.C-苷E.N-苷巴豆中含有
药品标签和说明书必须经医疗机构配制的制剂所使用的包材必须经
关于《保护工业产权巴黎公约》,下列说法中错误的是:
某测验的信度是0.8,现欲通过增加测验项目的长度的方法将信度提高到0.9,原测验的有20个题目,新测验需增加的题目数是
请根据以下各小题的要求设计VisualBasic应用程序(包括界面和代码)。(1)在名称为Form1的窗体上画两个标签(名称分别为lblName和lblAge,标题分别为“姓名”和“年龄”)、两个文本框(名称分别为txtName和txtAge,Text
A、我也很高兴B、是应该高兴C、就知道你们会赢D、没什么可高兴的D“……就……了呗”表示不在乎的语气,“有什么可高兴的”表示不应该高兴,所以答案是D。
Researchersinmanycountrieshaveobservedthatmiddleclasschildrenasagrouparemoresuccessfulintheeducationalsystem
最新回复
(
0
)