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
2009-05-28
23
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 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.
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 are beginning to fill in the blanks,这里"逐渐开始填补这些空白"意为"逐渐开始对此有所了解"。
转载请注明原文地址:https://kaotiyun.com/show/FRwK777K
本试题收录于:
大学英语三级B级题库大学英语三级分类
0
大学英语三级B级
大学英语三级
相关试题推荐
DictationListentothepassage.Forquestions21—25,fillintheblankswiththeexactwordsorphrasesyouhear.Companiessh
DictationListentothepassage.Forquestions21—25,fillintheblankswiththeexactwordsorphrasesyouhear.Companiessh
Owningacatcanreducetheriskofheartattacksandstrokesbymorethanathird,researchershavefound.Scientistssaidthat
Afewyearsago,ItookasightseeingtriptoWashingtonDC.Isawmanyofournation’streasures,andIalsosawalotofourf
Afewyearsago,ItookasightseeingtriptoWashingtonDC.Isawmanyofournation’streasures,andIalsosawalotofourf
Last,weekmybrotherandIdecidedtopaintourbedroomwhileourparentsareoutfortheday.Ourparentsusuallyhavethe【M1
A、Anhonestpersonnevertellslies.B、Oneshouldn’tbreakapromiseeasily.C、Aninvitationisasignoffriendship.D、Somethin
A、Theyhavemoretimetocontactwithothers.B、Theyfeelfreefromworkrestrictions..C、Theyhaveavisionofanewjob.D、The
Shedidn’treceivetheapplicationform;it______tothewrongaddress.
SitnexttoanAmericanonanairplaneandhewillimmediatelyaddressyoubyyourfirstname.
随机试题
垄断利润的主要来源()
主湿证的脉象有
黑白花奶牛,3岁,采食后突然发病。反刍停止,喜卧,呻吟,磨牙,排便量减少,精神沉郁,腹部膨胀,左欣窝扁平,听诊瘤胃蠕动音消失。对本病有诊断意义的瘤胃内容物呈()
以下表现与格林-巴利综合征无关的是
[2005年第19题]设A=,其中ai≠0,bj≠0(i=1,2,…,n),则矩阵A的秩等于()。
“进口口岸”栏应填报()。9.“成交方式”栏应填报()。
根据以下资料.回答下列问题。2011年1—8月份,全国规模以上工业企业实现利润32281亿元,同比增长28.2%。在规模以上工业企业中,国有及国有控股企业实现利润10175亿元,同比增长20.6%;集体企业实现利润519亿元,同比增长3
在下列一首七律的横线处填上一句最贴切的句子,正确的一项是()。江风送月海门东,人到江心月正中。______________,一船鸡犬欲腾空。帆如云气吹将灭,灯近银河色不红。如此宵征信奇绝,三更三点水精宫。
计算机系统软件中,最基本、最核心的软件是()。
A、It’swindy.B、It’scloudy.C、It’srainy.D、It’sshiny.D事实细节题。对于Albuquerque的天气,女士提到了Fineweather,显然应该是阳光明媚才对。
最新回复
(
0
)