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 a long
Why don’ t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for a long
admin
2019-09-23
85
问题
Why don’ t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for a long time. Now they’ re starting to fill in the blanks.
Not long ago, experiments showed that birds use the sun to guide them during daylight hours. How do birds 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. But it had 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 main means of navigation. When the stars are hidden by clouds, they apparently find their way by such landmarks as river courses, mountain ranges, coast lines. But when it’ s too dark to see these things, the doves circle helplessly, unable to find their way.
The reasons why birds don’t get lost on their 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
从文章第一段最后一句话“Now they’re starting to fill in the blanks.”可以得出答案B。A项“科学家们已经掌握多年了”;C项“每个人都知道”;D项“将有可能继续是一个谜”,都不符合文意。
转载请注明原文地址:https://kaotiyun.com/show/EfcK777K
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
Asthepopulationoftheworldkeepsongrowing,itgetsmoreandmoredifficulttofeedeveryone.TheUnitedStatesisoneoft
PressureCooker(压力锅)SafetyWhenyouarecookingwithapressurecooker,youshouldlearnafewcommonsense(常识)rules:1.
A、Thatblueshirt,please.B、No,youcan’tdoanythingforme.C、Yes,youcan.D、Icandoitbymyself.AWhatcanIdoforyou,
InsomepartoftheUnitedStates,farmingiseasy.Butfarminghasalwaysbeendifficultinthenortheasterncornerofthecoun
Thebrand(商标)nameputsafaceoneverycompany.NameslikeMcDonald’s,GM,Apple,Intel,andalargenumberofothershavelong
Thebrand(商标)nameputsafaceoneverycompany.NameslikeMcDonald’s,GM,Apple,Intel,andalargenumberofothershavelong
InNewYork,thereisnowaschoolwithnodailylessons,noclassteachers,notevenaschoolbuilding.The"school"isanowp
Glassismadeofmixtureofmanysubstancesmeltedtogetherinalargefurnace.Themostimportantsubstanceissilicawhichis
Educationhasbeenahigh-returnaswellasahigh-riskinvestmentfortheindividual.
Peaceanddevelopmentarethemainthemesofthetimes,anerafullofbothhopeandchallenges.
随机试题
在Excel单元格中______。
(2002年第153题)通过影响LES压.能促进胃食管反流病发生的是
图53~57中,为桑白皮的是()。
甲家的承包地被乙家的承包地所包围,在承包时,有一条小路通往甲家的承包地,甲为了拓宽道路,与乙签订了一份协议,拓宽道路一丈,甲一次性支付乙5000元。甲通过该合同所取得的权利为()。
国家总体规划和省级、县级、市县级总体规划分别由同级人民政府组织编制,并由同级()会同有关负责起草。
早强水泥砂浆锚杆的胶粘剂是由()和水组成。
两个以上法院都有管辖权的诉讼,原告可以向其中一个法院起诉(选择管辖);原告向两个以上有管辖权的法院起诉的,由最先立案的法院管辖。()
2011年,河北省农产品进出口总额41.1亿美元,同比增长21.2%,其中进口同比增长20.6%。2011年12月,河北省农产品出口、进口额均创历史新高,当月进出口4.5亿美元,同比增长30.7%,环比增长35.0%。其中出口1.6亿美元,同比增长8.
考察下列函数的极限是否存在.
安装Linux时必须创建的分区是(63)。
最新回复
(
0
)