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
60
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
WheredidJeffgettheinformation?Fromthe______.Whatdidthecataloguesincludeexceptvariousproducts?Detailedspecifi
Thefirststepinwisecarcareandserviceistobuyacarthatisinperfectcondition.Lookthecarovercarefullytomakesu
Thefirststepinwisecarcareandserviceistobuyacarthatisinperfectcondition.Lookthecarovercarefullytomakesu
A、Shetookcareofherdaughter.B、ShewenttotheEnglishcomer.C、Shelovedherdaughter.D、Shecaughtacold.AM:Didyougo
Thebossorderedthattheworkers______unlesstheyfinishthework.
A、Idon’tliketeaching.B、Iwilldoit.C、I’madoctor.D、I’mfine.CI’mateacher,whatdoyoudo?
Glassismadeofmixtureofmanysubstancesmeltedtogetherinalargefurnace.Themostimportantsubstanceissilicawhichis
假设你是李越,你的加拿大笔友Steve来信说,他和他的一些同学正在学中文,请你推荐两本学中文的词典。根据下表提供的信息请你给他写一封信。英汉/汉英词典新华字典收词(字)18,000(英语)20,000(汉语)10,000价格52元
A、Themanwantstowatchadanceperformanceintheevening.B、Thewomanlikesfootballgameverymuch.C、Thewomanandtheman
Businessmemoisfrequentlyusedincompanies.Itiscalledanintra-companycommunicationbecauseitisusedbypeopleintheir
随机试题
Windows桌面也是WindoWS系统中的一个文件夹。()
计算全厂串级用水量(循环系统水使用后复用于其他水系统的水量)、水循环率、生产水复用率、吨钢新水消耗、吨钢外排废水量、吨钢烟粉尘和SO2排放量、吨钢CODCr和石油排放量。确定大气环境影响评价范围、采用的预测方法并简要制订环境质量现状监测方案。
对有抗震设防要求的框架结构,其纵向受力钢筋的强度应满足设计要求;当设计无具体要求时,对一、二级抗震等级,检验所得的强度实测值应符合的规定有( )。
下列有关利润表的作用的表述中,错误的是()。
甲、乙均为1989年6月30日出生。甲于2007年年初参加工作,并已独立生活;乙在高中读书,靠父母生活。2007年5月31日,甲、乙在某饭店滋事,将邻桌的丙打伤,丙住院两个月后康复,于2007年8月1日向法院起诉,要求甲、乙赔偿医药费1万元,根据规定,本案
关于转让定价税制,下列说法中正确的是()。
【2017年(卷I)】股票回购对上市公司的影响是()。
西宁纸箱厂在青海省西宁市黄河路修建了一栋7层家属住宅楼,并在该楼4单元南侧阳台下修建了一个乒乓球台。由于该栋住宅楼窗户玻璃安装存在质量问题,数次发生玻璃坠落,住户普遍提出意见,但西宁纸箱厂未及时进行修缮。一年后,居住在该楼4单元6层南侧的被告陈应驹酗酒后关
Thedoctor’sadvicewasthatthepatient______atonce.
Spittinginpublichasbecomesociallyreprehensible-andevencriminal--inmanypartsofChinaaspublichealthauthorities
最新回复
(
0
)