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
71
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.
During daylight hours, birds______.
选项
A、wheel back and forth for nothing
B、do not fly long distances
C、use sun for guidance
D、are quite likely to get lost
答案
C
解析
文中第二段第一句说:“不久以前的实验显示出:在白天鸟是依靠太阳对它们进行导航。”因此选项C正确。其余三个选项文章均未提及。
转载请注明原文地址:https://kaotiyun.com/show/Y2PO777K
0
在职攻硕英语联考
相关试题推荐
Alittlelearningisadangerousthing,foryoumightaswellnotknowathing______knowitonlyimperfectly.
______advertisingbringstheeconomiesofmasssellingtothemanufacturer,itproducesbenefitsfortheconsumeraswell.
StudentswhowanttoentertheUniversityofMontreal’sAthleticComplexneedmorethanjustaconventionalIDcard—theiridenti
WhatismostunusualaboutAmericansociety?Theauthor’sattitudetowardstheUSguncultureis______.
bothsidesaccepttheagreementalastingpeacebeestablishedinthisregion.
TeachersintheUnitedStatesearnlessrelativetonationalincomethantheircounter-partsinmanyindustrializedcountries,y
Theofficialwasarrestedforinabilityto______allhisfortunehehasenjoyed.
Manycriticsofthecurrentwelfaresystemarguethatexistingwelfareregulationsfosterfamilyinstability.Theymaintainthat
Itisdoubtfulwhetheranyonecanbeatruly______observerofevents.
Itisdifficulttoimaginewhatlifewouldbelikewithoutmemory.Themeaningsofthousandsofeverydayperceptions,thebases【
随机试题
清代顺治元年设立的收文机关是【】
衡量企业资金利用效果的一个重要指标是()
患者夜寐盗汗,五心烦热,两颧色红,口渴,舌红少苔,脉细数。治疗应首选()
债券资产组合收益评价的债券市场线方法包括的步骤有( )。
下列各类在用车船中,可以享受车船使用税减免税优惠政策()。
为帮助记忆我国传统的二十四节气。前人将其编成“二十四节气歌”.这种学习策略属于()。
A、 B、 C、 D、 C
甲从书画市场上购得乙的摄影作品《鸟巢》的原始底片,与其他摄影作品一起用于营利性展览。丙偷偷将《鸟巢》翻拍后以自己的名义刊登在某杂志上,丁经丙同意将刊登在该杂志上的《鸟巢》又制作成挂历销售。对此,下列错误的是()。
以下关于信息的描述,错误的是(1)________。
请你写一封邀请信,代表大连大新化学药品公司董事会(BoardofDalianDaxinChemicalsCorporation)邀请Mr.Chapman来本公司参加10周年纪念活动,时间从8月1号到3号。同时告诉他将安排一次他与总经理的见面会谈,
最新回复
(
0
)