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
49
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
Thepopulationexplosionwillleadto______.Urbanizationcancauseenvironmentalproblemsbecause______.
______advertisingbringstheeconomiesofmasssellingtothemanufacturer,itproducesbenefitsfortheconsumeraswell.
I’llcontactmyofficeinLondonstraightawayand______toyou.
Woman:Itseemsthatyouenjoydoingsomanythingsatthesametime.Man:It’snotthatIlikethat,butthatIhavetoomany
Scholarsandstudentshavealwaysbeengreattravelers."Academicmobility"isnowoftenstatedasafundamentalnecessityfore
Beingagoodparentishardernowthanithaseverbeenbefore.Inpressurisedmodernlives,demandstobeafulfilledindividua
Banksarenotordinarilypreparedtopayoutallaccounts;theyrelyondepositorsnottodemandpaymentallatthesametime.I
Billisanexampleofaseverelydisabledpersonwhohasbecome______atmanysurvivalskills.
Thepressure______causesAmericanstobeenergetic,butitalsoputsthemunderaconstantemotionalstrain.
______theAtlanticOceancrossestheequator,thetradewindcausesaflowofwatertothewest.
随机试题
Windows系统安装并启动后,由系统安排在桌面上的图标是()。
犯罪的基本特征是()
A.肌张力先增强后降低B.肌张力先5纠氐后增强C.肌张力降低D.肌张力增强震颤麻痹患者常有
小儿五软脾肾两亏证的治法为小儿五迟心血不足证的治法是
某公司当前支付的红利为1元/股,第一年和第二年的盈利增长率和红利增长率均为20%,第三年盈利增长率和红利增长率下降到15%,从第四年开始,盈利增长率和红利增长率下降到6%,并一直维持这个水平。如果你的客户期望从该股票获得的必要回报率为10%,那么他愿意支付
王女士夫妇今年均为35岁,两人打算55岁退休,预计生活至85岁,王女士夫妇预计在55岁时的年支出为10万元,现在家庭储蓄为10万元。假设通货膨胀率保持3%不变,退休前,王女士家庭的投资收益率为8%,退休后,王女士家庭的投资收益率为3%。根据以上材料回答问
设计绩效管理程序时,对部门或者科室员工绩效考评过程所做的设计属于()
师德的灵魂是()。
新民住宅小区扩建后,新搬入的住户纷纷向房产承销公司投诉附近机场噪声太大,令人难以忍受。然而,老住户们并没有声援说他们同样感到噪声巨大。尽管房产承销公司宣称不会置住户的健康于不顾,但还是决定对投诉不准备采取措施。他们认为机场的噪声并不大,因为老住户并没有投
下列命令按钮的事件过程执行后,输出的结果是PrivateSubcommand1_click()Form=1To10Step2a=10Forn=1To10Srep2
最新回复
(
0
)