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
专升本
(81)Why don’ t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for a
(81)Why don’ t birds get lost on their long flights from one place to another? Scientists have puzzled over this question for a
admin
2015-06-21
71
问题
(81)
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
第一段指出科学家最近才开始找到鸟类不迷失方向的谜的答案。因此可以得出B项是正确答案。
转载请注明原文地址:https://kaotiyun.com/show/c1TC777K
本试题收录于:
英语题库普高专升本分类
0
英语
普高专升本
相关试题推荐
OnesillyquestionIsimplycan’tstandis"Howdoyoufeel?"Usuallythequestionisaskedofamaninaction—amanonthego
It’s______(report)thatthepolicearesearchingtheforestforthesuspect.
Weather______(permit),theconferencewillbeheldasscheduled.
Hewassounwillingtogreetmeyesterday.I______himsomewayorother.
Cantreestalk?Yes—butnotinwords.Scientistshavereasonstobelievethattreesdocommunicatewitheachother.Notlonga
Whatisthe______(connect)betweenthetwoideas?
PersonalcomputersandtheInternetgivepeoplenewchoicesabouthowtospendtheirtime.Somemayusethisfreedomtoshar
Noonewas______intheaccident.
IwishI_____busyyesterday;Icouldhavehelpedyouwiththeproblem.
Thenumberofcemploycesatthefactory______toaminimumsoastolowerproductioncosts.
随机试题
女性肺结核患者,大咯血一小时,X线胸片示右肺上叶空洞性肺结核。BP12/8kPa(90/60mmHg),P100次/分钟,采取下列哪种治疗措施最恰当
设备及安装工程概算的编制方法主要有()和综合吨位指标法。
下列关于资产的企业所得税税务处理的说法,正确的有()。(2016年)
试述学生知、情、意、行统一发展的规律。
8,12,(),34,50,68
某班共有学生40人,其中喜欢打乒乓、篮球、排球的学生分别有35、33、32人,问这三项运动都喜欢的学生至少有多少人?
社会主义法律的规范作用根据其指向和侧重可以分为指引作用、预测作用、评价作用、强制作用和教育作用。除教育作用外,法律的其他作用中具有教育意义的是
设f(x)连续且F(x)=x2/(x-a)∫axf(t)dt,则为().
如果对数据的实时性要求比较高,但对数据的准确性要求相对较低(如在线电影),一般可在传输层采用______协议。
IcametoIndiaayearagotofindavillageinwhichIcouldliveandwrite,butitwasmanymonthsbeforeIsettleddown.
最新回复
(
0
)