首页
登录
职称英语
Why don’t birds get lost on their long flights from one place to another? Scient
Why don’t birds get lost on their long flights from one place to another? Scient
游客
2023-10-03
34
管理
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 blares.
Not long ago, experiments showed that birds rely on the sun to guide them during daylight hours. But what about birds that 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. 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. When the stars are hidden by clouds, they apparently 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. [br] 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
本篇第一段说这个问题多年来使科学家迷惑不解,但随后又说:“Now they’re beginning to fill in the blanks.”这里“逐渐开始填补这些空白”意即“逐渐开始对所了解”。
转载请注明原文地址:https://tihaiku.com/zcyy/3067362.html
相关试题推荐
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Manhasabigbrain.Hecanthink,learnandspeak.Scientistsusedtothink
Scientistshavediscovered14kindsofvitamins.Ifwedonotgetenoughof
ShesaidshewouldliveinLondonfor______fourorfiveyears.A、anotherB、the
All______toHongKongweredelayedbecauseofbadweather.A、flyB、flightsC、flyi
NotonlyIbutalsoJaneandMaryaretiredofhavingonemeetingafteranother.
Aguestpayingfullfarecaninviteanotherguesttojointhetourathalfprice
Scientistsareeagertotalkwithotherscientistsworkingonsimilarproblems.
随机试题
Iwouldratherthey______tomaketheinvestigationtomorrow.A、cameB、comeC、shou
WriteinyourANSWERSHEETONEanoteofabout50-60wordstoafriendofyours
Thefollowingarealldynamicverbs(动态动词)EXCEPT_____.A、playB、leaveC、hitD、smel
Anewstudysuggeststhatthemoreteenagerswatchtelevision,themorelike
下列不属于女职工不得终止劳动合同的情况是()。A.女职工在孕期 B.女职
设信号的波特率为600Baud。采用幅度-相位复合调制技术,由4种幅度和8种相位
济南市气象局在市政府资金管理制度改革过程中,隐匿资金、突击发钱。根据群众举报,济
患者,男性,42岁,肝硬化病史5年,今日饮酒后突然大量呕血,伴神志恍惚、四肢湿冷
2012年全国国道网车流量较大的地区主要集中在北京、天津、上海、江苏、浙江、广东
根据《中华人民共和国保险法》的规定,除人寿保险业务外,经营其他保险业务,应当从当
最新回复
(
0
)