首页
登录
职称英语
Why don’t birds get lost on their long migratory (迁徙) flight? Scientists have
Why don’t birds get lost on their long migratory (迁徙) flight? Scientists have
游客
2024-08-04
8
管理
问题
Why don’t birds get lost on their long migratory (迁徙) flight? Scientists have puzzled over this question for many years. Now they are beginning to fill in the blanks.
Not long ago, experiments showed that birds rely on the sun to guide them during day-light hours. But what about birds that fly mainly by night? Tests with artificial (人造的) stars have proved conclusively that certain night-flying birds are able to follow stars in their long-distance flights.
One such bird--a warbler--had spent its lifetime in a cage and had never flown under a natural sky. Yet it showed an inborn ability to use stars for guidance. The bird’s cage was placed under an artificial star-filled sky at migration time. 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.
Scientists think that warblers, when flying in daylight, use the sun for guidance. But stars are apparently their main means of directed flight in the night. What do they do when stars are hidden by clouds? Apparently, they find their way by such landmarks as mountain ranges, coast lines and river courses. But when it is too dark to see these, the warblers circle helplessly, unable to find their way. [br] What does "fill in the blanks" in the first paragraph mean?
选项
A、To do the exercise.
B、To take the test.
C、To know the right words.
D、To know the answer.
答案
D
解析
短语fill in the blanks的意思是“填空”。短文一开始就提出一个问题:鸟类在长途迁徙的过程中为什么不会迷路?然后说:很多年来科学家们对这个问题苦苦思索。因此,科学家们开始填补空白的意思就是找到了问题的答案。
转载请注明原文地址:https://tihaiku.com/zcyy/3704711.html
相关试题推荐
Thewomanwentthroughtwointerviewstobecomeaflightattendant.[br][origi
Thewomanwentthroughtwointerviewstobecomeaflightattendant.[br][origi
Thewomanwentthroughtwointerviewstobecomeaflightattendant.[originaltex
MightyFlightyAflycandoonethingextremelywell:
MightyFlightyAflycandoonethingextremelywell:
MightyFlightyAflycandoonethingextremelywell:
Athree-yearsearchforthemissingMalaysiaAirline’sflightMH370hasbeencal
Waybackin1582,someItalianscientistsnoted,withdismay,thattherewas
Waybackin1582,someItalianscientistsnoted,withdismay,thattherewas
Chocolatecouldsoonbeathingofthepast,afterscientistswarnedthatthe
随机试题
WhydoestheFoundationconcentrateitssupportonbasicratherthanapplied
Itispossibletolearnsomethingaboutmusicthroughbriefcontactwithit,
Previousstudieshaveshownthatparentswhoeatmorefastfoodandspen
对在合同约定的效益分享期内发生的期间费用划分不清的,应合理进行分摊,期间费用的分
中凹卧位需将床头及床尾抬起的角度分别为A.5°~10°,20°~30° B.1
属于抗病毒药的是()。A.诺氟沙星 B.吡哌酸 C.萘啶酸 D.阿昔洛韦
关于交感神经型颈椎病的临床表现与哪项无关A.视物模糊B.头痛C.出汗异常D.耳鸣
2020年,全年货物进出口总额321557亿元,比上年增长1.9%。其中,出口1
复制法的目的是A.增强疗效 B.改变药性 C.便于粉碎 D.降低或消除药物
长延时脱扣器用作电动机过载保护时,其整定电流应接近但不小于电动机的额定电流,且在
最新回复
(
0
)