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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
2011-03-26
74
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 age, 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. (76)
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.
(77)
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.
In the paragraph 3, "his outdoor cousins" means ______.
选项
A、other relatives
B、the other doves of the same brood (n. 窝)
C、doves under the natural sky
D、other birds in general
答案
C
解析
见第三段句子“The bird tried to fly in the same direction as that taken by his outdoor cousins.该鸟也竭力朝着鸟笼外面的伙伴飞行的方向飞。”可知,这里的外面的同伴指的就是空中飞翔的鸽子。
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