Useful as half-sleeping might be, its only been found in birds and such water mammals(哺乳动物)as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasionally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds half-brain sleep is just the tip of the iceberg(冰山). He speculates that more examples may turn up when we take a closer look at other species.
11.A new study on birds sleep has revealed that .
A) half-brain sleep is found in a wide variety of birds
B) half-brain sleep is characterized by slow brain waves
C) birds can control their half-brain sleep consciously
D) birds seldom sleep with the whole of their brain at rest
12.According to the passage, birds often half sleep because .
A) they have to watch out for possible attacks
B) their brain hemispheres take turns to rest
C) the two halves of their brain are differently structured
D) they have to constantly keep an eye on their companions
13.The example of a bird sleeping in front of a mirror indicates that .
A) the phenomenon of birds dozing in pairs is widespread
【六级考试阅读理解真题精选练习13】相关文章:
最新
2016-10-18
2016-10-11
2016-10-11
2016-10-08
2016-09-30
2016-09-30