Useful as halfsleeping might be, it's 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' halfbrain 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) halfbrain sleep is found in a wide variety of birds
B) halfbrain sleep is characterized by slow brain waves
C) birds can control their halfbrain 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
B) birds prefer to sleep in pairs for the sake of security
C) even an imagined companion gives the bird a sense of security
D) a single pet bird enjoys seeing its own reflection in the mirror
14. While sleeping, some water mammals tend to keep half awake in order to ________ .
A) alert themselves to the approaching enemy
B) emerge from water now and then to breathe
C) be sensitive to the everchanging environment
D) avoid being swept away by rapid currents
15. By "just the tip of the iceberg"( Line 2, Para. 8), Siegel suggests that________ .
A) halfbrain sleep has something to do with icy weather
B) the mystery of halfbrain sleep is close to being solved
C) most birds living in cold regions tend to be half sleepers
D) halfbrain sleep is a phenomenon that could exist among other species
Passage Two
Questions 16 to 20 are based on the following passage.
A nine year old schoolgirl singlehandedly cooks up a sciencefair experiment that ends up debunking(揭穿……的真相) a widely practiced medical treatment. Emily Rosa's target was a practice known as therapeutic(治疗的) touch (TT for short), whose advocates manipulate patients' "energy field"to make them feel better and even, say some, to cure them of various ills. Yet Emily's test shows that these energy fields can't be detected, even by trained TT practitioners (行医者). Obviously mindful of the publicity value of the situation, Journal editor George Lundberg appeared on TV to declare, "Age doesn't matter. It's good science that matters, and this is good science."
Emily's mother Linda Rosa, a registered nurse, has been campaigning against TT for nearly a decade. Linda first thought about TT in the late '80s, when she learned it was on the approved list for continuing nursing education in Colorado. Its 100,000 trained practitioners (48,000 in the U. S.) don't even touch their patients. Instead, they waved their hands a few inches from the patient's body, pushing energy fields around until they' re in "balance." TT advocates say these manipulations can help heal wounds, relieve Pain and reduce fever. The claims are taken seriously enough that TT therapists are frequently hired by leading hospitals, at up to $ 70 an hour, to smooth patients' energy, sometimes during surgery.
Yet Rosa could not find any evidence that it works. To provide such proof,TT therapists would have to sit down for independent testing——something they haven't been eager to do, even though James Randi has offered more than $1 million to anyone who can demonstrate the existence of a human energy field. (He's had one taker so far. She failed.) A skeptic might conclude that TT practitioners are afraid to lay their beliefs on the line. But who could turn down an innocentfourthgrader? Says Emily:"I think they didn't take me very seriously because I'm a kid."
The experiment was straight forward: 21 TT therapists stuck their hands, palms up, through a screen. Emily held her own hand over one of theirsleft or rightand the practitioners had to say which hand it was. When the results were recorded, they'd done no better than they would have by s
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