Birds that are half-asleep—with one brain hemisphere (半球) alert and the other sleeping—control which side of the brain remains awake, according to a new study of sleeping ducks.

    Earlier studies have documented half-brain sleep in a wide range of birds. The brain hemispheres take turns sinking into the sleep stage characterized by slow brain waves. The eye controlled by the sleeping hemisphere keeps shut, while the wakeful hemisphere’s eye stays open and alert. Birds also can sleep with both hemispheres resting at once.

    Decades of studies of bird groups led researchers to predict extra alertness in the end-of-the-row sleepers which tend to be attacked more easily. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.

    Also, birds napping at the end of the line depend on single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Turning 16 birds through the positions in a four-duck row, the researchers found that compared with 12 percent for birds in internal spots, outer birds half-asleep during some 32 percent of napping time.

    “We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness at the same time in different regions of the brain,” the researchers say.

    The results provide the best evidence for a long-standing assumption that single-hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the lookout side could be widespread, he predicts. He’s seen it in a pair of birds napping side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.

    Useful as half-sleeping might be, it’s only been found in birds and such water animals 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.” He supposes that more examples may turn up when we take a closer look at other species.

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

What is implied about the example of a bird’s sleeping in front of a mirror?

       A. An imagined companion gives the bird a sense of security.

       B. Birds prefer to sleep in pairs for the sake of their security.

       C. The phenomenon of birds napping in pairs is widespread.

D. A single pet bird enjoys seeing its own reflection in the mirror.

While sleeping, some water animals 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 ever-changing environment

       D. avoid being swept away by rapid currents

By saying “just the tip of the iceberg”, Siegel suggests that ______.

       A. half-brain sleep has something to do with icy weather

       B. the mystery of half-brain sleep is close to being solved

       C. most birds living in cold regions tend to be half sleepers

       D. half-brain sleep may exist among other species

Romance does not have to fizzle out（失败） in long-term relationships and progress into a companionship/friendship-type love, a new study has found. Romantic love can last a lifetime and lead to happier, healthier   1  .

"Many believe that   2  love is the same as passionate（多情的）love," said lead researcher Bianca P. Acevedo, PhD, then at Stony Brook University (currently at University of California, Santa Barbara). "It isn't. Romantic love has the intensity, engagement and sexual chemistry that passionate love has, minus the obsessive component（过度成分）. Passionate or obsessive love includes   3  of uncertainty and anxiety. This kind of love   4  drive the shorter relationships but not the longer ones."

These findings   5  in the March issue of Review of General Psychology, published by the American Psychological Association.

Acevedo and co-researcher Arthur Aron, PhD, reviewed 25 studies with 6,070 individuals in short- and long-term relationships to    6  whether romantic love is associated with more satisfaction. To determine this, they   7  the relationships in each of the studies as romantic, passionate (romantic with obsession) or friendship-like love and categorized them as long- or short-term.

The researchers looked at 17 short-term relationship studies, which included 18- to 23-year-old college students who were   8  , dating or married, with the average relationship lasting less than four years. They also   9  at 10 long-term relationship studies including middle-aged couples who were typically married 10 years or more. Two of the   10  ncluded both long- and short-term relationships in which it was possible to distinguish the two samples.

The review found that those who reported greater romantic love were more   11  in both the short- and long-term relationships. Companion-like love was only moderately   12  with satisfaction in both short- and long-term relationships. And those who reported greater passionate love in their relationships were more satisfied in the short term   13  to the long term.

Couples who reported more satisfaction in their relationships also   14  being happier and having higher self-esteem.

Feeling that a partner is "there for you"   15  or a good relationship, Acevedo said, and facilitates（促进） feelings of romantic love. On the other hand, "feelings of insecurity are generally associated with   16  satisfaction, and in some   17  may spark conflict in the relationship. This can manifest（表白） into obsessive love," she said.

This discovery may change people's   18  of what they want in long-term relationships. According to the authors, companionship love, which is what many couples see as the natural   19  of a successful relationship, may be an unnecessary compromise(妥协). "Couples should strive for love with all the trimmings（修剪）," Acevedo said. "And couples who've been together a long time and wish to get back their romantic edge should know it is an attainable（可达到的） goal that, like most good things in life,   20  energy and devotion."

(   ) 1. A. scholarships        B. friendships        C. relationships     D. companionships

(   ) 2. A. obsessive            B. romantic           C. passionate        D. companion

(   ) 3. A. feelings              B. factors              C. consequences    D. barriers

(   ) 4. A. contributes        B. helps               C. prevents           D. speeds

(   ) 5. A. occur                 B. take                 C. write               D. appear

(   ) 6. A. find out             B. work out          C. take out            D. bring out

(   ) 7. A. separated            B. classified          C. divided             D. cut

(   ) 8. A. alone                 B. lonely              C. single               D. unique

(   ) 9. A. glanced              B. glared              C. stared               D. looked

(   ) 10. A. findings           B. examinations     C. experiments      D. studies

(   ) 11. A. unpleased        B. disappointed     C. satisfied            D. desperate

(   ) 12. A. referred            B. associated        C. contended        D. conflicted

(   ) 13. A. compared        B. comparing               C. added               D. led

(   ) 14. A. reported           B. said                  C. believed           D. hoped

(   ) 15. A. takes               B. makes              C. means              D. depends

(   ) 16. A. higher              B. lower                      C. no                    D. much

(   ) 17. A. environments    B. states               C. air                   D. cases

(   ) 18. A. views                      B. expectations      C. remarks            D. statements

(   ) 19. A. progression       B. change             C. results              D. choice

(   ) 20. A. produces          B. satisfies            C. requires            D. consumes

On the table she found a piece of paper _________some puzzling secret codes.

A.which was written                                         B.that was written

C.on which were written                                          D.on that were written

The first true piece of sports equipment that man invented was the ball. In ancient(古代) Egypt, as everywhere, pitching (投掷)stones was a favorite children’s game. But a badly thrown rock could hurt(伤害) a child. Looking for something less dangerous to throw, the Egyptians made what were probably the first balls.

At first, balls were made of grass or leaves(树叶) held together by vines(藤). Later they were made of pieces of animal skin sewed together and stuffed(塞满 )with feathers or hay.

Even though the Egyptians were warlike, they found time for peaceful games. Before long they had developed a number of ball games, each with its own set of rules. Perhaps they played ball more for instruction than for fun. Ball playing was thought of mainly as a way to teach young men the speed and skill they would need for war.

The ball was probably invented because_______

A. throwing stones often caused injuries    B. throwing stones was not fun

C. games with stones did not have rules    D. rocks were too heavy to throw

The first balls were probably made of_______

A. animal skins stuffed with rocks         B. twists of hay

C. hides stuffed with hay or feathers       D. grass and leaves tied with vines

This selection says that the Egyptians played_____

A. many different games with balls        B. many different kinds of games

C. only one ball game                   D. different games with similar rules

The Egyptians thought that ball playing was _______

A. childish         B. difficult          C. not enjoyable       D. worthwhile

The best title for this selection is ______

A. The First Ball Games                B. How Egyptian Children Played Games

C. Egyptian Sports                    D. The Beginning of Sports

Younger adults who get either little sleep or a lot of it may see a greater expansion in their waistlines（腰围）over time, a study published suggests. Researchers found that among black and Hispanic adults younger than 40, those who typically slept for five hours or less each night had a greater accumulation of belly fat over the next five years, versus（相比于） those who averaged six or seven hours. Those who slept eight hours or more in bed each night also showed a bigger fat gain - but it was less obvious than that seen in "short sleepers."

The study, reported in the Journal Sleep, does not prove that too little or too much sleep directly leads to excess fat gain. But the findings support and extend those of other studies linking sleep duration - particularly a lack of sleep - to weight gain and even to higher risks of diabetes(糖尿病) and heart disease. Among participants younger than 40, the study found, those who said they slept for five hours or less each night gained more belly fat than those who averaged six or seven hours of sleep. On average, short sleepers showed a 32 percent gain in visceral（内脏的）fat, versus a 13 percent gain among those who slept six or seven hours per night, and a 22 percent increase among men and women who got at least eight hours of sleep each night. A similar pattern was seen with superficial abdominal（腹部）fat.

   The findings, according to lead researcher Dr. Kristen G. Hairston, support the belief that sleep habits affect weight and health in general. "Sleep is an important part of your overall health - not just in whether you're tired during the day," she said.

There may be indirect effects; people who get too little sleep may be too tired during the day to exercise, while those who spend a lot of time in bed may spend less time being active, relative to people who sleep fewer hours. Research also suggests that sleep loss alters people's levels of appetite-regulating hormones（荷尔蒙）- which could, in theory, cause them to overeat. Depression, which often affects people's sleep and has been linked to weight gain, could also be a factor, Hairston noted.

Who may have the higher risk of being fat over the next five years?

A. Jack, a Hispanic man, aged 35, sleeps for 3 hours every night.

B. Candy, a black woman, aged 41, sleeps for about 5 hours every night.

C. Bob, an American, aged 50, sleeps for more than 12 hours every day.

D. John, a student in Africa, sleeps for more than 6 hours every week.

What does the study, reported in the Journal Sleep find?

A. Too little or too much sleep directly gives rise to the fat gain.

B. People are subject to heart disease due to the lack of sleep.

C. It is admitted that sleep plays an important part in our health.

D. Researchers find a longer sleep time is better for our health.

What does the lead researcher Dr. Kristen G. Hairston agree with?

A. People should do some exercise in their daily life.

B. There is a close link between sleep habits and health.

C. More nutrition is greatly needed when we lack sleep.

D. More and more people tend to sleep less than before.

What can we infer from the passage?

A. Younger adults getting little or much sleep may become fat.

B. We are supposed to do exercise as much as possible to keep fit.

C. We should keep a good sleep habit to improve our health.

D. We have to spare no efforts to drive depression away.

What’s the best title of the passage?

A. Sleep Habits Linked to Fat Gain in Younger Adults.

B. Doing Exercise Is the Best Way to Keep Fit.

C. Our Waistlines Can Be Driven Away Right Now.

D. Diabetes No Longer bother all of Young People.