A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces(熔炉) that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.

The death of a star is not a quiet event. First there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.

After the explosion gravity pulls in what’s left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so dense that a teaspoon of matter from it weighs billion of pounds.

The more the star shrinks, the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can go out. The star becomes black when there is no light. Then a black hole is born!

That’s what we know about black holes. What we don’t know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.

But if the black hole doesn’t keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world．They say that as the star disappears from our universe, it goes into another universe. In other words a black hole in our universe could turn into a “white hole” in a different universe. As the black hole swallows light, the white hole shines brightly — somewhere else. But where? A different place, perhaps, or a different time — many years in the past or future.

Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed．So far the time being, black hole must remain a mystery.

Black holes are a mystery—but that hasn’t stopped scientists from dreaming about them. One scientist suggested that in the future we might make use of the power of black holes. They would supply all of Earth’s energy needs, with plenty to spare. Another scientist wondered if a black hole could some day be used to swallow earthly waste—a sort of huge waste disposal (处理) in the sky!

When the star begins to die ______.

       A．there is no fuel left in it B．its outer layer goes into space first

       C．a huge explosion will happen        D．it doesn’t give off light any longer

Which of the following doesn’t help produce a black hole?

       A．The gravity inside the star is very strong.

       B．The light can’t go out of the star.

       C．The star becomes smaller and smaller

       D．The dying star shines very brightly.

The black hole ______.

       A．continues becoming smaller and smaller all the time

       B．goes into another universe and becomes a white hole

       C．can pull in everything we know of in the world

       D．will appear at another place at a different time

What’s the best title for this passage?

       A．A New Scientific Discovery: Black Holes

       B．How Do Black Holes Come Into Being?

       C．What Are Black Holes?

       D．Travel Through A Black Hole

A new study has found no evidence that sunscreen, commonly used to reduce the risk of skin cancer, actually increases the risk.

Researchers from the University of Iowa based their findings on a review of 18 earlier studies that looked at the association between sunscreen use and melanoma (黑素瘤)．They said that they found faults in studies that had reported associations between sunscreen use and higher risk of melanoma.

Most health experts believe that by protecting the skin from the harmful effects of the sun, sunscreen helps prevent skin cancer, which is increasing in incidence (发生率) faster than any other cancer in the United States.

But questions has been raised about sunscreen and whether it may has opposite effect, perhaps by allowing people to remain exposed to the sun longer without burning.

The researchers said that among the problems with some earlier studies is that they often failed to take into account that those people most at risk for skin cancer--- people with fair skin and freckles (雀斑), for example--- are more likely to use sunscreen．As a result, it may appear that sunscreen users get cancer more often.

The studies, which generally relied on volunteers to recall their sunscreen use, were also unable to prove how well the products had been applied, said the new study.

People with fair skin and freckles          .

       A．seldom use sunscreen             

       B．are more in danger of skin cancer

       C．can be free from the harm of the sun  

       D．often expose themselves to the sun

We can learn from the passage that          .

       A．sunscreen users get skin cancer more often

       B．the volunteers have proved the effect of sunscreen

       C．the new study was based on the experiences of volunteers

       D．the number of skin cancer patients is increasing in America

Which of the following can be the best title for this passage?

       A．Sunscreen to Prevent Skin Cancer   

       B．Sunscreen to Increase Skin Cancer

       C．Skin Cancer Caused by Sunscreen   

       D．Skin Cancer Caused by Freckles

A technique that controls immediate gas explosions by spraying them with large droplets of water is being tested by scientists at the University of Wales, United Kingdom．Instead of using the traditional fine water sprays when a gas leak is detected, the researchers have discovered that large droplets help to draw in some of the force of any explosion and provide a better way of controlling fire．

The research is based on studies made of the Piper Alpha oil rig （油井） explosion that occurred in the North Sea nine years ago killing 167 workers．The Welsh team found that by covering the gas-leak area with water droplets, the explosion and its effect can be greatly reduced．

Dr Gerand Thomas, a good lecturer in physics at the university’s Center for Explosion Studies, said that it was impossible to deal with gas explosions in the same way as fires because the whole event may only last a quarter of a second and normal water sprays do not have time to be effective．

Using the droplets of water to hold explosions resulted in the water being turned into a mist that allows some force of the explosion to be reduced．The mist slows down the combustion （燃烧） process and can stop a large amount of the gas igniting （点火,燃烧）, thus greatly reducing damage by limiting pressure development．With such a system, the operator has to decide at what point after a gas leak to activate the sprays．

The Center for Explosion Studies is the first of its kind in the UK and has been purposely-built for the study and implication of industrial explosions on land and sea．Research is developed to the causes of accidental explosions and they might be prevented．Full-sized imitative buildings can be built at the center where explosions and fires are created to test preventative equipment using sensors to monitor their efficiency．

Another area that the Welsh researchers have been looking at is how materials respond to explosions．The center also carries out research requested by individual customers．

Which of the following would be the best title for the passage?

     A．Piper Alpha Oil Rig Explosion

     B．Large Droplets of Water

     C．A New Way of Controlling Gas Explosions

     D．The center for Explosion Studies

The research finds that _____ in holding immediate explosion．

     A．small water sprays are better than large droplets of water

     B．small water sprays are not as good as large droplets of water

     C．both small water sprays and large droplets of water are good

     D．neither small water sprays nor large droplets of water is good

Dr Geraint Thomas implies that ______．

     A．normal water sprays can put out fire effectively

     B．gas explosions break out more quickly than fires

     C．fires are easier to be held than explosions

     D．gas explosions break out so quickly that there is no way to control it

Which of the following is not included in the research area of the Center for Explosion Studies?

     A．To test the result of gas explosion．

     B．To get some implications of industrial explosions on land and sea．

     C．To find out how materials respond to explosions．

    D．To find out when material respond to explosions．

A Brown University sleep researcher has some advice for people who run high schools: Don’t start classes so early in the morning. It may not be that the students who nod off at their desks are lazy. And it may not be that their parents have failed to enforce (确保) bedtime. Instead, it may be that biologically these sleepyhead students aren’t used to the early hour.

“Maybe these kids are being asked to rise at the wrong time for their bodies,” says Mary Carskadon, a professor looking at problem of adolescent  (青春期的) sleep at Brown’s School of Medicine.

Carskadon is trying to understand more about the effects of early school time in adolescents. And, at a more basic level. she and her team are trying to learn more about how the biological changes of adolescence affect sleep needs and patterns.

Carskadon says her work suggests that adolescents may need more sleep than they did at childhood, no less, as commonly thought.

Sleep patterns change during adolescence, as any parent of an adolescent can prove. Most adolescents prefer to stay up later at nigh and sleep later in the morning. But it’s not just a matter of choice –their bodies are going through a change of sleep patterns.

All of this makes the transfer from middle school to high school—which may start one hour earlier in the morning  ---- all the more difficult , Carskadon says. With their increased need for sleep and their biological clocks set on the “sleep late, rise late” pattern, adolescent are up against difficulties when it comes to trying to be up by 5 or 6 a.m. for a 7:30 a.m. first bell. A short sleep on a desktop may be their body’s way of saying. “I need a timeout.”

Carskadon suggests that high schools should not start classes so early in the morning because ________.

A. it is really tough for parents to enforce bedtime

B. it is biologically difficult for students to rise early

C. students work so late at night that they can’t get up early

D. students are so lazy that they don’t like to go to school early

The underlined phrase “nod off” most probably means “ _______”.

A. turn around    B. agree with others  C. fall asleep  D. refuse to work

What might be a reason for the hard transfer from middle school to high school?

A. Adolescents depend more on their parents.

B. Adolescents have to choose their sleep patterns.

C. Adolescents sleep better than they did at childhood.

D. Adolescents need more sleep than they used to.

What is the test mainly about?

A. Adolescent heath care.      B. Problems in adolescent learning.

C. Adolescent sleep difficulties.   D. Changes in adolescent sleep needs and patterns.

Some people believe that international sports creates goodwill between the nations and that if countries play games together they will learn to live together. Others say that the opposite is true: that international contests encourage false national pride and lead to misunderstanding and hatred. There is probably some truth in both arguments, but in recent years the Olympic Games have done little to support the view that sports encourages international brotherhood. Not only was there the tragic incident involving the murder of athletes, but the Games were also ruined by lesser incidents caused principally by minor national contests.

One country received its second-place medal with visible indignation after the hockey final. There had been noisy scenes at the end of the hockey match, the losers objecting to the final decisions. They were convinced that one of their goals should not have been disallowed and that their opponents’ victory was unfair. Their manager was in a rage when he said: “This wasn’t hockey. Hockey and the International Hockey Federation are finished.” The president of the Federation said later that such behavior could result in the suspension of the team for at least three years.

The American basketball team announced that they would not yield first place to Russia, after a disputable end to their contest. The game had ended in disturbance. It was thought at first that the United States had won, by a single point, but it was announced that there were three seconds still to play. A Russian player then threw the ball from one end of the court to the other, and another player popped it into the basket. It was the first time the USA had ever lost an Olympic basketball match. An appeal jury debated the matter for four and a half hours before announcing that the result would stand. The American players then voted not to receive the silver medals.

Incidents of this kind will continue as long as sport is played competitively rather than for the love of the game. The suggestion that athletes should compete as individuals, or in non-national teams, might be too much to hope for. But in the present organization of the Olympics there is far too much that encourages aggressive patriotism (爱国主义).

According to the author, the recent Olympic Games have ______.

A. created goodwill between nations          

B. bred only false national pride

C. barely showed any international friendship

D. led to more and more misunderstanding and hatred

What would the manager mean by saying, “...Hockey and the International Hockey Federation are finished”?

  A. His team would no longer take part in international games.

  B. Hockey and the Federation are both ruined by the unfair decisions.

  C. There should be no more hockey matches organized by the Federation.

  D. The Federation should be dissolved.

The basketball example implied that ______.

  A. too much patriotism was displayed in the incident

  B. the announcement to prolong the match was wrong

  C. the appeal jury was too hesitant in making the decision

  D. the American team was right in rejecting the silver medals

What conclusion can be drawn from the passage?

  A. The organization of the Olympic Games must be improved.

  B. Athletes should compete as individuals in the Olympic Games.

  C. Sports should be played competitively rather than for the love of the game.

  D. International contests are liable for misunderstanding between nations.