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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
查看习题详情和答案>>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
查看习题详情和答案>>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
查看习题详情和答案>>A new study shows one of the largest glaciers① in Greenland is becoming smaller and speeding to the sea faster than scientists expected. If it continues, Greenland itself could become much smaller during this century and global seas could rise as much as 3 feet.
The rates② of change that we’re noticing are much higher than expected. If these rates continue, it is not unlikely that Greenland could shrink③ by several tens of percent this century. However, it’s not known how quickly this coastal response of the Greenland ice sheet melting will have an effect on the vast inland ice.
Greenland is the world’s largest island, covering an area more than three times the size of Texas. Some 81 percent of it is covered by ice, and there are many glaciers. Glaciers are like slow-moving rivers of ice. Where a glacier meets the sea, its weight keeps it firmly resting on the bottom. A glacier’s front is the point where the water is deep enough that the glacier floats.
Since the 1970s, the front of Helheim stayed in the same place. Then it began melting rapidly, moving back 4.5 miles from 2001 through this past summer. It has also grown thinner, from top to bottom, by more than 130 feet since 2001. And over these past four years, its trip to the sea has sped up from about 70 feet per day to nearly 110.
The melting is driven by a warmer climate. Temperatures in Greenland have risen more than five degrees Fahrenheit in the last decade. Since most of Greenland’s ice is on land, seas will rise as the ice melts. If all Greenland’s ice sheet melted, oceans would be 15-20 feet higher. Nobody expects that to happen anytime soon.
Notes:
① glacier n. 冰川
② rate n. 比率
③ shrink v. 缩小
1. Which of the following about the glaciers is TRUE?
A. Glaciers only lie in Greenland. B. Water in glaciers is more than sea water.
C. Glaciers sometimes float on the water. D. Glaciers can increase the water level of lakes.
2. According to the text, we know that Greenland ______.
A. belongs to Canada B. is the largest island in North America
C. is all covered with glaciers D. is sinking under the sea level
3. Which of the following may be the result of the disappearing of Greenland glaciers?
A. the climate of the world will be warmer.
B. the glaciers in other area will be bigger.
C. It will be easy for explorers to visit the island.
D. Some coastal cities may be under the sea.
查看习题详情和答案>>A 10-year-old boy fatally shot his father Friday, striking him several times as he sat in the front seat of a SUV to pick up the boy from his mother’s home for a weekend visit.
The incident happened about 3:45 p.m. on a cul-de-sac (死胡同) in the 1700 block of Cedar Cove Court, said Sgt. B. E. Williams of the Harris County Sheriff’s Department.
An investigation found that Rick James Lohstroh, 41, was shot by his son, who was sitting in the back seat of the man’s Toyota 4-Runner, said Sgt. B. E. Williams of the Harris County Sheriff’s Department. The shooting took place outside the home of Lohstroh’s ex-wife, where the boy lives with his mother and a 7-year-old brother.
“We’re not certain of anything until we finish our investigation,” Williams said. “The information we have at this time is that the 10-year-old did fire the weapon.”
The mother and the 7-year-old were inside the house when the shooting occurred, said Williams.
Williams said the gun belonged to the boy’s mother. After firing shots through the back seat, the boy exited(退出) the back of the vehicle and continued to fire at the car.
The man died on the way to Memorial Herman Hospital. Lohstroh was a doctor at the University of Texas Medical Branch. The man and woman shared custody（监护）of the children. Williams said the mother and the boy were still in the home talking to investigators Friday night.
Neighbors described the family as being quiet and keeping to themselves.
Justin Gray, 17, was walking in the neighborhood when he heard gunshots. “We’ve had a suicide（自杀）in this neighborhood once, but never anything like this,” Gray said.
The best title for the news should be .
A. A Boy Shot His Father B. Shooting Kill a Father
C. An Unbelievable Tragedy D. A Ten-Year-Old Boy’s Cruelty
Which of the following is TRUE according to the news?
A. The father is not responsible for the boy.
B. The family don’t like associating with their neighbours.
C. The boy lives with Rick James Lohstroh.
D. The boy has no brothers or sisters.
What can we infer from the report?
A. The tragedy happened because the boy had seen too many films showing violence.
B. The boy killed his father after he quarreled with his father.
C. Such things often occurred in this neighbourhood.
D. The boy’s parents got divorced (离婚).
The reason why the boy shot his father .
A. is clear B. can’t be made out C. is not known D. is quite simple
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