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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 week ago, I had the great pleasure of reading an e-book, When Money Talks, Listen! By Rich Ezzo.It took only about an hour to read.
When I first received a copy, I thought it was a Get Rich Quick type of publication.Nothing is wrong with Get Rich Quick, but my mind just doesn’t chase after dreams of wealth.I think that if God ever wants me to be rich, he knows where to find my purse.
When I began reading When Money Talks, Listen!, I was overjoyed to find that Rich Ezzo isn’t money hungry either.He, too, is hungry far more important than money.
Since I love this e-book so much, why wait a week to write the review? Simple.I wanted to see if the effect it had on me was a keeper.After reading the last word of the e-book, I totally agreed with the subtitle which promised to forever change the way we thought about money.I had so many thoughts running around my mind that I had to install(安装) a stoplight to stop some while others made their way into the picture, then I yielded(让路) them as a few ones arrived in town.I had a mental traffic jam, which only goes to show how slow the traffic usually is.
It has been a week and the effect is the same.I truly do look at money differently and have even done a few things differently this week.This is an e-book you’ll want to read, I promise.I often recommend books to my daughter, and this is one that I didn’t just “suggest”---I left it open at the bottom of the computer and told each one, “Read it, you’ll love it.”
I would never point someone in a direction I wouldn’t go myself.I urge you to visit the author’s website, Myster Money, and to download the e-book.You won’t regret it.
The author wrote this passage to _________
A.strongly recommend an e-book.
B.show the author's attitude to money.
C.introduce the general idea of an e-book.
D.point out Rich Ezzo isn't money hungry.
According to the passage, a Get Rich Quick type of publication ______.
A.is what the author really cares for
B.deals with how to make money
C.is also an e-book written by Rich Ezzo
D.is more popular than e-books
The author didn't write the review as soon as he finished reading the book because________.
A.he was too excited to write anything
B.he was not sure whether he did well
C.he had to wait for Rich Ezzo's permission
D.he wondered if the book would have long influence on him
By saying the underlined sentence in Paragraph 4, the author probably __________.
A.shows that the book brought him many new thoughts
B.shows how bad the traffic is in town
C.describes the difficulty in understanding the book
D.explains it's hard to change one's attitude to money
Which of the following is supported by the passage?
A.The author had known Rich Ezzo before.
B.The author hasn't dreamed of getting rich immediately.
C.The author always prefers e-books to paper books.
D.The author likes Get Rich Quick-type of publications.
查看习题详情和答案>>How to protect children Web fans from unsuitable material on-line while encouraging them to use the Internet has long been discussed in the U.S.
For some parents, the Internet can seem like a jungle, filled with danger for their children. But jungles contain wonders as well as dangers and with good guides, some education, and a few precautions(预防措施), the wilds of the Internet can be safely navigated(航行). “Kids have to be on-line. If we tell our kids they can’t have access(机会) to the Internet, we’re cutting them off from their future,” said an expert.
Most kids have started to use search engines. Many of them are great for finding tons of interesting Internet sites, and they can also locate places where you might not want your kids to go. There are search engines designed just for kids. A certain software contains only sites that have been selected as safe. The most popular way to limit access would be to use what is known as a “content screener(过滤器)”. But this can’t be wholly reliable(可靠), and the best thing parents can do is to talk to their kids and let them know what is OK or not OK to see or do on the Internet. Another way is that mum or dad is nearby when the child is surfing(浏览) the Internet.
A few other tips
●Don’t put the PC in a child’s room but keep it in an area where mum or dad can keep an eye on things. That also makes the Internet more of a family activity.
●Ask your child what he or she has been doing and about any friends they make on-line.
●Tell your child not to give on-line strangers personal information, especially like address and phone number.
●And tell your children never to talk to anyone they meet on-line over the phone, send them anything, accept anything from them or agree to meet with them unless you go along.
The passage is mainly about the subject of _______.
A. American children going on-line B. Internet in America
C. appreciating Internet D. opposing children’s on-line
The best way to protect children from improper material is _______.
A. to install(安装) a content screener on the computer
B. to buy some search engines for the children
C. to be nearby when they are surfing the Internet
D. to talk to the children and persuade them to tell right from wrong
Which of the following is right according to the passage?
A. Surfing the Internet is the best method of educating children.
B. Children’s not having access to Internet may have effect on their progress.
C. Using a content screener is most reliable for keeping children having access to Internet.
D. Searching engines can help children to select materials fit for them.
According to the passage, we can infer that _______.
A. soft wares fit for children want programming
B. a child who is on-line is in danger
C. Internet is a jungle full of danger
D. Internet contains a lot of harmful sites
查看习题详情和答案>>Where is that noise coming from? Not sure? Try living with your eyes closed for a few years.
Blind people are better at locating sounds than people who can see, a new study says, without the benefits of vision the ears seem to work much better.
Previous studies have shown that blind people are better than others at reaching out and touching the sources of sounds that are close by. Researchers from the University of Montreal wanted to see if blind people were also better at locating sounds that are far away.
Twenty-three blind people participated in the study. All had been sightless for at least 20 years. Fourteen of them had lost their vision before age 11. the rest went blind after age 16. The experiment also included 10 people who could see but were wearing blind-folds.
In one task, volunteers had to pick the direction of a sound coming from about 3 meters away. When the sound was in front of them or slightly off center in front, both groups performed equally well.
When sounds came from the side or the back, however, the blind group performed much better than the blindfolded group. The participants who had been blind since childhood did slightly better than those who lost their sight later.
Recognizing the locations of distant sounds can be a matter of life-or-death for blind people, say the researchers. Crossing the street, for instance, is much harder when you can’t see the cars coming.
Still, the researchers were surprised by how well the blind participants did, especially those who went blind after age 16. In another experiment, the scientists also found that parts of the brain that normally deal with visual information became active in locating sound in the people who were blind by age 11. These brain parts didn’t show sound-location activity in the other group of blind people or in the sighted people. The scientists now want to learn more about the working of brains of “late-onset” blind people.
The recent study shows blind people are better at telling __________.
A. The sources of loud sounds. B. the locations of distant sounds
C. the direction of sharp sounds D. the distance of a sound in front of them
Which would be a proper title for the passage?
A. A Research on Blind People B. Where is That Noise Coming from?
C. Hearing Better in the Dark D. What If Living Without Your Eyes?
If people were asked to tell the direction of a sound from the side, who would perform best?
A. Those who are blind. B. Those who have gone blind since children.
C. Those who went blind at age 16. D. Those who are blindfolded.
Which of the following is true according to the passage?
A. Whether to be able to locate the sounds can be of vital importance for the blind.
B. All the volunteers in the experiment are sightless.
C. All the participants did equally well when picking sounds from whatever direction.
D. The later people become blind, the better they can perform in telling the direction of sounds.
What do we know about that parts of brain dealing with visual information are active in locating sounds?
A. This happens in almost all the testers.
B. This only occurs in the people who were blind after age 16.
C. It remains nothing new to the scientists any more.
D. It remains a mystery why it is so.
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