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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 study of English learning problems was carried out among a total of 106 foreign students. It shows that most students considered understanding spoken English to be their biggest problem on arrival. This was followed by speaking. Writing increased as a problem as students discovered difficulties in writing papers that they were now expected to hand in. Reading remained as a significant(显著的) problem.
The information gained helped us in determining where special attention should be paid in our course. Although many students have chosen to join the course with a reasonable motivation(动机), we considered it important to note what seemed to encourage interest. Nearly all the students have experienced some kind of grammar-based English teaching in their own country. To use the same method would be self-defeating because it might reduce motivation, especially if it has failed in the past. Therefore a different method may help because it is different.
Variety of activity was also seen as a way of maintaining(保持) or increasing motivation. Several years ago we had one timetable that operated throughout, but we soon found that both the students and the teachers lost interest by about halfway through the ten weeks. This led us to a major re-think, so finally we brought it into line with the expressed language needs of the students.
10. What is the text mainly about?
A. Foreign students have more problems.
B. There are many ways to improve English.
C. Teaching should meet students’ needs.
D. English learning problems should be studied again.
11. Writing became a bigger problem when foreign students________.
A. had to write their papers
B. became better at speaking
C. became less interested in reading
D. had fewer problems with listening
12. We may infer from the last two paragraphs that ________.
A. different teaching methods should be used
B. grammar-based teaching seems to be encouraging
C. English courses are necessary for foreign students
D. teaching content should be changed halfway.
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
A higher reading rate, with no loss of comprehension, will help you in other subjects as well as in English, and the general principles apply to any language. Naturally, you will not read every book at the same speed. You would expect to read a newspaper, for example, much more rapidly than a physics or economics textbook-but you can raise your average reading speed over the whole range of materials you wish to cover so that the percentage gained will be the same whatever kind of reading you are concerned with.
The reading passages which follow are all of an average level of difficulty for your stage of instruction. They are all about five hundred words long. They are about topics of general interest which do not require a great deal of specialized knowledge. Thus they fall between the kind of reading you might find in your textbooks and the much less demanding kind you will find in a newspaper or light novel. If you read this kind of English, with understanding at four hundred words per minute, you might skim (浏览) through a newspaper at perhaps 650-700, while with a difficult textbook you might drop to two hundred or two hundred and fifty.
Perhaps you would like to know what reading speeds are common among native English-speaking university students and how those speeds can be improved. Tests in Minnesota, USA, for example, have shown that students without special training can read English of average difficulty, for example, Tolstoy's War and Peace in translation, at speeds of between 240 and 250 words per minute with about seventy percent comprehension. Students in Minnesota claim that after twelve half-hour lessons, once a week, the reading speed can be increased, with no loss of comprehension, to around five hundred words per minute.
According to the passage, the purpose of effective reading with higher speed is most likely to help you ________.
A. only in your reading of a physics textbook
B. improve your understanding of an economics textbook
C. not only in your language study but also in other subjects
D. choose the suitable materials to read
Which of the following does not describe the types of reading materials mentioned in the second paragraph?
A. Those beyond one's reading comprehension.
B. Those concerned with common knowledge.
C. Those without much demand for specialized knowledge.
D. Those with the length of about five hundred words.
The average speed of untrained native speakers in the University of Minnesota is ________.
A. about 300 words per minute
B. about 245 words per minute
C. about 650-700 words per minute
D. about 500 words per minute
According to the passage, how fast can you expect to read after you have attended twelve half-hour lessons in the University of Minnesota?
A. You can increase your reading speed by three times.
B. No real increase in reading speed can be achieved.
C. Yon can increase your reading speed by four times.
D. You can double your reading speed.
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