题目
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Red Dwarf stars (红矮星) can range in size from a hundred
times smaller than the sun, to only a couple of times smaller.
Because of their small size these stars burn their fuel very slowly,
which allows them to live a very long time. Some red dwarf stars
will live trillions of years before they run out of fuel.
Then why are red dwarf stars red? Beacuse red dwarf stars
only burn a little bit of fuel at a time, they are not very hot
compared to other stars. Think of a fire. The coolest part of the
fire at the top of the flame glows red, the hotter part in the middle
glows yellow, and the hottest part near the fuel glows blue. Stars
work the same way. Their temperatures determine what color they
will be. Thus we can determine how hot a star is just by looking at
its color.
Like the Sun, these medium(中等的) -sized stars are yellow
because they have a medium temperature. Their higher
temperature causes them to burn their fuel faster. This means they
will not live as long, only about 10 billion years or so. Near the
end of their lives, these medium-sized stars swell up becoming
very large. When this happens to the Sun it will grow to engulf(吞
没) even the Earth. Finally they shrink again, leaving behind
most of their gas. This gas forms a beautiful cloud around the star
called a Planetary Nebula(行星状星云) .
When will the Sun expand into a giant, and then shrink
leaving behind a planetary nebula?
Don"t worry. The sun is only about 5 billion years old. It still
has another 5 billion years before it will expand, and then turn
into a planetary nebula.
The Sun is so hot that when it dies, it will take a long time to
cool off. The sun will die in about 5 billion years, but it will still
glow for many billions of years after that. As it cools, it will be
what is called a white dwarf star. Finally, after billions maybe
even trillions of years, it will stop glowing, at that point it will be
what we call a black dwarf star. There are still no black dwarf
stars in the Universe.
B. Because they don"t move around.
C. Because they are cool.
D. Because they reflect light like the moon.
B. Why red dwarf stars burn a little fuel.
C. Why red dwarf stars are red.
D. How temperature determines the color.
B. Become larger.
C. Keep the same.
D. Grow high.
B. Yellow Stars
C. Planetary Nebula
D. Star Temperature
B. www. oceans. com
C. www. inventor. com
D. www. kidsastronomy. com
答案
核心考点
举一反三
research work a free 3 .While on the other hand, we are afraid that some of the
research will be 4 to our society. Thus, there should be a balance 5 the government whether or
not to 6 scientific research and development. 7 the scientific research is a job 8 , it is hard for
the government even the public to decide whether or not a research is 9 . But the scientific research, 10 something else, can"t go without creativity. 11 , as we all know, should not be limited. If we
12 , we will find 13 far-reaching research work came from free thinking, of which the 14 ideas may
seem fantastic at the beginning. Take Einstein 15 example.
He 16 the Theory of Relativity. His raw idea of the 17 was considered meaningless by the
public. No one at that time was able to 18 that this fantastic idea would lead to a 19 revolution
for Physics. 20 , free thinking without limit can encourage creativity to some extent (从某种程度上).
This is of great importance to the scientific research.
( )2. A. advised
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( )17. A. theory
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( )20. A. Thus
B. are advised
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B. When
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B. valuable
B. as for
B. Creativity
B. look out
B. a great deal of
B. great
B. for
B. catch up with
B. suggestion
B. say
B. rude
B. However
C. advise
C. atmosphere
C. benefit
C. for
C. block
C. Now that
C. in the advance
C. helpless
C. like
C. Creative
C. look into
C. a good few
C. terrible
C. at
C. put up with
C. thinking
C. speak
C. global
C. And
D. advising
D. discussion
D. harm
D. with
D. puzzle
D. As soon as
D. in advances
D. useless
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D. raw
D. from
D. came up with
D. advice
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D. terrible
D. But
from overheating: move it to a cooler spot. All you have to do is to
send a few comets (彗星) in the direction of Earth, and its orbit
will be changed. Our world will then be sent into a safer, colder
part of the solar system.
This idea for improving our climate comes from a group of US
National Aeronautics and Space Administration( NASA) engineers
and American astronomers. They say their plan could add another
six billion years to the useful lifetime of our planet-effectively
doubling its working life.
The plan put forward by Dr Laughlin, and his colleagues Don
Korycansky and Fred Adams, needs carefully directing a comet of
asteroid (小行星) so that it passes close by our planet and sends
some of its gravitational energy to Earth.
"Earth"s orbital speed would increase as a result and we
could move to a higher orbit away from the Sun," Laughlin said.
Engineers would then direct their comet so that it passed
close to Jupiter or Saturn. The comet would pick up energy from
one of these giant planets. Later its orbit would bring it back to
Earth, and the process would be repeated.
In the short term, the plan provides an ideal way to global
warming, although the team was actually concerned with a much
greater danger. The sun is certain to heat up in about a billion
years and so "seriously compromise" our biosphere (生物圈)-by
cooking us.
That"s why the group decided to try to save Earth.
The plan has one or two worrying aspects, however. For a
stairt, space engineers would have to be very careful about how they
directed their asteroid or comet towards Earth. The smallest
miscalculation (误算) in orbit could fire it straight at Earth-with
deadly results.
There is also the question of the Moon. As the scientific
American magazine points out, if Earth was pushed out of its current
position it is "most likely that the Moon would be stripped away
from Earth," it states. This would change our planet"s climate.
B. 6 billion
C. 18 billion
D. 24 billion
B. Earth"s working life is coming to an end soon.
C. Earth will become too hot for mankind to keep alive.
D. The moon is moving farther and farther away from Earth.
B. benefit
C. share
D. endanger
B. The comet might hit Earth and man might lose the moon.
C. The comet might hit Jupiter or Saturn and never return toEarth.
D. Earth"s working life might be greatly shortened.
When Geoff Marcy was 14, his parents bought him a telescope. Every night,he would
go onto the roof outside his window to see the wonders of the sky.
" What excited me most was whether there were planets in other solar systems where life
might exist," he says. "I decided to try to find planets orbiting other stars like our Sun. "
And he did. " My fellow researcher, Paul Butler, and I found our first planet in 1995 , " Dr Marcy
says. " We worked for ten years without finding anything! But we stuck with it, and our patience
paid off. "
Since then, the two scientists have discovered 65 of the more than 100 planets found orbiting other
stars. Dr Marcy and Dr Butler also spotted the first "family" of three planets. In June 2002 they
announced another discovery: a Jupiter-like(像木星一样的) planet orbiting star 55 Cancri.
At first, the two researchers found only planets that orbit close to stars. Recently, the scientists
found planets farther out. The planet orbiting 55 Cancri is a major breakthrough: it is the first sighting
of a large gas planet about the same distance from the star as Jupiter is from the Sun.
Why is this important? Scientists think that life on Earth may exist because of two special features
(特征) in our solar system.
The first is Jupiter.
"Because it"s so big, Jupiter pulls comets (彗星) and asteroids (小行星) , or they all come and hit
the Earth. " Dr Marcy explains. "Without Jupiter, life on Earth would likely have been destroyed. "
A second feature is that Earth is a rocky planet where liquid water, which is necessary for life, can
exist. Unlike gas planets, rocky planets like Earth have surfaces where water can gather in pools and
seas, which may support life. A huge space exists between the Jupiter-like planet and two other planets
that lie close
to 55 Cancri. Is there an Earth-like planet in the space, too small for us to notice? If so, says Dr Marcy," We would have two striking similarities to our solar system: a Jupiter-like planet and an Earth-like planet. And there may be life ! "
B. He is from a scientist family.
C. He dislikes working with Paul Butler.
D. He is interested in finding life in outer space.
B. The planet is close to star 55 Cancri.
C. The planet proves to be a gas planet.
D. The planet is as large as Jupiter.
B. 69.
C. 66.
D. 65.
B. he has discovered an Earth-like planet there
C. he has discovered a rocky planet there
D. he has found signs of life in the system
wrote a book about them called Principles of Geology. The earth,
according to Lyell, was not only thousands of years old, it was
millions of years old. As to (关于) the common belief that changes
in the earth"s surface happen suddenly because of a single
earthquake or flood, he said that this might happen once in a
while, but usually these changes took place very slowly. He
believed that the surface of the earth had been changing from the
beginning of time. The changes, he said, were caused by the long-
term action of the winds and seas, and by forces such as volcanoes
breaking out under the earth"s surface. Once in a great while he
thought, a mountain might appear for the first time after an
earthquake. But usually mountains would rise slowly and steadily.
Professor Henslow was interested in Lyell"s ideas, but he did
not actually believe them. Charles Darwin could not make up his
mind about them. But they set him thinking along lines which would
later change the beliefs of thoughtful people all over the world.
At Cambridge ,Charles Darwin studied just enough to pass the
examination, and received his college degree in 1831. During this
time, he had become more and more interested in geology. At the
end of the school year, he went to North Wales with one of his
teachers to examine the rock formations (构成) and to search for
fossils (化石). Fossils are the remains of ancient living things.
They are usually found fixed in rocks in the earth"s crust (地壳).
Fossils may be of animals, such as fish, insects, birds, or
humans. They may be of plants from tiny leaves to huge trees.
When a living creatures dies, it usually decays (腐烂) or is
eaten by animals. However, if it sinks into a riverbed or is quickly
covered by the blowing sands of a desert storm, the bones are kept
up in the earth. Over many years the soft inner parts of a bone
disappear, leaving the inside bellow. Water containing mineral
enters into the hollow. Slowly the mineral hardens and makes the
bone hard and heavy, like stone.
B. past some experiences of big flood
C. over a very long period of years
D. because of several big earthquakes
B. more slowly than suddenly
C. more by an earthquake than by winds
D. more quickly than steadily
B. did made up his mind not to accept Lyell"s ideas
C. thought about what the world was then
D. thought over Lyell"s ideas and developed them
B. appreciate the rock information
C. do research work into dead animals
D. look for plants from tiny leaves to huge trees
orbit for a few days or more. And this stands to reason, if you"re
paying $ 20,000 for your trip to orbit! So in order for tourism to
reach its full potential there"s going to be a need for orbital
accommodation-or space hotels. What would a space hotel
actually be like to visit? Hotels in orbit will offer the services you
expect from a hotel-private rooms, meals, bars. But they"ll also
offer two unique experiences: impressive views-of Earth and
space~ and the endless entertainment of living in zero gravity-
including sports and other activities that make use of this.
The hotels themselves will vary greatly-from being quite
simple in the early days to huge luxury structures at a later date.
It"s actually surprising that as later as 1997,very few designs for
space hotels were published. This is mainly because those who
might be expected to design them haven"t expected lauch costs to
come down far enough to make them possible.
Lots of people who"ve been to space have described vividly
what it"s like to live in zero gravity. There are obviously all sorts of
possibilities for dancing, gymnastics, and zero-G sports. Luckily,
you don"t need to sleep much living in zero gravity, so you"ll have
plenty of time for relaxing by hanging out in a bar with a window
looking down at the turning Earth below.
Of course all good things have come to an end, unfortunately.
And so after a few days you"ll find yourself heading back though
you"ll be much more expert at exercising in zero gravity than you
were when you arrived. You"ll be thinking how soon you can save
up enough to get back up again-or maybe you should change jobs
to get to work in an orbiting hotel!
B. they would find the possible life in other star systems
C. they could enjoy the luxury of space hotels
D. they want to realise the full potential of tourism
B. The special views.
C. The relaxation in a bar.
D. The space walk.
B. What are the unique experiences that space hotels will offer?
C. Why were there not many published designs for space hotels?
D. How can the travelers enjoy themselves in space hotels?
B. the ways of living in space hotels
C. zero gravity and space hotels
D. the description of space hotels
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