Edmund Halley was an English scientist who lived over 200 years ago. He studied the
observations of comets(彗星) which other scientists had made. The orbit of one
particular comet was a very difficult mathematical problem. He could not figure it out.
Neither could other scientists who dealt with such problems.
However, Halley had a friend named Isaac Newton, who was a brilliant mathematician.
Newton thought he had already worked out that problem, but he could not find the
paper on which he had done it. He told Halley that the orbit of a comet had the shape
of an ellipse(椭圆形).
Now Halley set to work. He figured out(觯决,计算出) the orbits of some of the
comets that had been observed by scientists. He made a surprising discovery. The
comets that had appeared in the years 1531, 1607 and 1682 all had the same orbit.
Yet their appearances had been 75 to 76 years apart.
This seemed very strange to Halley. Three different comets followed the same orbit.
The more Halley thought about it, the more he thought that there had not been three
different comets, as people thought. He decided that they had simply seen the same
comet three times. The comet had gone away and had come back again.
It was an astonislung idea! Halley felt certain enough to make a prediction(顶言 )
of what would happen in the future. He decided that this comet would appear in the
year 1758. There were 53 years to go before Halley"s prediction could be tested.
In 1758 the comet appeared in the sky. Halley did not see it, for he had died some
years before. Ever since then that comet had been called Halley"s comet, in his honour.
B. the same comet appearing at different times
C. three different comets appearing three times
D.several comets appearing three times
B. by means of his own careful observation
C. by using the work of other scientists
D. by chance
B.1705
C.1706
D. 1707
B. the orbit of a comet
C. Newton and Halley
D. Halley and his discovery
grow in salty water. Most seaweed is red or brown in color. The Japanese people use this plant from the
sea in many ways. From it, they make a food called Kombu. Kombu is seaweed that has been dried,
cooked, and pressed together. Then it is dried again and cut into long pieces. The Japanese eat a lot of
Kombu and like it very much.
Japanese farmers often use seaweed as fertilizer. It makes their plants grow better. Many farmers
also find seaweed and make a fine food for their animals.
From seaweed the Japanese also get iodine (碘) , which they sell to other countries. Iodine is used
in many ways all over the world. It is used in making medicine. It is added to the salt we use at the table.
Scientists even use one form of iodine to "seed clouds" when they want rain to fall.
B. medicine
C. food
D. fertilizer
B. We eat it before meal.
C. We add it to the soup.
D. We add it to the salt we use at the table.
B. Kombu is made into medicine for farmers
C. the Japanese use seaweed in many ways
D. the Japanese eat a lot of Kombu
B. algae are plants from the sea
C. scientists could probably learn more about seaweed
D. seaweed is the only useful algae
basic needs for water-whether for drinking, agriculture, industry or the raising of fish will always have to
be met. Given that premise (前提) , there are two basic routes we can go:more equal access to water or
better engineering solutions.
Looking at the engineering solution first, a lot of my research concentrates on what happens to
wetlands when you build dams in river basins, particularly in Africa. The ecology of such areas is almost
entirely driven by the seasonal changes of the river-the pulse of the water. And the fact is that if you build
a dam, you generally spoil the downstream ecology. In the past, such problems have been hidden by a
lack of information. But in the near future, governments will have no excuse for their ignorance.
The engineers" ability to control water flows has created new kinds of unpredictability too. Dams in
Africa have meant fewer fish, less grazing and less flood- plain (洪泛区) agriculture-none of which were
expected. And their average economic life is assumed to be thirty years. Dams don"t exist forever, but
what will replace them is not clear.
The challenge for the future is to find new means of controlling water. Although GM technology
(转基因) will allow us to breed better dry land crops, there is no market for companies to develop
crops suitable for the micro-climates of the Sahel and elsewhere in Africa. Who is going to pay for
research on locally appropriate crops in the Third World?
B. The engineering solutions to water resource and their limitation.
C. The basic means of controlling water.
D. The challenge for developing crops.
B. More dams should be built in river basins.
C. More wetlands should be protected from destruction.
D. More dry-land crops could be developed in Africa.
3. The author suggests that governments will have no excuse for their careless ignorance in the future
because .
B. the ecological destruction will no longer be a problem in the future
C. the future is an information age
D. governments will face greater challenge in the future
B. less grazing land
C. less farming land
D. less floodplain agriculture
B. researchers have no interest in developing dry land crops
C. research on locally appropriate crops in the Third World may be profitable
D. There is less water resource in the Third World
resources of the sea were unlimited. For example, a noted biologist writing in the mid-19th century
commented that none of the great sea fisheries(渔业) are to be exhausted. Today though, there is
evidence that the resources land and the air, and that the endangered species (种类) include Herring
and Carp as well as the African Elephant, Indian Tiger, and the American Eagle.
Further, the threats to fish are more alarming in some ways than the threats to animals and birds.
This is because fish are a much needed food resource and people throughout the world depend on
fish as an important part of their dish, and the decline (下降) in the fish supply could have extensive
effects on hunger and population.
Fishermen in the North Atlantic alone annually harvest 20 billion pounds of fish to satisfy food
demands, but it is important to recognize that these practices cannot continue without depleting (耗尽)
fish storage within the next few years. Sea resources are rapidly declining in many parts of the world,
and the problem cannot he ignored (忽视) .
We can predict that food supplies in the sea can not last forever.
the sea?
B. Depleted.
C. Limited.
D. Unlimited.
B. The whole world.
C. Asia and America.
D. America.
B. None of the great sea fisheries are to be exhausted.
C. Fish supply has no effects on people.
D. Sea resources are important to people.
B. Threats to Animals and Birds
C. Sea Resources on the Decline
D. Protection of Fish
there for about a year, and then will be replaced with another group of pioneers. Building
the base on Mars will advance our knowledge of the solar system and aid in our
understanding of the earth.
We already know that Mars resembles the earth in many aspects : general size,
presence of water, lengthof day, range of temperatures. These resemblances have
caused many people to consider a centuries-long project: to transform Mars.
Transforming means alterinB a planet"s surface so that the Earth"s life forms can
survive there. This concept, previously found only in science fiction is now being
seriously considered by scientists.
Transforming Mars is theoretically simple : add nitrogen (氮气)and oxygen to the
atmosphere; pump water to the surface; and add the earth"s plants and animals in the
order in which they developed on the Earth. But it will take at least 300 years.
Some people think that such a project is too huge for humans to undertake, but
there are very good reasons to make the attempt. The earth now contains some 6
billion people and no one has any idea of how many humans the earth can support.
Our very existence and numbers are threatening many other species. We also have
had some experience with transforming our own planet : altering thelandscape ,
theatmosphereand the climate. Currently transforming earth has become a wiser activity
as we try to control global warming, air and water pollution, and" preserve some natural
living places.
While the possibility of such a project is small, it is not impossible. Even if earthbound
societies come and go in the next 300 years, the project can continue through the work
of the Mars settlers without the need for constant backing from the earth.
The future existence of all the people in our world may very well depend upon our ability
to transform Mars.
B. Changing.
C. Planting.
D. Building.
B. find out its similarity to the Earth
C. avoid the dying way of many other species
D. find on Mars living place for the increasing human beings
B. transforming Mars is theoretically simple
C. our existence and numbers are threatening many other species
D. the development of science and technology is very rapid
B. Negative.
C. Sceptical(怀疑的 ) .
D. Objective.
Most scientists agreed that cloning an entire human being-besides morally
questionable-was filled with technical problems. After all, research into animal cloning
has already shown that there are hundreds of failures, includingmanybadlydeformed
(畸形的)creatures that were usually miscarried.
Now comes word that it might be easier to clone humans than was previously
believed. People have a genetic quirk(怪癖) that might prevent some of the
developmental deformities associated with animal cloning. One gene, called IGF2R,
is normally imprinted in sheep, cows and mice but not in humans. Human clones would
always inherit non-imprinted IGF2R genes, so there would be no chance of a mix-up
and, their growth would be normal. But what of the other 49 0r so imprinted genes
(遗传基因 ) ?No one knows what troublethey might cause. So the fact humans have
one less imprinted gene than mice, sheep or cows means that human
cloningmightbemarginally (轻微地 ,很少地 ) easier , but not necessarily safer.
B. it faces no moral problems now
C. it might be easier but still not safer
D. it is proved by practice that it is easier, only not so safe
B. A genetic quirk.
C. A non-imprinted IGF2R.
D. Not clearly found.
B. 50.
C. 49.
D. 48.
B. it should be properly controlled
C. it should be stopped
D. it should be forbidden by law
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- 2—I hope you have a good weekend ! —_____.
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