earth. Most of it will miss our planet, but two pieces will probably hit the southern half
of the earth.
On 17 July, a piece four kilometers wide enters the earth"s atmosphere(大气层) with a
massive explosion. About half of the piece is destroyed, but the remaining part hits the
South Atlantic at 200 times the speed of sound. The sea boils and a huge hole is made in
the sea bed. Huge waves are created and spread outwards from the hole. The wall of water,
a kilometer high, rushes towards southern Africa at 800 kilometers an hour. Cities on the
African coast are totally destroyed and millions of people are drowned.
Before the waves reach South America, the second piece of the comet lands in
Argentina. Earthquakes and volcanoes are set off in the Andes Mountains. The shock
waves move north into Califomia and all around the Pacific Ocean. The cities of Los
Angeles, San Francisco and Tokyo are completely destroyed by earthquakes. Millions
of people in the southern half of the earth are already dead, but the north won"t escape
for long. Because of the explosions, the sun is hidden by clouds of dust, temperatures
around the world fall to almost zero.Crops are ruined. The sun won"t be seen again for
many years. Wars break out as countries fight for food. A year later, no more than 10
million people remain alive.
Could it really happen? In fact, it has already happened more than once in the history
of the Earth. The dinosaurs were on the Earth for over 160 million years. Then 65 million
years ago they suddenly disappeared. Many scientists believe that the Earth was hit by
a piece of object in space. The dinosaurs couldn"t live through the cold climate that
followed and died out. Will we meet the same end?
B. An event of imagination.
C. A research on space.
D. A scientific adventure.
B. damages to cities
C. an Earth explosion
D. huge waves
B. Because the light and heat from the sun can not reach the earth.
C. Because people there can not live at the temperature of zero.
D. Because wars break out among countries.
B.what happened 65 million years ago was an invented story
C. the human beings will die out in 2094
D. the Earth could be hit by other objects in space
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.
- 1解不等式(组)并把解集在数轴上表示出来(每题4分,共16分) (1)5(x+2)≥1-2(x-1)
- 23位同学设计了下列3个实验方案以验证某无色气体中既含有SO2,又含有CO2。方案1:将无色气体通入酸性KMnO4溶液,K
- 3化简:x2x-y-y2x-y.
- 4为了解我市市区及周边近170万人的出行情况,科学规划轨道交通,2010年5月,400名调查者走入1万户家庭,发放3万份问
- 5根据语境,填入适当的词语或句子,补全对话。A: Excuse me, sir? Where is the nearest
- 6阅读下面这首诗,完成下面各题。(6分)度大庾岭①(清)朱彝尊雄关直上岭云孤,驿路梅花岁月徂②。丞相祠堂虚寂寞,越王城阙总
- 7下列有机化合物分子中所有的原子不可能都处于同一平面的是[ ]A.CH3-O-CH3B.HC≡CHC.C6H5-C
- 8下列各句中,标点符号使用正确的一句是[ ]A.东汉班彪说《史记》“辩而不华,质而不俚,文质相称,盖良史之才”,很
- 9函数在处的导数= .
- 10酸奶的口味老少皆宜,是利用下列哪种生物将牛奶经过发酵而成的( )A.酵母菌B.病毒C.乳酸菌D.醋酸杆菌
- 1人们常说:“眼观六路,耳听八方”,这说明眼和耳都是人认识世界的感觉器官。下列有着叙述错误的是A.近视眼可配戴凹透镜加以矫
- 22007年12月22日,沉睡在海底800余年的南宋时古沉船“南海一号”被成功打捞,谱写了我国考古工作的新篇章。下列叙述中
- 3如图所示,固定在竖直平面内倾角为θ=37°的直轨道AB,与倾角可调的足够长的直轨道BC顺滑连接.现将一质量m=0.1kg
- 4材料一 2001年日本前首相小泉坚持参拜供奉有甲级战犯的靖国神社,引起东亚国家强烈愤慨和严厉谴责,中日关系跌至1972
- 5下列反应中,调节反应物用量或浓度不会改变反应产物的是( )A.CO2通入澄清石灰水中B.Na2CO3溶液中滴入HCl溶
- 6一个国家或地区的环境人口容量,是在可预见到的时期内,利用本地资源及其他资源、知识和技术条件,在保证符合其社会文化准则的物
- 7在括号内给划线字注音,根据拼音在括号中工整地写出汉字。 读书时不可存心诘难( )作者,不可尽信书上所言,亦不可
- 8请阅读下图,回答1~2题。1.我国南水北调的主要目的是 [ ]A.解决长江流域的洪涝问题B.连通长江、淮河、黄河
- 9某环保小组监测到一湿法冶铜厂排放的废水中含有硫酸和硫酸铜两种污染物,为测定该废水中各污染物的含量,给冶铜厂提供处理废水的
- 10下列排列顺序正确的是①热稳定性:H2O>HF>H2S ②还原性:HI>HBr>HCl③熔沸点