2008-04-20 00:42:09 作者:成都教育网 来源: 互联网
owflakes
You've probably heard that no two owflakes are alike. Of course, nobody has ever confirmed that statement by examining every one of the estimated one septillion owflakes that drift to Earth each year. still, Ke eth Li recht, a profe or at the California I titute of Technology, is confident that the statement is true.
owflakes aren't flaky, says Li recht. At their basic level, they're crystalline. The lattice of every owflake is six-sided in shape. The simplest ow crystals are six-sided flat plates and six-sided colum . Such crystals are common in places where the air is extremely cold and dry. ow crystals acquire their ecial beauty when their simple six-sided symmetry blo oms. Under the right conditio , each of the six corners of a crystal routs what is called an arm. In a matter of minutes, the arms can become highly ornate and give the crystal a star like a earance.
Several factors in the environment affect the shape and growth rate of a ow crystal. One factor is humidity. Crystals grow faster and in more intricate shape as humidity increases. A second factor is air temperature. A owflake is born when several molecules of water vapor in a could land on a eck of dust and freeze to form a simple crystal. As the young crystal bo around in the cloud, it pa es through air pockets of varying temperatures. If the crystal pa es through a pocket of air that is, says,—15 degrees Celsius, it will grow quickly and rout six arms, says Li recht. If the crystal is then to ed into a warmer pocket, one about-10℃, the arms' ti will stop growing quickly and form six-side plates. If the crystal then drifts into an even warmer pocket of about -℃, its top and bottom will grow more quickly than its sides and become more column like in shape.
In the course of its life an, a ow-crystal might flutter through many warmer and colder pockets, acquiring a complicated and unique growth history. Such a history will give rise to a owflake that is unlike any other. Each arm on the owflake will look exactly like every other one, but the crystal itself will be one of a kind.
Using his cooling tanks, Li recht has learned how to create ow crystals of different shapes—plates, colhu , needles etc. Li recht has even refined his techniques so that he can make crystals that look highly similar to one another. Still, he lacks the control to manufacture identical twin owflakes. A slight difference in humidity and temperature can u et the growth profile of a crystal.
1. What does Profe or Li recht believe to be true?
A. No two owflakes are exactly the same in shape.
B. Somebody has examined all the owflakes that on Earth.
C. The statement that no two owflakes are alike is confirmed.
D. None of the above.
2. What do the simplest ow crystals look like?
A. They have six colum .
B. They are flaky.
C. They are cubic in shape.
D. They are six-sided.
3. What are the factors that affect the shape and growth rate of a ow crystal?
A. Humidity and temperature.
B. Water and falling eed.
C. Air and altitude.
D. Both B and C.
4. It can be felt from the description in the 2nd paragraph that the author
A. admires the beauty of the owflakes.
B. dislikes the changing growth history of the owflakes.
C. has a particular feeling for those flower-like crystals.
D. likes to compare owflakes to the stars in the sky.
5. Li recht is not able to
A. create ow crystals of different shapes.
B. make crystals that look similar to one another.
C. create owflakes that are exactly alike.
D. refine his techniques.
Powering a City? It's a Breeze
The graceful wooden windmills that have broken up the flat Dutch landscape for centuries—a national symbol like wooden shoes and tuli —yielded long ago to ungainly metal-pole turbines.
Now, windmills are breaking into a new frontier. Though still in its teething stages, the “urban turbine” is a high-tech windmill designed to generate energy from the roofto of busy citles. Lighter, quieter, and often more efficient than rural counterparts, they take advantage of the extreme turbulence and rapid shifts in direction that characterize urban wind patter .
Prototypes have been succe fully tested in several Dutch cities, and the city government in the Hague has recently agreed to begin a large-scale deployment in 2003. Current models cost US$8,000 to US$12,000 and can generate between 3,000 and 7,000 kilowatt hours of electricity per year. a typical Dutch household uses 3,500 kilowatt hours per year, while in the United States, this figure jum to around 10,000 kilowatt hours.
But so far, they are being designed more for public or commercial buildings than for private homes. The smallest of the current models weigh roughly 200 kilograms and can be i talled on a roof in a few hours without using a crane.
Germany, Finland and Denmark have also been experimenting with the technology, but the ever-practical Dutch are natural pioneers in urban wind power mainly because of the lack of ace. The Netherlands, with 16 million people crowded into a country twice the size of Slovenia, is the most de ely populated in Europe.
Problems remain, however, for example, public safety concer , and so strict standards should be a lied to any potential manufacturers. Vibratio are the main problem in skyscraper-high turbine. People don't know what it would be like to work there, in an office next to one of the big turbines. It might be too hectic.
Meanwhile, projects are under way to use minimills to generate power for lifeboats, streetlights, and portable generators. “I think the thing about wind power is that you can use it in a whole range of situatio ,” said Corin Millais, of the European Wind Energy A ociation. “It's a very local technology, and you can use it right in you backyard. I don't think anybody wants a nuclear power plant in their backyard.”
1. What are the symbols of Netherlands according to the first paragraph?
A. The flat landscape.
B. Wooden shoes and wooden windmills.
C. Metal-pole turbines.
D. Both A and B.
2. Which statement is best describes the urban turbine mentioned in the second paragraph?
A. It is a windmill put on roofto of buildings for energy generation.
B. It is a high-tech machine designed to generate energy for urban people.
C. It is light and quiet and therefore more efficient.
D. It is driven by urban wind.
3. The smallest models of an urban turbine
A. is designed for private homes.
B. weighs 2,000 kilograms.
C. can be carried up to the rooftop without a crane.
D. can be i talled with a crane.
4. The Netherlands leads in the urban turbine technology because
A. the Dutch are natural pioneers.
B. the Dutch have a tradition with windmills.
C. Netherlands is windier than Germany, Finland and Slovenia.
D. Netherlands is a small country with a large population.
5. According to the last paragraph, what are the advantages of wind power technology?
A. It can be used for different purposes.
B. It can replace nuclear power plant.
C. It can be in stalled in one's backyard.
D. It can be i talled in one's backyard.
Thirsty in Karachi
After two weeks in Karachi, I'm not sure whether to laugh or to cry. Either way, it involves water—or rather the lack of it.
In Western Europe or the US, you only have to turn on the tap and you'll see a jet of cold water, ready to drink, cook and bathe in, or wash the car. Turn on the tap in Karachi and you'll be lucky to fill a few buckets. Until 1947 the city was part of British India, whose engineers built and maintained a modest water su ly network for the city's 500,000 inhabitants. Today, Karachi is home to around 12 million people. Half of them live in slum tow hi , with little or no water through the mai . Even the rich half usually have to wait days before anything tickles through their pipes. And the coloured liquid that finally emerges is usually too contaminated to drink.
Half usually have to wait days before anything tickles through their pipes. And the coloured liquid that finally emerges is usually too contaminated to drink.
According to the state-owned Karachi Water and Sewerage Board, the city needs more than 2,500 million litres of water each day. The board currently su lies 1,650 million litres of which nearly 40 per cent is lost from leaks—and theft. Leaks are dime a dozen to water utilities the world over, but theft?
Karachi's unlikely water pirates turn out to be ordinary families struggling to get adequate su lies of one of life's nece ities. Stealing water takes many forms. The simplest is to buy a suction pump and get it attached to the water pipe that feeds your house from the mai . This should maximize your share of water every time the board switches on the su ly. When the practice started 20 years ago, the pum would be carefully hidden or disguised as garden ornaments. These days people hardly bother. The pum are so wide read and water board i ectors so thin on the ground that when officials do confiscate a pump its owner simply buy a replacement.
I isting that people obey the law won't work because most households have little alternative but to steal. For its part, the Karachi Water and Sewerage Board says it would dearly like to make life easier, but finds itself mired in debt because most residents either won't pay water charges or can't afford to the Urban Resource Centre, a Karachi-based think tank, of the 1.2 million known co umers of water only 750,000 are billed, of whom just 163,000 actually pay for their su lies. The board makes a perpetual lo , and there is no money to improve the system or even plug the leaks. Worse, the board increasingly relies on international loa from i titutio such as the Asian Development Bank, which only makes its debt worse.
The joke is that the owners of the suction pum end up with little—if any—extra water. Your house is in a line with 20 other households all ta ing into one horizontal pipeline. All you can end up doing, given you have pum of equal strength, is redistribute each other's entitlement and pay higher electricity bills into the bargain.
Back home in London, I'll remember not to complain about the water meter, or the hosepipe ban.
1.According to the pa age, people in Karachi today suffer from a short su ly of water because
A. the water su ly network built in 1947 has sto ed to function.
B. the city has become much larger than before.
C. old networks can not meet the need of the city's greatly-increased population.
D. other city is longer a part of British India.
2. Now people in Karachi do not hide or disguise the suction pum they use to steal water because
A. the pum are no longer wanted as garden ornaments.
B. water su ly board officials no longer confiscate them.
C. it does not cost much money to buy a new one.
D. many households have them and there are very few i ectors around to try to find them.
3. Confronted with a severe shortage of water su ly, the city's Water and Sewerage Board
A. tries to improve the water su ly system with borrowed money.
B. is not making any effort to improve the situation.
C. urges the co umers to obey the law.
D. charges the co umers more for the water they use.
4.Which of the following is true of the owners of the suction pum , if their neighbors have equally powerful pum as they do?
A. They get some extra water.
B. They only pay more for electricity.
C. They share what they can get with their neighbors.
D. They replace their pum with new ones.
5. Which of the following is true about the author when he is back home in London?
A. He mi es the days he ent in Karachi.
B. He forgets the complaints he made in Karachi.
C. He is content with the water su ly in London.
D. he complai about the water su ly in London.
在百度搜索:2008年职称英语阅读理解习题(1)