题目内容
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How does a maglev operate？
A．It uses nuclear energy.
B．It rests on a cushion of pressurized air.
C．It flies over magnetically activated tracks.
D．It uses a device similar to a jet engine.
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How does a Maglev operate？
A．It uses new energy.
B．It rests on a cushion of pressurized air.
C．It flies over magnetically activated tracks.
D．It uses a device similar to a jet engine.
What does the anther imply by writing the last sentence of the passage？
A．Knowing how to operate a motor-car or washing-machine means a high mental intelligence.
B．The technical achievement of Europeans are because of their intelligence.
C．Only knowing how to operate some modem household appliances does not really mean that they are of real intelligence.
D．Europeans are more intelligent than Africans or Asians because they are of mental superiority.
听力原文： What does maglev look like？ Japanese engineers designed a vehicle that runs in a cradle-like track or guideway. Magnetic attraction and repulsion pull and push maglev forward. To stop the trains, the magnetic force is reversed, much like airplanes are stopped by reversing the force of the engines. Both types of maglev are quiet, fast, and save. Since maglev rides on air, there is no friction between wheels and rails to make noise or to slow it down. If the external power fails, there is a battery-operated system on the train itself that takes over and brings the cars to a smooth stop.
Maglev could be the answer to our problems. It could become the typical short and middle-distance mass transportation system of the twenty-first century. If it does, we will enjoy many benefits. We will ride in save, fast, quiet trains between cities up to about 500 miles apart in less time than it takes to fly if you include the time for ground transportation. We will conserve precious land because maglev can be built where railroads run, down the middle of existing super-highways or elevated above existing streets and roads. And we will probably save money, too. According to a German estimate, a mile of two-way track will cost about nine million dollars whereas a mile of interstate highway costs about 25 million dollars in the United States.
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A．Because it is designed like a cradle.
B．Because it is pulled and pushed by magnetic attraction and repulsion.
C．Because it runs on air.
D．Because there's no friction between wheels and rails.
Maglev Trains
If you've been to an airport lately, you've probably noticed that air travel is becoming more and more congested. Despite frequent delays, airplanes still provide the fastest way to travel hundreds or thousands of miles. Passenger air travel revolutionized the transportation industry in the last century, letting people traverse great distances in a matter of hours instead of days or weeks.
The only alternatives to airplanes—feet, ears, buses, boats and conventional trains—are just too slow for today's fast-paced society. However, there is a new form. of transportation that could revolutionize transportation of the 21st century the way airplanes did in the 20th century.
A few countries are using powerful electromagnets to develop high-speed trains, called maglev trains. Maglev is short for magnetic levitation, which means that these trains will float over a guideway using the basic principles of magnets to replace the old steel wheel and track trains. In this article, you will learn how electromagnetic propulsion(电磁推进) works, how three specific types of maglev trains work and where you can ride one of these trains.
Electromagnetic Suspension(EMS)
If you've ever played with magnets, you know that opposite poles attract and like poles repel each other. This is the basic principle behind electromagnetic propulsion. Electromagnets are similar to other magnets in that they attract metal objects, but the magnetic pull is temporary. As you can read about in How Electromagnets Work, you can easily create a small electromagnet yourself by connecting the ends of a copper wire to the positive and negative ends of an AA, C or D-cell battery. This creates a small magnetic field. If you disconnect either end of the wire from the battery, the magnetic field is taken away.
The magnetic field created in this wire-and-battery experiment is the simple idea behind a maglev train rail system. There are three components to this system:
- A large electrical power source
- Metal coils lining a guideway or track
- Large guidance magnets attached to the underside of the train
The big difference between a maglev train and a conventional train is that maglev trains do not have an engine—at least not the kind of engine used to pull typical train cars along steel tracks. The engine for maglev trains is rather unnoticeable. Instead of using fossil fuels, the magnetic field created by the electrified coils in the guideway walls and the track combine to propel the train.
Maglev trains float on a cushion of air, eliminating friction. This lack of friction and the trains' aerodynamic(空气动力学的) designs allow these trains to reach unprecedented ground transportation speeds of more than 310 mph(500 kph), or twice as fast as Amtrak's fastest commuter train. In comparison, a Boeing-777 commercial airplane used for long-range flights can reach a top speed of about 562 mph (905 kph). Developers say that maglev trains will eventually link cities that are up to 1,000 miles (1,609 kin) apart. At 310 mph, you could travel from Paris to Rome in just over two hours.
Electrodynamic Suspension (EDS)
Japanese engineers are developing a competing version of maglev trains that use an electro- dynamic suspension (EDS) system, which is based on the repelling force of magnets. The key difference between Japanese and German maglev trains is that the Japanese trains use super-cooled, superconducting electromagnets. This kind of electromagnet can conduct electricity even after the power supply has been shut off. In the EMS system, which uses standard electromagnets, the coils only conduct electricity when a power supply is present. By chilling the coils at frigid temperatures, Japan's system saves energy. However, the cryogenic(低温学的) system used to cool the coils can be expensive.
Another di
A．Y
B．N
C．NG
High speed trains may be an answer. One fairly new proposal for such trains is for some- thing called a Maglev, meaning a magnetically levitated train. Maglev will not actually ride on the tracks, but will fly above tracks that are magnetically activated. This will save wear and tear on the tracks. These trains will be able to go faster than 150 miles per hour. At this speed, conventional trains have trouble staying on the tracks.
As you can see, Maglev offers exciting possibilities for the future.
What is the main topic of the talk？
A．Energy conversation.
B．Transportation of the future.
C．Transportation problem.
D．Advantages of air transportation over railroad.
A tourist is prevented from entering a country if he does not have ______ passport.
A．an operative
B．a valid
C．an efficient
D．an effective
Why does the woman suggest that the man change his reservation date？
A．The hotel doesn"t open that day.
B．She doesn"t work that day.
C．There is no free room that day.
D．The hotel is fully booked on June 28th.
Why does Bill Randel say that the findings are surprising？
A．The findings are completely opposite to previous findings.
B．The findings are not understandable at all.
C．Water vapor has both positive and negative effects.
D．The effect of water vapor is so significant.
听力原文：M: Hello, this is room 205. What time is dinner, please？
W: The main restaurant opens at 7 in the evening and closes at 10. Our coffee shop is open 24 hours a day.
M: And what time is it now, please？
W: It's6 p.m.
M: Thank you.
Where does the dialogue take place.'？
A．In a hotel.
B．In a store.
C．In a restaurant.
What is the main topic of the passage？
A．Energy conservation.
B．Transportation of the future.
C．Strip cities.
D．Advantages of air transportation over railroads.
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