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听力原文： Aid workers in Mozambique say they' re increasingly confident that they are coming to terms with the humanitarian crisis that follows the devastating floods. Helicopters and planes have been working flat-out to get supplies through to areas of need. The World Health Organization has warned that malaria has risen sharply after the flooding. This report from Jim Fish in Maputong: "The skies over Mozambique have never been this busy. Relays of helicopters and aircraft crisscross to and fro ferrying food and supplies to the stricken areas. A fleet of more than 50 aircraft are now operating, averaging 200 flights per day. At one forward supply depot in the town of Pamela, helicopters were arriving every few minutes, ferrying sacks of maize, and rice and beans out to where the flood survivors are congregated. But there are still pockets of people who have not received food or fresh water for over a week."
Aid workers in Mozambique say they are confident that______.
A．they are coming to terms with the humanitarian crisis
B．they can get more help from the outside world
C．they can get supplies through to the areas of need
D．they can help themselves
But weight is not the only factor. The smaller the computer the faster it can work. The signals go to and fro at a very high but almost constant speed. So if one can scale down all dimensions to, let us say, one tenth, the average lengths of the current-paths will be reduced to one tenth. So, very roughly speaking, scaling down of all linear dimensions in the ratio of one to ten also gives a valuable bonus: the speed of operation is scaled up 10 times. Other techniques allow even further speed increases.
This increase of operation is a real advantage. There are some applications in which computers could be used which require very fast response times. Many of these are military, of course; but military applications also have applications in engineering sooner or later. For example, automatic blind landing of aircraft requires continuous computer calculations which result in control of the aircraft flight. The more immediate the responses are, the more stable that control can be.
Another advantage is that less power is required to run the computer. In space vehicles and satellites this is an important matter; but even in a trial application we need not waste power. Sometimes a computer takes so much power that cooling systems which require still more power have to be installed to keep the computer from getting too hot, which would increase the risk of faults developing. So a computer which does not need to be cooled saves power on two counts.
Another advantage is reliability. Mini-computers have been made possible by the development of integrated circuits. Instead of soldering bits of wire to join separate components such as resistors and capacitors sometimes in the most intricate networks, designers can now produce many connected circuits in one unit which involves no soldering and therefore no risk of broken joints at all.
Which of the following is NOT one of the advantages of mini-computers？
A．The increase of operation speed.
B．The decrease of power needed.
C．The development integrated circuits.
D．Their reliability.
Flying the Hypert Skies
A little airplane has given new meaning to the term "going hyper. "
The Hyper-X recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound. That's about 5,000 miles per hour. At this speed, you'd get around the world -- flying along the equator (赤道) -- in less than 5 hours.
The Hyper-X is an unmanned,experimental aircraft just 12 feet long. It achieves hypersonic (超音速的) speed using a special sort of engine known as a scramjet. It may sound like something from a comic book,but engineers have been experimenting with scramjets since the 1960s.
For an engine to burn fuel and produce energy, it needs oxygen. A jet engine, like those on passenger airplanes, gets oxygen from the air. A rocket engine typically goes faster but has to carry its own supply of oxygen. A scramjet (紧急刹车) engine goes as fast as a rocket, but it doesn't have to carry its own oxygen supply. A scramjet's special design allows it to obtain oxygen from the air that flows through the engine. And it does so without letting the fast-moving air put out the combustion (燃烧) flames. However, a scramjet engine works properly only at speeds greater than five times the speed of sound. A booster rocket carried the Hyper-X to an altitude of about 100,000 feet for its test flight. The aircraft's record-beating flight lasted just 11 seconds. Although the little plane's self-powered flight lasted only 11 seconds, that brief journey on March 27 makes a major milestone on the way to a new breed of very fast airplanes, comments Werner J. A. Dahm of the University of Michigan in Ann Arbor. In the future, engineers predict, airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Such hypersonic jets could potentially carry passengers anywhere in the world in just a few hours.
Out of the three experimental Hyper-X aircrafts built for NASA, only one is now left. The agency has plans for another 11-second hypersonic flight, this time at 10 times the speed of the sound.
The Hyper-X broke the record because
A．it was the first air-breathing jet plane.
B．it flew along the equator.
C．it flew at speeds smaller than five times the speed of sound.
D．it traveled at a supersonic speed.
SECTION C NEWS BROADCAST
Directions: In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. At the end of each news item, you will be given 10 seconds to answer the questions.
听力原文： A man stole a small aircraft at gunpoint Sunday and flew it over downtown Frankfurt, circling skyscrapers and threatening to crash into the European Central Bank. He landed safely after about two hours and was arrested. The man told the television station he wanted to call attention to Judith Resnik, a US astronaut killed in the 1986, post-lannch explosion of the space shuttle Challenger. Military jets chased the stolen two-seat motorized glider as the man began circling slowly above Frankfurt's banking district. Thousands of people were evacuated from the main railway station, two upper housds and several skyscrapers. Police identified the man as a 31-year-old German student from Darmstadt, a city about 25 miles south of Frankfurt. In radio contact with air traffic controllers, the man threatened to crash into the European Central Bank headquarters unless he was allowed the TV interview as well as a call to Baltimore. He later said he wanted to commit suicide by plunging the plane into the Main River. It was unclear if the man was forced to land or talked down. Air traffic controllers and the police psychologist had been in contact with him.
The man stole the aircraft mainly because he wanted to ______.
A．destroy the European Central Bank.
B．have an interview with a TV station.
C．circle skyscrapers in downtown Frankfurt.
D．remember the death of a US astronaut.
Please Fasten Your Seatbelts
Severe turbulence (湍流) can kill aircraft passengers. Now, in test flights over the Rocky Mountains; NASA (美国航空航天局) engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.
Clear-air turbulence often catches pilots by surprise. Invisible to radar, it is difficult to forecast and can hurl (用力抛出去) passengers about the cabin. In December 1997, one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 metres in a few seconds.
However, passengers can avoid serious injury by fastening their seatbelts. "It is the only antidote (对策) for this sort of thing," says Rod Bogue, project manager at NASA's Dryden Flight Research Center in Edwards, California.
The centre's new turbulence detector is based on lidar, or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect. The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air, the speed equals the plane's airspeed. But as the particles swirl (打漩) in rough air, their speed of approach increases or decreases rapidly. The rate of change in speed corresponds to the severity (激烈程度) of the turbulence.
In a series of tests that began last month, a research jet flew repeatedly. into disturbed air over the mountain ridges (山脉) near Pueblo, Colorado. The lidar detector spotted turbulence between 3 and 8 kilometres ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.
Bogue says that he had "a comfortable amount of time" to fasten his seatbelt. The researchers are planning to improve the lidar's range with a more powerful beam. The system could be installed on commercial aircraft in the next few years.
What does "clear-air turbulence" probably mean？ (Paragraph 1)
A．A not very rough storm.
B．Unexpected disturbed air.
C．A kind of visible storm.
D．A storm over mountain ridges.
Please Fasten Your Seatbelts Severe turbulence (湍流) can kill aircraft passengers. Now, in test flights over the Rocky Mountains, NASA (美国航空航天局) engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.
Clear-air turbulence often catches pilots by surprise. Invisible to radar, it is difficult to forecast and can hurl (用力抛出去) passengers about the cabin. In December 1997, one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 metres in a few seconds.
However, passengers can avoid serious injury by fastening their seatbelts. “It is the only antidote (对策) for this sort of things,” says Rod Bogue, project manager at NASA’s Dryden Flight Research Center in Edwards, California.
The centre’s new turbulence detector is based on lidar, or laser radar, Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect. The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air, the speed equals the plane’s airspeed. But as the particles swirl (打漩) in rough air, their speed of approach increases or decreases rapidly. The rate of change in speed corresponds to the severity (激烈程度) of the turbulence.
In a series of tests that began last month, a research jet flew repeatedly into disturbed air over the mountain ridges (山脉) near Pueblo, Colorado. The lidar detector spotted turbulence between 3 and 8 kilometres ahead, and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.
Bogue says that he had “ a comfortable amount of time” to fasten his seatbelt. The researchers are planning to improve the lidar’s range with a more powerful beam. The system could be installed on commercial aircraft in the next few years.
第6题：What does “clear-air turbulence” probably mean？ （Paragraph 1）
A．A not very rough storm.
B．Unexpected disturbed air.
C．A kind of visible storm.
D．A storm over mountain ridges.
根据下列材料，请回答题
Please Fasten Your Seatbelts
Severe turbulence （潮流 can kill aircraft passengers. Now， in test flights over the Rocky Mountains， NASA （美国航空航天局）engineers have successfully detected clear-air turbulence up to 10 seconds before an aircraft hits it.
Clear-air turbulence often catches pilots by surprise. Invisible to radar， it is difficult to fore- cast and can hurl （用力抛出去） passengers about the cabin. In December 1997， one passenger died and a hundred others were injured when unexpected rough air caused a United Airlines flight over the Pacific to drop 300 meters in a few seconds.
However， passengers can avoid serious injury by fastening their seatbelts. "It is the only antidote （对策）for this sort of thing，" says Rod Bogue， project manager at NASA"s Dryden Flight Research Center in Edwards， California. The centre"s new turbulence detector is based on lidar， or laser radar. Laser pulses are sent ahead of the plane and these are then reflected back by particles in the air. The technique depends on the Doppler effect. The wavelength of the light shifts according to the speed at which the particles are approaching. In calm air， the speed equals the plane"s airspeed. But as the particles swirl （打漩） in rough air， their speed of approach increases or decreases rapidly. The rate of change in speed corresponds to the severity （激烈程度）of the turbulence.
In a series of tests that began last month， a research jet flew repeatedly into disturbed air over the mountain ridges （山脉） near Pueblo， Colorado. The lidar detector spotted turbulence between 3 and 8 kilometers ahead， and its forecasts of strength and duration corresponded closely with the turbulence that the plane encountered.
Bogue says that he had "a comfortable amount of time" to fasten his seatbelt. The researchers are planning to improve the lidar"s range with a more powerful beam. The system could be installed on commercial aircraft in the next few years.
What does "clear-air turbulence" in Paragraph 1 probably mean？ 查看材料
A.A not very rough storm.
B.Unexpected disturbed air.
C.A kind of visible storm.
D.A storm over mountain ridges.
Part B
Copying Birds May Save Aircraft Fuel
Both Boeing and Airbus have trumpeted the efficiency of their newest aircraft, the 787 and A350 respectively. Their clever designs and lightweight composites certainly make a difference. But a group of researchers at Stanford University, led by Ilan Kroo, has suggested that airlines could take a more naturalistic approach to cutting jet-fuel use, and it would not require them to buy new aircraft.
The answer, says Dr Kroo, lies with birds. Since 1914, scientists have known that birds flying in formation—a V-shape—expend less energy. The air flowing over a bird's wings curls upwards behind the wingtips, a phenomenon known as upwash. Other birds flying in the upwash experience reduced drag, and spend less energy propelling themselves. Peter Lissaman, an aeronautics expert who was formerly at Caltech and the University of Southern California, has suggested that a formation of 25 birds might enjoy a range increase of 71 % .
When applied to aircraft, the principles are not substantially different. Dr Kroo and his team modelled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to assemble over Utah, assume an inverted V-formation, occasionally change places so all could have a turn in the most favourable positions, and proceed to London. They found that the aircraft consumed as much as 15% less fuel (coupled with a reduction in carbon-dioxide output). Nitrogen-oxide emissions during the cruising portions of the flight fell by around a quarter.
There are, of course, knots to be worked out. One consideration is safety, or at least the perception of it. Would passengers feel comfortable travelling in companion？ Dr Kroo points out that the aircraft could be separated by several nautical miles, and would not be in the intimate groupings favoured by display teams like the Red Arrows. A passenger peering out of the window might not even see the other planes. Whether the separation distances involved would satisfy air-traffic-control regulations is another matter, although a working group at the International Civil Aviation Organisation has included the possibility of formation flying in a blueprint for new operational guidelines.
It remains to be seen how weather conditions affect the air flows that make formation flight more efficient. In zones of increased turbulence, the planes' wakes will decay more quickly and the effect will diminish. Dr Kroo says this is one of the areas his team will investigate further. It might also be hard for airlines to co-ordinate the departure times and destinations of passenger aircraft in a way that would allow them to gain from formation flight. Cargo aircraft, in contrast, might be easier to reschedule, as might routine military flights.
As it happens, America's armed forces are on the case already. Earlier this year the country's Defence Advanced Research Projects Agency announced plans to pay Boeing to investigate formation flight, thought the programme has yet to begin. There are reports that some military aircraft flew in formation when they were low on fuel during the Second World War, but Dr Lissaman says they are unsubstantiated. "My father was an RAF pilot and my cousin the skipper of a Lancaster lost over Berlin, "he adds. So he should know.
Findings of the Stanford University researchers will promote the sales of new Boeing and Airbus aircraft.
A．True
B．False
Copying Birds May Save Aircraft Fuel
Both Boeing and Airbus have trumped the efficiency of their newest aircraft, the 787 and A350 respectively. Their clever designs and lightweight composites certainly make a difference. But a group of researchers at Stanford University, led by Ilan Kroo, has suggested that airlines could take a more naturalistic approach to cutting jet-fuel use, and it would not require them to buy new aircraft.
The answer, says Dr Kroo, lies with birds. Since 1914, scientists have known that birds flying in formation-a V-shape-expand less energy. The air flowing over a bird's wings curls upwards behind the wingtips, a phenomenon known as upwash. Other birds flying in the upwash experience reduced drag, and spend less energy propelling themselves. Peter Lissaman, an aeronautics expert who was formerly at Caltech and the University of Southern California, has suggested that a formation of 25 birds might enjoy a range increase of 71%.
When applied to aircraft, the principles are not substantially different. Dr. Kroo and his team modelled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to assemble over Utah, assume an inverted V-formation, occasionally change places so all could have a turn in the most favourable positions, and proceed to London. They found that the aircraft consumed as much as 15% less fuel (coupled with a reduction in carbon-dioxide output). Nitrogen-oxide emissions during the cruising portions of the flight fell by around a quarter.
There are, of course, knots to be worked out. One consideration is safety, or at least the perception of it. Would passengers feel comfortable travelling in companion？ Dr. Kroo points out that the aircraft could be separated by several nautical miles, and would not be in the intimate groupings favoured by display teams like the Red Arrows. A passenger peering out of the window might not even see the other planes. Whether the separation distances involved would satisfy air- traffic-control regulations is another matter, although a working group at the International Civil Aviation Organisation has included the possibility of formation flying in a blueprint for new operational guidelines.
It remains to be seen how weather conditions affect the air flows that make formation flight more efficient. In zones of increased turbulence, the planes' wakes will decay more quickly and the effect will diminish. Dr. Kroo says this is one of the areas his team will investigate further. It might also be hard for airlines to co-ordinate the departure times and destinations of passenger aircraft in a way that would allow them to gain from formation flight. Cargo aircraft, in contrast, might be easier to reschedule, as might routine military flights.
As it happens, America's armed forces are on the case already. Earlier this year the country's Defence Advanced Research Projects Agency announced plans to pay Boeing to investigate formation flight, though the programme has yet to begin. There are reports that some military aircraft flew in formation when they were low on fuel during the Second World War, but Dr. Lissaman says they are unsubstantiated. "My father was an RAF pilot and my cousin the skipper of a Lancaster lost over Berlin," he adds. So he should know.
Findings of the Stanford University researchers will promote the sales of new Boeing and Airbus aircraft.
A．Right
B．Wrong
The Hyper-X
The Hyper-X (超音速飞机) recently broke the record for air-breathing jet planes when it traveled at a Hypersonic speed (超音速) of seven times the speed of sound. That's about 5,000 miles per hour: At this speed, you'd get around the world -flying along the equator (赤道) - in less than 5 hours.
The Hyper-X is an unmanned, experimental aircraft just 12 feet long. It achieves hypersonic speed using a special sort of engine known as a scramjet (超音速冲压式喷气发动机).
For an engine to burn fuel and produce energy, it needs oxygen. A jet engine, like those on passenger airplanes, gets oxygen from the air. A rocket engine typically goes faster but has to carry its own supply of oxygen. A scramjet engine goes as fast as a rocket, but it doesn't have to carry its own oxygen supply.
A scramjet's special design allows it to obtain oxygen from the air that flows through the engine. And it does so without letting the fast-moving air put out the combustion (燃烧) flames. However, a scramjet engine works properly only at speeds greater than five times the speed of sound.
A booster rocket (助推火箭) carried the Hyper-X to an altitude of about 100,000 feet for its test flight. The aircraft's record-beating flight lasted just 11 seconds. That brief journey on March 27 makes a major milestone on the way to a new breed of very fast airplanes, says Werner J. A. Dahm of the University of Michigan in Ann Arbor. In the future, engineers predict, airplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink (边缘) of space. Such hypersonic jets could carry passengers anywhere in the world in just a few hours.
Out of the three experimental Hyper-X aircrafts built for NASA, only one is now left. The agency has plans for another 11-second hypersonic flight, this time at 10 times the speed of sound.
The Hyper-X broke the record because
A．it was the first air-breathing jet plane.
B．it flew along the equator.
C．it traveled at the speed of sound.
D．it reached a speed of about 5,000 miles per hour.
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