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Thirst for Oil
Worldwide every day,we devour the energy equivalent of about 200 million barrels of oil. Most of the energy on Earth comes from the Sun. In fact enough energy from the Sun hits the planet's surface each minute to cover our needs for an entire year,we just need to find an efficient way to use it. So far the energy in oil has been cheaper and easier to get at. But as supplies dwindle,this will change,and we will need to cure our addiction to oil.
Burning wood satisfied most energy needs until the steam-driven industrial revolution,when energy-dense coal became the fuel of choice. Coal is still used,mostly in power sta-tions,to cover one quarter of our energy needs,but its use has been declining since we star-ted pumping up oil. Coal is the least efficient,unhealthiest and most environmentally dama-ging fossil fuel,but could make a comeback,as supplies are still plentiful:its reserves are five times larger than oil's.
Today petroleum,a mineral oil obtained from below the surface of the Earth and used to produce petrol,diesel oil and various other chemical substances,provides around 40% of the world's energy needs,mostly fuelling automobiles. The US consumes a quarter of all oil,and generates a similar proportion of greenhouse gas emissions.
The majority of oil comes from the Middle East,which has half of known reserves. But other significant sources include Russia,North America,Norway,Venezuela and the North Sea. Alaska's Arctic National Wildlife Refuge could be a major new US source,to reduce reliance on foreign imports.
Most experts predict we will exhaust easily accessible reserves within 50 years,though opinions and estimates vary. We could fast reach an energy crisis in the next few decades, when demand exceeds supply. As conventional reserves become more difficult to access,oth-ers such as oil shales and tar sands may be used instead. Petrol could also be obtained from coal.
Since we started using fossil fuels,we have released 400 billion tonnes of carbon,and burning the entire reserves could eventually raise world temperatures by 13℃ .Among other horrors,this would result in the destruction of all rainforests and the melting of all
Arctic ice.
What do experts say about the earth's fuel reserves?
A: The earth's fuel reserves will be accessible for the next 50 years.
B: There will soon be an energy crisis.
C: Conventional reserves will soon become inaccessible.
D: Fuel demand will decline.
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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 1 997 , 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.
The last paragraph tells us,among other things,that_______.
A: the lidar detector needs improvement
B: many airlines are interested in the system
C: passengers often forget to fasten their seatbelts
D: the lidar detector can be used in a wide range of areas
共用题干
Less Is More
It sounds all wrong—drilling holes in a piece of wood to make it more resistant to knocks. But it works because the energy from the blow gets distributed throughout the wood rather than fo-
cusing on one weak spot. The discovery should lead to more effective and lighter packaging mate-rials.
Carpenters have known______(51)centuries that some woods are tougher than others. Hickory,for example,was turned into axe handles and cartwheel spokes because it can absorb shocks without breaking. White oak,for example,is much more easily damaued,________(52)it is almostas dense.Julian Vincent at Bathe University and his team were convinced the wood's internal structure could explain the differences.
Many trees have tubular vessels that run_______(53)the trunk and carry water to the leav- es .In oak they are large,and arranged in narrow bands,but in hickory they are smaller,and more evenly distributed.The researchers________(54)this layout might distribute a blow's en-ergy throughout the wood, soaking up a bigger hit.To test the idea,they drilled holes 0.65 millimetres across into a block of spruce,a wood with_______(55)vessels,and found that_______(56)withstood a harder knock_______（57)when there were more than about 30 holes per square centimeter did the wood's performance drop off.
A uniform substance doesn't cope well with knocks because only a small proportion of the material is actually______( 58).All the energy from the blow goes towards breaking the material in one or two places , but often the pieces left _________( 59 ) are pristine（未经破坏的）.
But instead of the energy being concentrated in one place,the holes provide many weak spots that all absorb energy as they break,says Vincent.“You are controlling the places______(60) the wood breaks,and it can then absorb more______(61),more safely.”
The researchers believe the principle could be applied to any material—_________(62)example,to manufacture lighter and more protective packaging.It could_______(63)be used in car bumpers,crash barriers and armor for military vehicles,says Ulrike Wegst,_______(64) the Max Plank Institute for Mental Research in Stuttgart. But she emphasizes that you'd ________(65)to design the substance with the direction of force in mind.“The direction of loading is crucial,”she says.
53._________
A: down
B:.over
C: up
D:.into
Flash plants produce hot water through _____.
A.the energy to turn a turbine
B.impermeable rock
C.one or two separators
D.turbine operator
E.little or no water
F.hot springs
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Cloning（克隆）:Future Perlect?
1 A clone is an exact copy of a plant or animal produced from any one cell.Since Scottish
scientists reported that they had managed to clone a sheep named Dolly in 1997,research
into cloning has grown rapidly.In May 1998,scientists in Massachusetts managed to
create two identical calves（牛犊）using cloning technology. A mouse has also been
cloned successfully.But the debate over cloning humans really started when Chicago
physicist Richard Seed made a surprising announcement:"We will have managed to clone
a human being within the next two years."he told the world.
2 Seed's announcement provoked a lot of media attention,most of it negative,In Europe,
nineteen nations have already signed an agreement banning human cloning and in the
U.S. the President announced:"We will be introducing a law to ban all human cloning and
many states in the U. S. will have passed anti-cloning laws by the end of the year."
3 Many researchers are not so negative about cloning.They are worried that laws banning
human cloning will threaten important research.In March,The New England Journal of
Medicine called any plan to ban research on cloning humans seriously mistaken.Many
researchers also believe that in spite of attempts to ban it,human cloning will have become
routine by 2010 because it is impossible to stop the progress of science.
4 Is there reason to fear that cloning will lead to a nightmare world?The public has been
bombarded（轰炸）with newspaper articles, television shows and films, as well as
cartoons.Such information is often misleading,and makes people wonder what on earth
the scientists will be doing next.
5 Within the next five to ten years scientists will probably have found a way of cloning
humans.It could be that pretty soon we will be able to choose the person that we want our
child to look like,But how would it feel to be a clone among hundreds,the anti-cloners
ask. Pretty cool, answer the pro-cloners（赞成克隆的人）.
Richard Seed claimed to be able to clone_______.
A:the nucleus of a cell
B:cloned human beings
C:a human being in two years
D:a law to ban human cloning
E:a report on human cloning
F:heavy media coverage
