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第三篇
The Exploding Lakes of Cameroon
What comes to mind when you think of a lake?You probably imagine a pretty scene
with blue water,birds,and fish.For the people in the northwestern Cameroon,however,
the image is very different.For them,lakes may mean terrible disasters.In 1984,
poisonous gases exploded out of Lake Monoun and came down into the nearby villages,
killing thirty-seven people.Two years later,Lake Nyos erupted.A cloud of gases rolled
down the hills and into the valleys and killed 1,700 people.
Lake Nyos and Lake Monoun are crater(火山口)lakes. They were formed when
water collected in the craters of old volcanoes.The volcanoes under Lake Nyos and Lake
Monoun are not active anymore.However,poisonous gases from the center of the earth
continue to flow up through cracks in the bottom of the lake.This is normal in a crater lake.
In most crater lakes,these gases are released often because the water"turns over"
regularly.That is,the water from the bottom of the lake rises and mixes with the water at
the top,allowing the gases to escape slowly.
However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows
the reason for this fact,but as a result,these lakes have more gases trapped at the bottom
than other crater lakes.In fact,scientists who have studied Lakes Nyos and Monoun have
found 16,000 times more gases.When a strong wind,cool weather,a storm,or a
landslide(滑坡)causes the water to turn over suddenly,the gases escape in a violent
explosion.
In the past,no one knew when the gases might explode,so there was no way for the
villagers to escape disaster. Now scientists from the United States,France,and
Cameroon have found a way to reduce the gas pressure at the bottom of Lake Nyos.They
stood a 672-foot plastic pipe in the middle of the lake,with one end of the pipe near the
bottom and the other end in the air. Near the top of the pipe,the team put several holes
that could be opened or closed by a computer.Now,when the gas pressure gets too high,
the holes are opened and some of the gas-filled water shoots up through the pipe into the air
like a fountain.With less pressure,a disastrous explosion is much less likely.However,
the scientists are not sure that one pipe will be enough to prevent explosions.They hope to
put in others soon and they plan to install a similar pipe and a computer system at Lake
Monoun as well.
To protect people nearby until all of the pipes are in place,the scientists have installed
early warning systems at both lakes.If the gas pressure rises to a dangerous level,
computers will set off loud sirens(警报)and bright lights to warn the people in the villages.
That way,they will have time to escape from the dangerous gases.
Which of the following statements about Lake Nyos and Lake Monoun is true?
A:They were formed in 1984.
B:They are at the top of two active volcanoes.
C:They are not like most other crater lakes.
D:Water in them turns over regularly.
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Improve Your Memory
To many people advancing age means losing your hair,your waistline and your memory.But is it an inescapable fact that the older you get,the less you remember? Well,as time goes by,we tend to blame age for problems that are not necessarily age-related.
When a teenager can't find her keys,she thinks it's because she's distracted or disorganized, but a 70-year-old blames her memory. In fact,the 70-year-old may have been misplacing things for decades一like we all do from time to time.
In healthy people,memory doesn't deteriorate as quickly as many of us think. According to psychologists,as we age,our memory mechanism isn't broken,it's just different.The brain's processing time slows down over the years,though no one knows exactly why.Recent research suggests that nerve cells lose efficiency and that there's less activity in the part of the brain that decides whether to store information or not.But it's not clear that less activity is worse.A beginning athlete is winded. more easily than a trained athlete.In the same way,as the brain gets more skilled at a task,it spends less energy on it.
There are steps you can take to improve your memory,though you have to work to keep your brain in shape.It's like having a good body. You can't go to the gym once a year and expect to stay in top form.
Some memory enhancement experts suggest using the AM principle.Pay attention to what you want to remember. Then give some meaning to it. We remember things when we focus on them, whether we intend to or not. That helps explain why jingles stick in our minds.They are played on loud,flashy TV commercials.They also use rhyme and music to help us remember better.
Basic organization helps us remember the boring stuff. For example,rather than trying to recall a random list of groceries,we can divide them into categories,such as dairy,meat and produce. For important things like keys and money,we can set up a"forget-me-not"spot where we always keep them.
We can also eat to aid our memory power. Whole grains,fruits and vegetables are excellent sources of glucose,the brain's preferred fuel. Another low-tech way to improve memory is to get adequate rest. Sleep may allow our brain time to encode memories.
Interest in friends,family and hobbies does wonders for our memory.A sense of passion or purpose helps us remember. Memory requires us to pay attention to our lives,allowing us to discover in them everything worth remembering.
In the AM principle,the letters A and M most likely refer to attention and memory respectively.
A:Right
B:Wrong
C:Not mentioned
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The Greatest Mystery Of Whales
The whale is a warm-blooded,air-breathing animal,giving birth to its young alive,
sucking them一and,like all mammals,originated on land.There are many_________
(1)of this. Its front flippers(鳍状肢),used for steering and stability,are traces of feet.
Immense strength is_________(2)into the great body of the big whales,and in
fact most of a whale's body is one gigantic muscle.The blue whale's pulling strength has
been estimated_________(3)400 horsepower. One specimen was reported to have
towed(拖)a whaling vessel for seven hours at the_________(4)of eight knots (节).
An angry whale will_________(5)a ship.Afamous example of this was the fate
of whaler Essex,_________(6)was sunk off the coast of South America early in the
last century. More recently,steel ships have_________(7) their plates buckled(使弯
曲)in the same way. Sperm whales(抹香鲸)were known to seize the old-time
whaleboats in their jaws and crush them.
The greatest_________(8)of whales is their diving ability.The sperm whale dives
to the bottom for his_________(9) food, the octopus(章鱼).In that search he is
known to go as far down as 3, 200 feet,where the_________(10)is 1,400 pounds,to
a square inch.Doing so he will_________(11)underwater long as one hour. Two
special skills are involved in this:storing up enough_________(12)(all whales are air-
breathed)and tolerating the great change in pressure.Just how he does it scientists have
not_________(13).It is believed that some of the oxygen is stored in a special
_________(14)of blood vessels,rather than just held in the lungs.And it is believed
that a special kind of oil in his head is some sort of compensating mechanism that
_________(15)adjusts the internal pressure of his body.But since you can't bring a
live whale into the laboratory for study,no one knows just how these things work.
_________(13)
A:witnessed
B:determined
C:applied
D:calculated
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Green Energy
1.Green energy is energy that is produced in a manner that has, less of a negative impact to the environment than energy sources like fossil fuels,which are often produced with harmful side effects."Greener" types of energy that often come to mind are solar,wind,geothermal and hydro energy.There are several more,even including nuclear energy,that is sometimes considered a green energy source because of its lower waste output relative to energy sources such as coal or oil.
2.The goal of green energy is generally to create power with as little pollution as possible produced as a by-product. Every form of energy collection will result in some pollution,but those that are green are known to cause less than those that are not. Most people who advocate greener sources of energy claim that the result of worldwide use of green energy will result in the ability to preserve the planet for a longer time.Greenhouse gases,a by-product of traditional sources of energy such as fossil fuels are thought to be causing global warming,or the process of the Earth heating up at an accelerated pace.
3.It is not completely necessary for green energy sources to come from places like solar or wind fields,which are examples of green"power plants".A green energy source can be a building that is designed in a way that it keeps itself cool in the daytime and heated in the night through its architectural design rather than having an air-conditioning or a heating system. The conservation of energy through architectural(建筑学的)design becomes, itself, a green energy source. Similarly, many sources of green energy can come directly from the area in which the energy is needed rather than from an outside source.
4.One of the goals of green energy technology is to take existing fossil fuel energy technology and clean it up so it is produced more cleanly. One such case is that of clean coal technology,where scientists are trying to find ways to extract energy from coal and other fossil fuels without all of the harmful side effects.The success of such these types of green energy depend upon the ability to extract harmful by-products from fossil fuels while not only being energy efficient,but by being cost efficient as well.
Greenhouse gases are thought to be causing______.
A:global warming
B:carbon emission
C:lower waste output
D:a green energy source
E:fossil fuels
F: clean fuels
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Climate Change:The Long Reach
1.Earth is warming.Sea levels are rising.There's more carbon in the air,and Arctic ice is melting faster than at any time in recorded history.Scientists who study the environment to better gauge(评估) Earth's future climate now argue that these changes may not reverse for a very long time.
2.People burn fossil fuels like coal and oil for energy.That burning releases carbon dioxide,a colorless gas.In the air,this gas traps heat at Earth's surface.And the more carbon dioxide released,the more the planet warms.If current consumption of fossil fuels doesn't slow,the long-term climate impacts could last thousands of years-and be more severe than scientists had been expecting.Climatologist Richard
Zeebe of the University of Hawaii at Manoa offers this conclusion in a new paper.
3.Most climate-change studies look at what's going to happen in the next century or so.During that time, changes in the planet' s environment could nudge(推动)global warming even higher.For example, snow and ice reflect sunlight back into space.But as these melt,sunlight can now reach-and warm-the exposed ground.This extra heat raises the air temperature even more,causing even more snow to melt.This type of rapid exaggeration of impacts is called a"fast feedback".
4.Zeebe says it's important to look at fast feedbacks.However,he adds,they're limited.From a climate change perspective,"This century is the most important time for the next few generations,"he told Science News."But the world is not ending in 2100."For this new study,Zeebe now focuses on"slow feedbacks".While fast feedback events unfold over decades or centuries,slow feedbacks can take thousands of years.Melting of continental ice sheets and the migration of plant life-as they relocate to more comfortable areas-are two examples of slow feedbacks.
5.Zeebe gathered information from previously published studies investigating how such processes played out over thousands of years during past dramatic changes in climate.Then he came up with a forecast for the future that accounts for both slow and fast feedback processes.Climate forecasts that use only fast feedbacks predict a 4.5 degree Celsius(8.1 degree Fahrenheit)change by the year 3000.But slow feedbacks added another 1.5℃-for a 6℃ total increase,Zeebe reports.He also found that slow feedback events will cause global warming to persist for thousands of years after people run out of fossil fuels to burn.
Arctic ice has never been melting so fast in______.
A:the exposed ground
B:a very long time
C:the extra heat
D:recorded history
E:previously published studies
F:rapid exaggeration of impacts
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California Gives Green Light to Space Solar Power
Energy beamed down from space is one step closer to reality,now that California has given the green
light to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatts(兆瓦)of power
beamed down from solar-power satellites beginning in 2016.But some major challenges will have to be
overcome if the technology is to be used widely.
A start-up company called Solaren is designing the satellites,which it says will use radio waves to beam
energy down to a receiving station on Earth.
The attraction of collecting solar power in space is the almost uninterrupted sunshine available in geo-
synchronous(与地球同步的)orbit. Earth-based solar cells , by contrast , can only collect sun light during day-
time and when skies are clear.
But space-based solar power must grapple(努力克服)with the high cost per kilogram of launching things in-
to space,says Richard Schwartz of Purdue University in West Lafayette,Indiana."if you're talking about it being
economically viable for power of the Earth,it's a tough go,"he says.
Cal Boerman,Solaren's director of energy services,says the company designed its satellites with a view
to keeping launch costs down."We knew we had to come up with a different,revolutionary design,"he says.
A patent the company has won describes ways to reduce the system's weight,including using inflatable mir-
rors to focus sunlight on solar cells,so a smaller number can collect the same amount of energy.
But using mirrors introduces other challenges,including keeping the solar cells from overheating,says
Schwartz."You have to take care of heat dissipation(散发)because you're now concentrating a lot of energy
in one place,"he says.According to the company's patent,Solaren's solar cells will be connected to radia-
tors to help keep them cool.
Though Boerman says the company believes it can make space-based solar power work,it is not expec-
ting to crowd out other forms of renewable energy.Laws in California and other states require increasing use
of renewable energy in coming years,he points out."To meet those needs,we're going to need all types of
renewable energy sources,"he says.
Space-based solar cells could collect solar power only when skies are clear.
A:Right
B:Wrong
C:Not mentioned
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Pathways to Research:Problem-solving
1.Pittsburgh's many hills aren't kind to bikers.Anyone hoping to pedal to work there has to contend with steep streets like Canton Avenue,which famously climbs at a nearly 40-degree angle.As a result,some residents avoid biking altogether.
2.But University of Pittsburgh graduate Micah Toll,23,and a few friends recently launched an invention that they hope will, increase the city's pedal power:An electric bike called a Pulse PEVO.AM super-strong battery powers the bicycle.Able to hit nearly 20 miles per hour without pedaling,it zips up the city' s most daunting(令人却步的)hills.Toll hopes it will persuade people in Pittsburgh and elsewhere to get out of their cars and onto bikes.
3.If it sounds like Toll has a knack(窍门)for fixing problems,that's because he does.In high school,he designed a new type of construction beam.It weighs no more than a feather pillow but can be used to build sturdy(坚固的)homes for refugees fleeing war or natural disaster.For his work , Toll was invited to attend the Intel International Science and Engineering Fair(ISEF)-twice,in 2006 and 2007.The annual competition for young researchers is a program of Society for Science&the Public(that's the parent organization of Science News for Kids).Toll says that when it comes to science,he keeps it simple:"You see a problem and say,‘How could I solve that?’",
4.He's not the only one to take that approach.Many young researchers get their start by trying to solve a problem or fulfill a need in their own communities.When students dedicate themselves to finding a solution that may benefit their community , " a passion is ignited,(点燃),"says Wendy Hawkins , executive director of the Intel Foundation,which sponsors Intel ISEF."Finding that passion and fostering it can be the key to many students'future success."she says.
Paragraph 4______
A:Intel International Science and Engineering Fair
B:The Enthusiasm for Solving Problems
C:The Young Researchers'Passion
D:An Invention Increasing Pedal Power
E:Why People Avoid Biking in Pittsburgh
F:The Cause of National Disaster
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Toads are Arthritic and in Pain
Arthritis(关节炎)is an illness that can cause pain and swelling in your bones. Toads(蟾蜍),a big problem
'in the north of Australia,are suffering from painful arthritis in their legs and backbone,a new stu街has shown.
The toads that jump the fastest are more likely to be larger and to have longer legs.______(46)
The large yellow toads,native to South and Central America,were introduced into the north-eastern Aus-
tralian state of Queensland in 1935 in an attempt to stop beetles and other insects from destroying sugarcane
crops.Now up to 200 million of the poisonous toads exist in the country,and they are rapidly spreading
through the state of Northern Territory at a rate of up to 60 km a year. The toads can now be found across
more than one million square kilometres.________(47)A Venezuelan poison virus was tried in the 1990s
but had to be abandoned after it was found to also kill native frog species.
The toads have severely affected ecosystems in Australia. Ariinials,arid sometimes pets,that eat the toads die im-
mediately from their poison,and the toads themselves eat anything they can fit inside their mouth._________(48)
A co-author of the new study,Rick Shine,a professor at the University of Sydney,says that little atten-
tion has been given to the problems that toads face.Rick and his colleagues studied nearly 500 toads from
Queensland and the Northern Territory and found that those in the latter state were very different.They were
active,sprinting down roads and breeding quickly.
According to the results of the study,the fastest toads travel nearly one kilometre a night._________(49)
But speed and strength come at a price一arthritis of the legs and backbone due to constant pressure placed on
them.
In laboratory tests,the researchers found that after about 15 minutes of hopping,arthritic toads would
travel less distance with each hop(跳跃).________
(50)These toads are so programmed to move,
apparently,that even when in pain the toads travelled as fast and as far as the healthy ones,continuing their
constant march across the landscape.
__________(50)
A:Toads are not built to be road runners一they are built to sit around ponds and wet areas.
B:The task now facing the country is how to remove the toads.
C:Furthermore,they soon take over the natural habitats of Australia's native species.
D:Toads with longer legs move faster and travel longer distances,while the others are being left behind.
E:But this advantage also has a big drawback一up to 10%of the biggest toads suffer from arthritis.
F: But arthritis didn't slow down toads outside the laboratory,the researchers found.
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1. Do you know a child who survived leukemia(白血病)?Do you have a mother , sister or aunt whose breast cancer was found early thanks to a mammogram(乳腺X光照片)?Do you have a friend or coworker who quit smoking to reduce their risk of lung cancer? Each of these individuals benefited from the American Cancer Society's research program.
2.Each day scientists supported by the American Cancer Society work to find breakthroughs that will take US one step closer to a cure.The American Cancer Society has long recognized that research holds the ultimate answers to the prevention,diagnosis and treatment of cancer.
3.As the largest source of nonprofit cancer research funds in the United States,the American Cancer Society devotes over $100 million each year to research.Since 1946,they've invested more than $2. 4 billion in research. The investment has paid rich dividends(回报、效益).In 1946,only one in four cancer patients was alive five years after diagnosis;today 60 percent live longer than five years.
4.Investigators and health professionals in universities,research institutes and hospitals throughout the country receive grants from the American Cancer Society.Of the more than 1,300 new applications received each year,only 11 percent can be funded.If the American Cancer Society had more money available for research funding,nearly 200 more applications considered outstanding could be funded each year.
5.You can help fund more of these applications by participating in the American Cancer Society Relay(接力)for Life,a team event to fight cancer. More funding means more cancer breakthroughs and more lives being saved.To learn more,call Donna Hood,chair with the Neosho Relay for Life of the American Cancer Society at 451-4880.
Many outstanding applications are turned down each year for__________.
A:lack of funding
B:many cancer patients
C:more lives being saved
D:more than five years
E:the ultimate answers
F: more funding
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She could not formulate her ideas in a few words.
A: state
B: argue
C: invent
D: announce
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