阅读理解。 Trees could be more important to the earth"s climatethan previously th
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a new study thatreveals forests help to block out the sun.
Scientists in the UK and Germanyhave discovered that trees release achemical that thickens
clouds abovethem, which reflects more sunlight andcools the earth. The research suggeststhat
chopping down forests could speed
up global warming, and that protecting existing trees couldbe one of the best ways to
deal with the problem.
Dominick Spracklen, of the Institute for Climate andAtmospheric Science at Leeds
University, said, "We thinkthis could have quite a great effect. You can think of forestsas
climate air conditioners. "
The scientists looked at chemicals called terpenes(萜烯) that are released from
northern forests across northernregions such as Canada, Scandinavia and Russia. The
chemicals give forests a special smell, but their function haspuzzled experts for years.
Some believe the trees releasethem to communicate, while others say they could offer
protection from air pollution.
The team found the terpenes react in the air and formaerosols(气雾剂)．They help to
turn water vapour(蒸气)in the atmosphere into clouds.
Spracklen said the team"s computer models showedthat the aerosols doubled the
thickness of clouds about1,000 meters above the forests, and would reflect an extra5%
sunlight back into space.
He said, "It might not sound a lot, but that is quite astrong cooling effect. The climate
is such a finely balancedsystem that we think this effect is large enough to reduce
temperatures over quite large areas. It gives us anotherreason to preserve forests. "
Becausetreesrelease . moreterpenesinwarmerweather, the discovery suggests that
forests could act as anegative feedback (反馈) on climate, which slows the rise in
temperature.
B. growing more trees in the world
C. releasing aerosols above the forests
D. releasing terpenes in the air
B. They help thicken the clouds that reflect sunlight.
C. They make the temperature rise in cold northernarea s.
D. They help trees grow better.
B. reducing harmful chemicals in the air
C. producing a large amount of oxygen
D. reducing the earth"-s temperature
答案
举一反三
行病) of sleepiness in the nation."I can"t think of a single study that hasn"t found Americans getting less
sleep than they ought to," says Dr David.Even people who think they are sleeping enough would probably
be better off with more rest.
The beginning of our sleepdeficit crisis can be traced back to the invention of the light bulb a century
ago.From diary entries and our personal accounts from the 18th and 19th centuries,sleep scientists have
reached the conclusion that the average person used to sleep about 9.5 hours a night."The best sleep habits
once were forced on us,when we had nothing to do in the evening down on the farm,and it was dark." By
the 1950s and 1960s,the sleep schedule had been reduced dramatically,to between 7.5 and 8 hours,and
most people had to wake to an alarm clock."People cheat in their sleep,and they don"t even realize they"re
doing it," says Dr David."They think they"re okay because they can get by on 6.5 hours,when they really
need 7.5,8 or even more to feel ideally energetic."
Perhaps the most merciless robber of sleep,researches say,is the complexity of the day.Whenever
pressures from work , family, friends and community increase , many people consider sleep the least
expensive item on their programme."In our society,you"re considered dynamic if you say you need only
5.5 hours" sleep.If you"ve got to get 8.5 hours,people think you lack drive and ambition."
To determine the consequences of sleepdeficit , researchers have put subjects through a set of
psychological and performance tests requiring them,for instance,to add columns of numbers or recall a
passage read to them only minutes earlier."We"ve found that if you"re in sleepdeficit,performance suffers,"
says Dr David."Shortterm memory is weakened,as are abilities to make decisions and to concentrate."
B．The epidemic of sleepiness in the modern times.
C．The history of people"s sleeping patterns.
D．The minimum of our sleeping hours.
B．Some people can remain energetic with only 6.5 hours"sleep a night.
C．If they get 18.5 hours"sleep,people will be full of drive and ambition.
D．People"s metal power suffers if they are lacking in sleep.
B．they knew what was best for their health
C．they had no electricity
D．they were not so dynamic and ambitious as modern people are
B．the pressures of the day
C．the sufficient energy modern people usually have
D．loud noises in modern cities
B．Branches of knowledge studied in a school.
C．Persons or things being treated in a certain way or being experimented on.
D．Any member of a state apart from the supreme ruler.
adults around the world.
Sleep might be one answer to the problem.A new study has found that elementary school students
who slept too little were more likely to gain pounds.In the United States today, some 9 million children
over the age of 6 are obese (too fat).
Past studies have shown a link between sleeping less and weighing more, but scientists have had a
tough time determining"which_came_first, the_chicken_or_the_egg", says Julie C. Lumeng of the
University of Michigan in Ann Arbor.In other words, it hasn"t been clear whether kids who weigh too
much have trouble sleeping, or whether sleeping less leads to weight gain.Both scenarios (情况) seemed
equally possible.
To get a better idea of which causes which, Lumeng and his colleagues interviewed the parents of
785 third graders from around the United States.The parents answered questions about how well their
kids slept that year.Three years later, the parents answered the same questions.By sixth grade,18
percent of kids involved in the study were obese.The scientists found no relationship between weight
and the students"race or gender.It also didn"t matter how strict their parents were.Obesity struck all of
these groups equally.
Instead, sleep seemed to be the key factor.Over the 3 years of the study, the children averaged a
healthy 9.5 hours of sleep a night.Some kids, however, slept a lot more-or less-than others.For the sixth
graders, every hour of sleep above the 9.5hour average was linked to a 20 percent lower risk of being
obese.Sleep appeared doubly important for the third graders.Every extra hour of sleep they got was
linked to a 40 percent drop in obesity by third grade.
"I expected we"d find that this (sleep link with obesity) was just a_bunch_of_bunk, " says Lumeng,
a pediatrician.But their findings were convincing.No matter how her team looked at the link, "we
couldn"t make it go away."
1. According to the research, ________.
A. 9 million people in America have a weight problem
B. not enough sleep contributes to a gain in weight
C. sixth graders need more sleep than third graders
D. lack of sleep has become the most deadly killer
2. The statement "which came first, the chicken or the egg" suggests that________.
A. scientists are sure about the causes of children"s obesity
B. it"s easy to decide the cause and effect of this problem
C. scientists are still confused about the cause and effect of the problem
D. you"ll develop obesity if you eat chicken and eggs
3. Recent studies show that a child"s weight is influenced by the________.
A. amount of sleep
B. parents"attitude to him
C. race or gender
D. performance in school
4. The underlined part in the last paragraph most probably means something________.
A. acceptable
B. understandable
C. reliable
D. unreasonable
and cross deserts to bring Yemenis the goods more valuable than oil.It is one that only the rich can afford, with the supply regularly being cut off.Others must rely on scarce rain or charity to fight thirst.
Experts say Yemen is going to be the first country in the world to run out of water.The capital, Sanaa, will run out of drinking water as early as 2025, says a report by the World Bank.
Hannan, an 18yearold from Lahej, said that only the rich could prepare for cuts in supply."In a good
week we"ll have a water supply all week but then the following week there will be water only for a day or
two, " she said.
She and her husband, a factory worker, pay 3,000 riyals (99 yuan) for a week"s supply of water
from a touring water truck when the taps run dry.With an income of only 20,000 riyals (660 yuan) a
month, this means the family often spend half their money on water.
"There are a lot of people who can"t afford it and they have to rely on their neighbors to help, " she
said.
The average person in Yemen survives on onefifth of what the World Health Organization considers
to be enough water.
In Taiz, in the south, tap water is available only once every 45 days.In the mountainous Malhan district
in the north, women and children climb a 1,500m mountain to collect water from a spring, often in the
small hours to avoid long queues.
Yemen is located in Southwest Asia, bordering the Arabian and Red Sea.Yemeni people have lived
on scarce water supplies for thousands of years but that problem has been made serious by conflict in the
area, the fastgrowing population and the use of water to grow a drug called qat.With one of the world"s
highest rates of population growth-3.46 percent, Yemen is the poorest Arab country.
The government is considering desalinating (淡化) seawater, but this would be expensive and it may
now be too late.The only other solution is to cut down on farming, but that means importing even more
food.
1. The passage aims to________.
A. analyze the reasons why Yemen lacks water
B. suggest some solutions to the water issue in Yemen
C. present how serious the water problem is in Yemen
D. encourage the world to help Yemenis who are suffering from water shortages
2. When Hannan said that only the rich could prepare for cuts in supply, she meant that________.
A. rich people drank more water than the poor
B. rich people could buy water from the water trucks if there was a water supply cut
C. she had a rich neighbor who often helped her during water supply cuts
D. the rich were not affected by water supply cuts
3. Which of the following may be a reason why Yemen is short of water?
A. The country has had no rain for a long time.
B. The population of Yemen is growing fast.
C. The government has failed to reduce farming.
D. People can"t afford the water from government water trucks.
4. The best title for the passage is "________".
A. Never take water for granted
B. The water truck-the commonest sight in Yemen
C. The first country to run out of water in the world
D. No water for Yemen
strawberries in the winter or perfect tomatoes from Holland.In the space of a generation,we"ve become
accustomed to eating food that"s never grown roots in local soil.In fact,most produce (农产品) grown
in the United States travels an average of 1,500 miles before it gets sold.
Trucking,shipping and flying food from around the country and the globe has a very bad effect on the
environment and on public health.Take grapes for example.Every year,nearly 270 million pounds of
grapes arrive in California,most of them shipped from Chile to the Port of Los Angeles.Their 5,900mile
journey in cargo ships and trucks gives off 7,000 tons of global warming pollution each year,and enough
air pollution to cause dozens of asthma (哮喘) attacks and hundreds of missed school days in California.
The way we eat has a great influence on the health of the planet.By choosing to eat lower on the food
chain,and focusing on local and organic (有机的) produce,we can reduce global warming and air
pollution,avoid poisonous chemicals,support local farmers and enjoy fresh and tasty food.
People are rediscovering the benefits of buying local food.How your food is grown,stored,
transported,processed and cooked can all influence how it affects climate and the environment.
Transportationrelated influences are particularly important for imported food.NRDC calculated the
transportation influences of importing fresh produce and wine widely consumed in California.They
directly compared the climate and air quality influenced by importing the food instead of growing and
consuming it in California.Their analysis shows that-all else being equal-locally grown food is a better
choice.
1. From the passage we can learn that most produce sold at the grocery stores in the US________.
A. is grown by local farmers
B. is from foreign countries
C. comes from far away
D. is out of season
2. What would be the effect of transportation of food?
A. It pollutes the food during the transportation.
B. It makes the cost of the food much higher.
C. It makes the food less fresh and tasteless.
D. It causes air pollution and global warming.
3. Which of the following may have a bad effect on the health of the planet?
A. Eating higher on the food chain.
B. Eating locally grown food.
C. Eating more organic produce.
D. Eating fresh and tasty food.
4. The main purpose of the passage is________.
A. to help local farmers grow and sell their produce
B. to tell people that imported food is less healthy
C. to warn people of the harmfulness of food transportation
D. to get local people to reject the imported food
It is reported that around three hundred million plastic
bags are used by Chinese residents each day.________is known
to us all, our earth is crying________help because of
the serious white pollution.To our joy, all the shopping places
will be________(禁止) from providing free plastic bags from
June 1st this year.I________agree more to this.
A________we have known the bad effects of plastic
bags on our environment, yet we find it difficult to refuse
________-they are so convenient to us.Thanks to the
government, firm m________are to be taken to limit them.
I am sure that people will become used to g________
up the plastic bags.Only by________(改变) the way
we treat the earth can we________(形成)
a harmonious relationship with it.
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