Two­thirds of the world's major rivers have now been disrupted with more than 50,000 dams in an attempt to  store water and provide power.In the US，there are more than 85,000 dams，disrupting large and small rivers，and in most cases transforming natural flow.The most famous of these，the Hoover Dam，constructed in the 1930s，is mainly responsible for the fact that the Colorado River no longer reaches the ocean.
Dams，besides all their attractive benefits，also have negative impacts.Creating a reservoir means a large area must be flooded.Communities may lose their land，houses and culturally important sites.
Environmentally，the new reservoir can be a paradise for wildlife，especially birds；however，it can cause greenhouse gas emissions and poison the water.Also，the dramatic rise and fall of water levels during dam releases is too extreme for plants and animals to cope with，resulting in dead zones around the shores of reservoirs.Fish that lay their eggs in the shallows，for example，may find a few hours later that those sites are high and dry.
Downstream(在下游方向)of a dam，the flow may be reduced so that farmers cannot irrigate their fields.Many rivers run through national borders，which may cause conflict over precious water.Disputes have been continuing between India and Pakistan，and Turkey，Syria and Iraq，for example.
Dams don't just block the flow of water.They also prevent fish migrations，and dams are a barrier to sediment(沉淀物)flows.Instead of rushing downriver，sediments get backed up against the dam wall，which causes the reservoir level to increase over time.However，sediments which are rich in nutrients have become a problem.The fertility of the entire system can be influenced，with soils lost during seasonal rains not being replaced.
Perhaps the biggest problem can be seen in deltas，which are sinking into the oceans.Groundwater is being extracted to feed the city，causing the city to sink，and sediments washed away by the ocean are no longer being replaced.The result is that sea level rises in cities from Shanghai to Alexandria.
【小题1】The Hoover Dam is mentioned in the passage in order to show________.

A．dams play an important role in our life

B．dams have impacted the flow of the rivers

C．dams make people lose their land and houses

D．dams have many benefits as well as side effects

【小题2】What effects does creating a reservoir have on people's life?
a．People will see fewer birds on the sides of the rivers.
b．Farmers will have less water to irrigate their fields.
c．Visitors can't visit some cultural relics any more.
d．More conflicts and wars over water will break out.
e．More kinds of fish will become extinct in future.

A．a，c	B．c，e
C．b，e	D．b，c

【小题3】With many dams built across the rivers，fish ________.

A．will find more places to lay their eggs

B．will face a dangerous habitat

C．will be fed on more sediments rich in nutrients

D．will find it easier to deal with the rise of water

【小题4】How can dams influence large cities like Shanghai?

A．Their entire system will be influenced.

B．The rainy season will last longer.

C．They will lie below sea level in future.

D．Rich soils will be washed away.

【小题5】What does the passage mainly talk about?

A．Environmental loss of dams.

B．Cultural loss of dams.

C．Economic gain of dams.

D．Environmental benefits of dams.

Mulch is a protective cover of material that is spread on top of soil.It is usually made out of organic material, like crop waste.Farmers may keep the remains of maize or other crops on top of the soil.This creates mulch on the soil surface.The plant remains help protect the soil against wind and water damage.Mulching is one of the best things people can do for their plants.It also helps keep the soil from getting dry, and reduces the need for watering plants.It also limits temperature changes in the soil.And it stops unwanted plants, or weeds，from growing.
Organic mulch improves the condition of soil.As the mulch breaks down, it provides material which keeps the soil from getting hard.This improves the growth of roots and increases the movement of water through the soil.It also improves the ability of the soil to hold water. Organic mulch contains nutrients for plants.It also provides a good environment for earthworms and other helpful organisms in the soil.
It is easy to find organic mulch materials.Cut­up leaves and small pieces of tree bark can be used.Grass cuttings are also a good mulch for plants. Mulch from newspapers works well in controlling weeds.
The best time to add mulch depends on your goal.Mulch provides a thick barrier between the soil and the air.This helps to reduce temperature changes in the soil. As a result，mulched soil will be cooler than other soil in the summer.In winter, the mulched soil may not freeze as deeply as other soil.The best time is after the ground has frozen, but before the coldest weather arrives.Spreading mulch before the ground has frozen may attract small animals searching for a warm place to spend the winter.Delaying the spreading should prevent this problem.The animals will probably find another place to live.
【小题1】The author tells us the following EXCEPT________.

A．what mulch is and its benefits

B．the best time to add mulch

C．what can be mulched on the soil surface

D．the bad effects of mulch

【小题2】The following can be used as organic materials to make mulch EXCEPT________.

A．tree barks	B．cut­up leaves
C．grass cuttings	D．plastic

【小题3】Which of the following is the benefit of mulch?

A．Protecting the soil against wind and water damage.

B．Keeping the soil wet and reducing the need for watering plants.

C．Reducing temperature changes in the soil and stopping unwanted weeds growing.

D．All of the above.

【小题4】The main idea of Paragraph 2 is that organic mulch can________.

A．improve the condition of soil

B．improve the ability of the soil to hold water

C．provide a good environment for earthworms

D．improve the growth of roots and increase the movement of water through the

soil
【小题5】From the last paragraph, we know ________.

A．the best time to add mulch is in spring and summer

B．the best time to add mulch is after the coldest weather arrives

C．the best time to add mulch depends on weather

D．choosing the best time to add mulch can avoid attracting small animals

It's hardly surprising that weather is a favorite topic for so many people around the world—it affects where we choose to live, what we wear, our moods, and perhaps even our national characteristics.Studies have shown that changeable weather can make it difficult to concentrate, cloudy skies slow down reaction, and hot，dry winds make many people bad­tempered.
If you live in a place like Britain, where the weather seems to change daily if not hourly，you could be forgiven for thinking that the weather is random.In fact the weather is controlled by systems which move around areas of the globe.In the UK the weather depends on depressions (低压气流), often called lows，and anticyclones(反气旋)，also known as highs.These systems start in the Atlantic Ocean, and make their way across the British Isles from the west to the east.Highs bring sunny weather, while lows bring rain and wind.In modern times, human activities seem to be altering weather patterns.Gases produced by heavy industry change the temperature of the earth's surface，and affect cloud formation.Some researchers say that factories in Europe and North America may have been one of the causes of the droughts in Africa in the 1980s.
The human race has always tried to guess the weather，especially in areas of the world where there are frequent changes.Traditional rhymes point to early attempts to identify weather patterns; popular poems include：
Red sky at night, shepherd's delight；red sky in the morning, shepherd's warning.
Flies will swarm before a storm.
Rain before 7，clear by 11.
While folk wisdom can provide a guide to help forecast weather, today's methods of prediction increasingly rely on  technology.Satellites, balloons，ships, aircrafts and weather centers with sensitive monitoring equipment, send data to computers.The data is then processed, and the weather is predicted.However，even this system cannot predict weather for longer than about a week.
【小题1】When weather keeps changing，________.

A．people become bad­tempered

B．people's reaction slows down

C．people find it hard to focus on their work

D．people find it easy to focus on their work

【小题2】The weather in Britain is________.

A．random	B．moist
C．depressing	D．satisfying

【小题3】According to a traditional rhyme, if there is a red sky at night, the next day will be________.

A．windy	B．rainy
C．fine	D．snowy

【小题4】Which of the following statements is TRUE?

A．Anticyclones often bring rain and wind.

B．Weather forecasting has been done for a long time.

C．Weather could never be predicted.

D．Modern methods of weather prediction are developed from folk wisdom.

【小题5】What is mainly talked about in the second paragraph?

A．Changes in weather.

B．Weather in Britain.

C．African droughts.

D．Research on weather.

The United States is not part of the Kyoto Protocol.But since 2005 more than 1,000 mayors across the country have agreed to sign their own version of the protocol.
It is called the United States Conference of Mayors' Climate Protection Agreement.Local leaders have agreed to follow the suggestions of the Kyoto Protocol in their communities.They have also agreed to urge state and federal governments to follow these suggestions.One goal is to reduce air pollution to the 1990 levels by 2012.
A “green” city might work on several kinds of environmental goals and programs.These include air quality，reducing electricity use, green building, public health, the reuse of materials, water quality and clean transportation.
The Natural Resources Defense Council works to protect the environment through action, law and science.One of its online projects is called Smarter Cities, which lists some cities that have made important environmental steps.
Washington，D.C.is also a leading city for green roofs，with over 92,000 square meters of green rooftops.The city also launched a program called “Skip the Bag，Save the River.”Stores charge people a five­cent  tax for using plastic or paper shopping bags instead of reusable bags.Money from the tax will be used to clean up a local river.
New York City is using water as a renewable energy source.For several years, the city has experimented with water in the East River to create energy.Officials operating the program recently asked for permission to put into place 30 river turbine devices.
The people of Portland, Oregon are among the top recyclers in the nation.People living there recycle over half of the waste they throw out.The city has also worked to provide green transportation by providing safe bike paths and free parking spaces where electric cars can get recharged.
In Oakland, California, you can ride on one of several public hydrogen­powered(氢气作燃料的) buses.These buses release zero pollution into the air.However，they cost about five times more than common buses.
【小题1】The United States Conference of Mayors' Climate Protection Agreement is aimed at________.

A．reducing energy use

B．reducing air pollution

C．improving public health

D．reusing waste materials

【小题2】Why are shoppers charged a five­cent tax for buying shopping bags?

A．To clean a local lake that has been polluted.

B．To get enough money for the green roof project.

C．To prevent shoppers from using reusable bags.

D．To collect money for an environmental project.

【小题3】New York City is cited as an example of________.

A．building green rooftops

B．making transportation clean

C．being good at recycling waste

D．using renewable energy source

【小题4】Which of the following cities encourage citizens to use bicycles?
A．Washington，D.C.　   B．New York.
C．Portland.　  D．Oakland.
【小题5】One obvious disadvantage of adopting hydrogen­powered buses is________.

A．its high cost	B．side effect
C．zero pollution	D．large space

Here is an astonishing and significant fact：Mental work alone can’t make us tired.It sounds absurd.But a few years ago，scientists tried to find out how long the human brain could labor without reaching a stage of fatigue (疲劳)．To the amazement of these scientists，they discovered that blood passing through the brain，when it is active，shows no fatigue at all! If we took a drop of blood from a day laborer，we would find it full of fatigue toxins(毒素) and fatigue products.But if we took blood from the brain of an Albert Einstein，it would show no fatigue toxins at the end of the day.
So far as the brain is concerned，it can work as well and swiftly at the end of eight or even twelve hours of effort as at the beginning.The brain is totally tireless.So what makes us tired?
Some scientists declare that most of our fatigue comes from our mental and emotional(情感的) attitudes.One of England’s most outstanding scientists，J.A.Hadfield，says，“The greater part of the fatigue from which we suffer is of mental origin.In fact，fatigue of purely physical origin is rare.”Dr.Brill，a famous American scientist，goes even further.He declares，“One hundred percent of the fatigue of a sitting worker in good health is due to emotional problems.”
What kinds of emotions make sitting workers tired? Joy? Satisfaction? No! A feeling of being bored，anger，anxiety，tenseness，worry，a feeling of not being appreciated－those are the emotions that tire sitting workers.Hard work by itself seldom causes fatigue.We get tired because our emotions produce nervousness in the body.
【小题1】What surprised the scientists a few years ago?

A．Fatigue toxins could hardly be found in a laborer’s blood.

B．Albert Einstein didn’t feel worn out after a day’s work.

C．The brain could work for many hours without fatigue.

D．A mental worker’s blood was filled with fatigue toxins.

【小题2】According to the author，which of the following can make sitting workers tired?

A．Challenging mental work.

B．Unpleasant emotions.

C．Endless tasks.

D．Physical labor.

【小题3】What’s the author’s attitude towards the scientists’ ideas?

A．He agrees with them.

B．He doubts them.

C．He argues against them.

D．He hesitates to accept them.

【小题4】We can infer from the passage that in order to stay energetic，sitting workers need to ________.

A．have some good food

B．enjoy their work

C．exercise regularly

D．discover fatigue toxins

You can’t always predict a heavy rain or remember your umbrella.But designer Mikhail Belyaev doesn’t think that forgetting to check the weather forecast before heading out should result in you getting wet.That’s why he created Lampbrella，a lamp post with its own rain­sensing umbrella.
The designer says he come up with the idea after watching people get wet on streets in Russia.“Once，I was driving on a central Saint Petersburg street and saw the street lamps lighting up people trying to hide from the rain.I thought it would be appropriate to have a canopy(伞篷)built into a street lamp，”he said.
The Lampbrella is a standard­looking street lamp fitted with an umbrella canopy.It has a built­in electric motor which can open or close the umbrella on demand.Sensors(传感器)then ensure that the umbrella offers pedestrians shelter whenever it starts raining.
In addition to the rain sensor，there’s also a 360°motion sensor on the fiberglass street lamp which detects whether anyone is using the Lampbrella.After three minutes of not being used the canopy is closed.
According to the designer，the Lampbrella would move at a relatively low speed，so as not to cause harm to the pedestrians.Besides，it would be grounded to protect from possible lightning strike.Each Lampbrella would offer enough shelter for several people.Being installed(安装) at 2 meters off the ground，it would only be a danger for the tallest of pedestrians.
While there are no plans to take the Lampbrella into production，Belyaev says he recently introduced his creation to one Moscow Department，and insists his creation could be installed on any street where a lot of people walk but there are no canopies to provide shelter.
【小题1】For what purpose did Belyaev create the Lampbrella?

A．To predict a heavy rain.

B．To check the weather forecast.

C．To protect people from the rain.

D．To remind people to take an umbrella.

【小题2】What do we know from Belyaev’s words in Paragraph 2?

A．His creation was inspired by an experience.

B．It rains a lot in the city of Saint Petersburg.

C．Street lamps are protected by canopies.

D．He enjoyed taking walks in the rain.

【小题3】Which of the following shows how the Lampbrella works?

A．motor→canopy→sensors

B．sensors→motor→canopy

C．motor→sensors→canopy

D．canopy→motor→sensors

【小题4】What does Paragraph 5 mainly tell us about the Lampbrella?

A．Its moving speed.

B．Its appearance.

C．Its installation.

D．Its safety.

【小题5】What can be inferred from the last paragraph?

A．The designer will open a company to promote his product.

B．The Lampbrella could be put into immediate production.

C．The designer is confident that his creation is practical.

D．The Lampbrella would be put on show in Moscow.

German study suggests that people who were too optimistic about their future actually faced greater risk of disability or death within 10 years than those pessimists who expected their future to be worse.
The paper，published this March in Psychology and Aging，examined health and welfare surveys from roughly 40,000 Germans between ages 18 and 96.The surveys were conducted every year from 1993 to 2003.
Survey respondents (受访者) were asked to estimate their present and future life satisfaction on a scale of 0 to 10，among other questions.
The researchers found that young adults (age 18 to 39) routinely overestimated their future life satisfaction，while middle­aged adults (age 40 to 64) more accurately predicted how they would feel in the future.Adults of 65 and older，however，were far more likely to underestimate their future life satisfaction.Not only did they feel more satisfied than they thought they would，the older pessimists seemed to suffer a lower ratio (比率) of disability and death for the study period.
“We observed that being too optimistic in predicting a better future than actually observed was associated with a greater risk of disability and a greater risk of death within the following decade，”wrote Frieder R．Lang，a professor at the University of Erlangen­Nuremberg.
Lang and his colleagues believed that people who were pessimistic about their future may be more careful about their actions than people who expected a rosy future.
“Seeing a dark future may encourage positive evaluations of the actual self and may contribute to taking improved precautions (预防措施)，”the authors wrote.
Surprisingly，compared with those in poor health or who had low incomes，respondents who enjoyed good health or income were associated with expecting a greater decline.Also，the researchers said that higher income was related to a greater risk of disability.
The authors of the study noted that there were limitations to their conclusions.Illness，medical treatment and personal loss could also have driven health outcomes.
However，the researchers said a pattern was clear.“We found that from early to late adulthood，individuals adapt their expectations of future life satisfaction from optimistic，to accurate，to pessimistic，”the authors concluded.
【小题1】According to the study，who made the most accurate prediction of their future life satisfaction?

A．Optimistic adults.

B．Middle­aged adults.

C．Adults in poor health.

D．Adults of lower income.

【小题2】Pessimism may be positive in some way because it causes people________.

A．to fully enjoy their present life

B．to estimate their contribution accurately

C．to take measures against potential risks

D．to value health more highly than wealth

【小题3】How do people of higher income see their future?

A．They will earn less money.

B．They will become pessimistic.

C．They will suffer mental illness.

D．They will have less time to enjoy life.

【小题4】What is the clear conclusion of the study?

A．Pessimism guarantees chances of survival.

B．Good financial condition leads to good health.

C．Medical treatment determines health outcomes.

D．Expectations of future life satisfaction decline with age.

【小题1】What is the colour of blood in a vein near the surface of the skin?

A．Blue.	B．Light yellow.
C．Red.	D．Dark reddish purple.

【小题2】Why do some old people look a little shrunken as they age?

A．Because their spine is in active use.

B．Because they are more easily affected by gravity.

C．Because they keep growing backwards.

D．Because their spine becomes more bent.

【小题3】Which of the following statements about our brain is true?

A．In the long run，our brain probably works harder than our heart.

B．When our brain senses the spinning，we will feel dizzy.

C．The brains of the other mammals are as complex as those of humans.

D．Our feelings and emotions come from the most developed area in our brain.

【小题4】What is the main purpose of the selection?

A．To give advice on how to stay healthy.

B．To provide information about our body.

C．To challenge new findings in medical research.

D．To report the latest discoveries in medical science.

Scientists who discovered a new way of generating electricity from water say they may have come across an alternative source of clean energy to rival wind and solar power.
The breakthrough, which scientists say is the first new way to generate electricity in 160 years, could lead to batteries that use water instead of poisonous substances.
The scientists made the discovery when they were investigating what happens when tap water is forced through extremely narrow glass tubes. Water squeezed down the tubes, each of which was narrower than a tenth the thickness of a human hair, generating a small electric current that ran the length of the tube. To produce a larger electric current, the team tried forcing water through a glass water filter(滤水器)that contained thousands of narrow channels lined up side by side. “When we took a syringe(注射器)of water and squeezed it through the filter, we got enough power to light a light bulb,” said Larry Kostiuk of the University of Alberta in Canada. “The harder you push the syringe, the more electric current you get.”
The current is produced because of an effect in the glass tubes. When they are filled with water, positively charged ions(阳离子)fixed in the tubes are washed away, leaving a slight negative charge on the glass surface. When water is then forced along the tube, the surface repels negatively charged ions in the water while positively charged ions are attracted down the tube. The result is a net flow of positively charged ions that sets up an electric current.
According to Dr Kostiuk, no one has ever thought to use water to produce electricity in this way. “The last time someone came up with a way of generating electricity was Michael Faraday in 1839,” he said. “So this is the first new way of generating electricity in 160 years, which is why we are so excited about it.”
Dr Kostiuk says water batteries might one day be used to power mobile phones and calculators, but admitted that the engineering challenges might make other applications more realistic. “You’d need to be sure it wouldn’t leak, and you’d need to make sure it wouldn’t freeze,” he said.
More likely would be to install the electricity-generating devices where water is already being pumped, such as at city water filtration sites, he said. “It could compete with wind and solar power,” he added.
【小题1】What does the passage mainly want to tell us about?

A．A kind of solar power discovered by scientists.

B．A kind of new energy source found in tap water.

C．The breakthrough to generate electricity 160 yeas ago.

D．A kind of new battery invented without poisonous substances.

【小题2】The underlined word “repels” in Paragraph 4 is closest in meaning to _________.

A．rejects

B．identifies

C．attracts

D．rebels

【小题3】Why were the scientists extremely happy about their new discovery?

A．They were the first to find a new way to produce electricity.

B．They could make an electric current to light a light bulb.

C．Their discovery could be used to invent water batteries.

D．Their discovery was made 160 years earlier than Faraday’s.

【小题4】What can we infer about potential water batteries?

A．They must be used to power mobile phones and calculators.

B．They have some possible disadvantages like water leaking.

C．They would be needed greatly at city water filtration sites.

D．They would be better than wind and solar power.

“iPhone 5”, the tallest thing to happen to iPhone since iPhone

We don’t want to change your phone, we want to make you say, “Wow, that is a bigger change than I expected”. “iPhone 5” is a result of that desire to surprise.
It’s been completely redesigned. For the first time ever, we’ve increased the size of display (显示) by making the screen taller but not wider.
You can see more of your content without the need to scroll. We are making scrolling the thing of the past. It is more comfortable to use and reduces tiredness from scrolling when you read long documents.
Even with the larger display, it is the thinnest iPhone we ever built. To achieve the design this tall, we have to look at it and completely redesign the architecture inside. It’s 18% thinner and 79.5% taller than the previous iPhone. It makes everything you do on “iPhone5” easier. No more hidden menus, no confusing gestures. Everything is right at your fingertips.
The panorama feature (全景拍照) is simply awesome. The ultra HD (超高清) widescreen display lets you get your entire shot in a single snap (快门). You can also use its creative design for picture stabilization.
With an iPhone this tall, reception of signals has never been better. And of course, all your favorite applications are still available. In fact you will find your old favorites also benefit from the new experiencing handsome ultra HD widescreen. We found while many previous iPhone owners were using Facetime, they only used it for the faces. That’s why we are introducing Bodytime. With its ultra HD widescreen display, Bodytime lets you see a person’s entire body.
It took all of our learning and all of our thinking to realize something so simple, so clear, and yet so tall.
And I wish your pocket were tall enough to hold such a perfect invention!
【小题1】How is the screen of “iPhone 5” different from the previous ones?

A．Wider.

B．Taller.

C．Easier.

D．Thinner.

【小题2】What does the underlined word “scroll” probably mean?

A．Update the webpage.	B．Download new documents.
C．Refresh the content.	D．Move the content upward.

【小题3】What can we infer about “iPhone 5” from the passage?

A．It is really necessary for you to hide menus.

B．The reception of signals is bad due to its length.

C．Bodytime is popular with previous iPhone owners.

D．New applications of “iPhone 5” are unbelievable.

【小题4】“iPhone 5” is introduced in a(n) ________ way in this passage.

A．humorous

B．objective

C．scientific

D．serious