American researchers have developed a technique that may become an important tool in fighting AIDS virus from attacking its target-cells in the body's defense system. When AIDS virus enters the blood, it searches for blood cells called T4 lymphocytes (淋巴细胞). The virus connects to the outside of T4 lymphocytes. Then it forces its way inside. There it directs the cells' genetic material to produce copies of the AIDS virus. This is how AIDS spreads.
Researchers think they may be able to stop AIDS from connecting to T4 ceils. When AIDS virus finds a T4 cell, it actually connects to a part of the cell called CD4 protein.
Researchers want to fool the virus by putting copies or clones of the CD4 protein into the blood. This way the AIDS virus will connect to cloned protein instead of the real ones. Scientists use genetic engineering methods to make the clones. Normally a CD4 protein remains on the T4 cell at all times; the AIDS virus must go to it.
In a new technique, however, the cloned CD4 protein is not connected to a cell. It floats freely, so a lot more can be put into the blood to keep the AIDS virus away from real CD4 protein on T4 cells. One report says the AIDS virus connects to cloned protein just as effectively as it connects to real protein. That report was based on tests with blood cells grown in labs. The technique is just now beginning to be tested in animals. If successful, it may be tested in humans within a year. The new technique can __________.
| A．cure AIDS |
| B．kill the AIDS virus |
| C．prevent the AIDS virus from spreading |
| D．produce new anti-AIDS cells |
When the AIDS virus enters the blood, it is reproduced by __________.
| A．itself |
| B．the blood cells |
| C．the CD4 protein |
| D．the genetic material of T4 lymphocytes |
The AIDS virus connects to cloned protein instead of the real CD4 protein because __________.
| A．cloned protein stays on the T4 cells |
| B．it connects to cloned protein more effectively |
| C．cloned protein is made by genetic engineering methods |
| D．cloned protein floats freely and many more can be put into the blood |
The best title for this passage is __________.
| A．AIDS—a deadly disease |
| B．A new technique in fighting AIDS |
| C．The spread of AIDS virus |
| D．The cloned CD4 protein |
Early one morning,more than a hundred years ago,an American inventor called Elias Howe finally fell asleep.He had been working all night on the design of a sewing machine but he had run into a very difficult problem: It seemed impossible to get the thread to run smoothly around the needle.
Though he was tired,Howe slept badly.He turned and turned.Then he had a dream.He dreamt that he had been caught by terrible savages whose king wanted to kill him and eat him unless he could build a perfect sewing machine.When he tried to do so,Howe ran into the same problem as before.The thread kept getting caught around the needle.The king flew into the cage and ordered his soldiers to kill Howe.They came up towards him with their spears raised.But suddenly the inventor noticed something.There was a hole in the tip of each spear.The inventor awoke from the dream,realizing that he had just found the answer to the problem.Instead of trying to get the thread to run around the needle,he should make it run through a small hole in the center of the needle.This was the simple idea that finally made Howe design and build the first really practical sewing machine.
Elias Howe was not the only one in finding the answer to his problem in this way.Thomas Edison,the inventor of the electric light,said his best ideas came into him in dreams.So did the great physicist Albert Einstein.Charlotte Bronte also drew in her dreams in writing Jane Eyre.
To know the value of dreams,you have to understand what happens when you are asleep.Even then,a part of your mind is still working.This unconscious(无意识的),but still active part understands your experiences and goes to work on the problems you have had during the day.It stores all sorts of information that you may have forgotten or never have really noticed.It is only when you fall asleep that this part of the brain can send messages to the part you use when you are awake.However,the unconscious part acts in a special way.It uses strange images which the conscious part may not understand at first.This is why dreams are sometimes called “secret messages to ourselves ”.According to the passage,Elias Howe was_________.
| A．the first person we know of who solved problems in his sleep |
| B．much more hard-working than other inventors |
| C．the first person to design a sewing machine that really worked |
| D．the only person at the time who knew the value of dreams |
The problem Howe was trying to solve was_________.
| A．what kind of thread to use |
| B．how to design a needle which would not break |
| C．where to put the needle |
| D．how to prevent the thread from getting caught around the needle |
Thomas Edison is spoken of because_________.
| A．he also tried to invent a sewing machine |
| B．he got some of his ideas from dreams |
| C．he was one of Howe's best friends |
| D．he also had difficulty in falling asleep |
Dreams are sometimes called “secret messages to ourselves” because _________.
| A．strange images are used to communicate ideas |
| B．images which have no meaning are used |
| C．we can never understand the real meaning |
| D．only specially trained people can understand them |
We know that many animals do not stay in one place.Birds,fish and other animals move from one place to another at a certain time.They move for different reasons:most of them move to find food more easily,but others move to get away from places that are too crowded.
When cold weather comes,many birds move to warmer places to find food.Some fishes give birth in warm water and move to cold water to feed.The most famous migration（迁移）is probably the migration of fish,which is called “Salmon”.This fish is born in fresh water but it travels many miles to salt water.There it spends its life.When it is old,it returns to its birthplace in fresh water.Then it gives birth and dies there.In northern Europe,there is a kind of mouse.They leave their mountain homes when they become too crowded.They move down to the low land.Sometimes they move all the way to the seaside,and many of them are killed when they fall into the sea.
Recently,scientists have studied the migration of a kind of lobster（龙虾）.Every year,when the season of bad weather arrives,the lobsters get into a long time and start to walk across the floor of the ocean.Nobody knows why they do this,and nobody knows where they go.
So,sometimes we know why humans and animals move from one place to another,but at other times we don’t.Maybe living things just like to travel.Most animals move from one place to another at a certain time to _________.
| A．give birth | B．enjoy warmer water |
| C．find food more easily | D．find beautiful places |
The mice in northern Europe move when _________.
| A．they give birth | B．the weather is bad |
| C．the place gets too crowded | D．they haven’t enough food |
The lobsters move _________.
| A．to the fresh water | B．to the deeper sea |
| C．at a certain time | D．to find more food |
Watch a baby between six and nine months old,and you will observe the basic idea of geometry（几何学）being learned.Once the baby has mastered the idea that space is three dimensional（空间的）,it reaches out and begins grasping various things,that the ideas of sets and numbers are formed.So far,so good.But now an ominous development takes place.The nerver fibers in the brain separate themselves in such a way that the baby begins to hear sounds very exactly.Soon it picks up language.And it is then brought into direct communication with grown-ups.From this point on,it is usually downhill all the way for mathematics,because the child now becomes exposed to all the rubbish words and beliefs of the born.Nature,having done very well by the child to this point,having permitted it the luxury（奢侈）of thinking for itself for eighteen months,now gives it up to the unreasonable conventions（惯例）and beliefs of society.But at least the child knows something of geometry and peaceful days,no matter what vicissitudes（兴衰变迁）it may suffer later on.The main reservoir of mathematical ability in any society is thus possessed by children who are about two years old,children who have just learned to speak freely.What does the passage mainly discuss?
| A．The impact（影响）of language on mathematics. |
| B．Children’s ability to learn languages. |
| C．How basic ideas of physics are learned? |
| D．Maths-learning strategies（策略）for babies. |
According to the passage,which of the following activities would teach a baby about geometry?
| A．Picking up a wooden block. | B．Recognizing the number 2. |
| C．Saying a rubbish word. | D．Looking at a distant word. |
Which of the following conclusions is true according to the writer?
| A．The language ideas used in early education interrupt mathematical reasoning. |
| B．It is hopeless to try to teach children mathematics after the age of two. |
| C．Language teaching should join some mathematical formulas（公式）. |
| D．Preschool education should emphasize society’s beliefs and conventions. |
Healthy knees aren’t the main consideration in choosing high heels,but new research says chunky heels are just as bad for the knees as spindly stilettos（细高跟鞋）.“It takes a long time to feel the effects of knee osteoarthritis（骨关节炎）—and once you do it,it is too late,”said Dr.Casey Kerrigan,leading researcher of the study and associate professor at Harvard Medical School’s department of physical medicine.“I compare it to smoking—one cigarette is not painful,but over a lifetime it is.Wide-heeled shoes feel comfortable,so women wear them all day long,”Kerrigan said.“They are better for your feet than stiletto heels,but just as bad for your knees.”
In the study,researchers had twenty women wear two pairs of shoes with three-inch heels,one with a narrow heel and the other with a thick one.The scientists compared how much pressure was put on the women’s knees by both types of shoes.The women also walked bare-foot to test normal pressure.The scientists found that both types of shoes applied equal amounts of pressure to the knees.Compared with walking barefoot,the heels increased pressure on the inside of the knee by 26 percent.Increased pressure on the knee eventually leads to arthritis,experts say.
The idea that high heels are bad for your health isn’t new—scientists have warned women for years that they contribute to problems ranging from corns to hammer toes,tendonitis,knee pain,sprained(扭伤)ankles and back problems.But in 1998,Kerrigan and a team of Harvard researchers were the first to link high heels and knee osteoarthritis,a painful joint disease that destroys cartilage(软骨)surrounding the knee.The first study looked only at stiletto heels,and Kerrigan said she wanted to study the chunky high-heeled shoes she noticed many women wearing.“This study confirms what we all intuitively（直觉地）know that high-heeled shoes of any kind are not good for our health,”said Dr.Glem Pfeffer,a San Francisco doctor and member of the American Academy of Orthopaedic Surgeons who was not connected to the study.We learn from the passage that women choose chunky heels because _________.
| A．they want to walk comfortably |
| B．chunky heeled shoes are cheaper than stiletto heeled pairs |
| C．chunky heels do less harm to knees |
| D．chunky heels are not painful at all |
The study mentioned in the second paragraph found that _________.
| A．pressure on the foot is caused by high heels |
| B．the pressure is abnormal while walking barefoot |
| C．arthritis is always caused by pressure on the knees |
| D．both types of shoes have the same harm to the knees |
It can be inferred from the passage that _________.
| A．people got to know the high heels are bad for health recently |
| B．people have known the high heels are bad for health for years |
| C．people haven’t known the high heels are bad for health yet |
| D．people will be warned that the high heels are bad for health soon |
Kerrigan’s late study looked at the chunky high-heeled shoes because _________.
| A．they feel more comfortable |
| B．they are related to knee osteoarthritis |
| C．they are worn by many women |
| D．they are different from stiletto heels |
The best title for the passage may be _________.
| A．Talking Healthy Knees into Consideration |
| B．High-heels Do Harm to Knees |
| C．Chunky Heels and Stiletto Heels |
| D．When Wearing High-heels |
More than 12 300 people were killed and tens of thousands left homeless after a powerful undersea earthquake unleashed giant tsunami waves that crashed into the coasts of south and southeast Asia.
The 8.9 magnitude earthquake that struck off the Indonesian island of Sumatra early on Sunday was the biggest in 40 years.It triggered waves that reared up into walls of water as high as 10 meters(30 feet) as they hit coastlines in Indonesia,Sri Lanka,India and Thailand.
Aid agencies rushed staff,equipment and money to the region,warning that bodies rotting in the water were already beginning to threaten the water supply for survivors.
Rescue workers also spoke of bodies still caught up on trees after being flung inland by the waves.
“I just couldn’t believe what was happening before my eyes,”Boree Carlson said from a hotel in the Thai resort of Phuket.
“As I was standing there,a car actually floated into the lobby and overturned because the current was so strong,”said the 45-year-old Swede.
“I heard an eerie sound that I have never heard before.It was a high pitched sound followed by a deafening roar,”said a 55-year-old Indian fisherman who gave his name as Chellappa.
“I told everyone to run for their life.”
In Indonesia,an archipelago of 17 000 islands,one official said nearly 4500 people had died.The worst affected area was Bands Aceh,the capital of Aceh Province,where 3000 were killed.More than 200 prisoners escaped from a jail when the tsunami knocked down its walls.In Sri Lanka（斯里兰卡）,the death toll also reached 4500 and 1 million people,or 5 percent of its population,were affected.It was the worst natural disaster to hit Sri Lanka.Hundreds of thousands of Sri Lankans sheltered in schools and temples overnight,and officials expected the death toll to rise further once rescuers resumed searches after daybreak.In southern India,where at least 3000 were estimated to have died,beaches were littered with submerged cars and wrecked boats.Shanties on the coast were under water.
Thai government officials said at least 392 bodies had been retrieved and they expected the final toll to approach 1000.
The earthquake,of magnitude 8.9 as measured by the U.S. Geological Survery (news-web sites),struck at 7:59 a.m.(1959EST).It was the world’s biggest since 1964,said Julie Martinez at the USGS(news-web sites).
The tsunami was so powerful it smashed boast and flooded areas along the east African coast,3728 miles away.What does the underlined word “tsunami” probably mean?
| A．Tidal wave. | B．Wave. |
| C．Earthquake. | D．A man who kills many persons. |
What does the passage mainly talk about？
| A．Asian tsunami kills many people,and many more become homeless. |
| B．An earthquake happens. |
| C．The tsunami was so powerful that it smashed boats and people. |
| D．It was the biggest earthquake in 40 years. |
The sea waves hit coastlines in _________.
| A．Indonesia | B．Sri Lanka | C．India and Thailand | D．All of above |
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