Most people around the world are right-handed. This also seems to be true in history. In 1799, scientists studied works of art made at different times from 1,500 B.C. to the 1950s. Most of the people shown in these works are right-handed, so the scientists guessed that right-handedness has always been common through history. Today, only about 10% to 15% of the world’s population is left-handed.

 Why are there more right-handed people than left-handed ones? Scientists now know that a person’s two hands each have their own jobs. For most people, the left hand is used to find things or hold things. The right hand is used to work with things. This is because of the different work of the two sides of the brain. The right side of the brain, which makes a person’s hands and eyes work together, controls the left hand. The left-side of the brain, which controls the right hand, is the centre for thinking and doing problems. These findings show that more artists should be left-handed, and studies have found that left-handedness is twice as common among artists as among people in other jobs.

 No one really knows what makes a person become left-handed instead of right-handed. Scientists have found that almost 40% of the people become left-handed because their main brain is damaged when they are born. However, this doesn’t happen to everyone, so scientists guess there must be another reason why people become left-handed. One idea is that people usually get right-handed from their parents. If a person does not receive the gene (基因) for right-handedness, he/she may become either right-handed or left-handed according to the chance and the people they work or live with.

 Though right-handedness is more common than left-handedness, people no longer think left-handed people are strange or unusual. A long time ago, left-handed children were made to use their right hands like other children, but today they don’t have to.

 We have known for a long time that flowers of different plants open and close at different time of day. Yet no one really understands why flowers open and close like this at particular times. It is not as simple as we might think, as new experiments have shown. In one experiment, flowers were kept in darkness. We might expect that the flowers, without any information about the time of the day, did not open as they usually do. In fact, they continued to open at their usual time. This shows that they have some mysterious (神秘的) way of knowing the time.

    Their sense of time does not depend on information from the outside world; it is, so to speak, inside them, a kind of “inner clock”. This discovery may not seem to be very important. However, it was later found that not just plants but also animals including man have this “inner clock” which controls working of their bodies and their activities.

Human beings, then, are also controlled by this mysterious power. Whether we wish it or not, it affects such things in our life as our need for sleep, our need for food. And our ability to concentrate(集中).

What will the weather be like? Some people say they can know what the weather will be like from birds. They kook at birds. When they see birds fly high out to the sea, they say it will be a nice day. For birds donˈt like to fly out when it could rain. When the weather will be bad, sea birds turn back and stay on shore.

A big wind may come with a rain. Birds do not like to fly in a big wind. They may sit in a tree when rain is on the way.

Some people look at different animals on a farm. Other animals can alsotellthe weather. A chicken may make a big noise when rain is on the way. It may run here and there. A frog can show the weather, too. A frog will make a big noise when rain is on the way. It will stay in the water. On a nice day, it will come out up high out of the water.

“Life is speeding up. Everyone is getting unwell.”

This may sound like something someone would say today. But in fact, an unknown person who lived in Rome in AD（公元） 53 wrote it.

We all love new inventions. They are exciting, amazing and can even change our lives. But have all these developments really improved the quality of our lives?

Picture this. You’re rushing to finish your homework on the computer. Your mobile phone rings, a QQ message from your friend appears on the screen, the noise from the television is getting louder and louder. Suddenly the computer goes blank and you lose all your work. Now you have to stay up all night to get it done. How happy do you feel?

Inventions have speeded up our lives so much that they often leave up feeling stressed and tired. Why do you think people who live far away from noisy cities, who have no telephones, no cars, not even any electricity often seem to be happier? Perhaps because they live simpler lives.

One family in the UK went “back in time” to see what life was like without all the inventions we have today. The grandparents, with their daughter, and grandsons Benjamin, 10 and Thomas, 7, spent nine weeks in a 1940s house. They had no washing machine, microwave（微波炉）, computer or mobile phones.

The grandmother, Lyn, said, “The more things you have, the more difficult life becomes.” The boys said they fought less. Probably, they said, because there was less to fight over, such as their computer. Benjamin also noticed that his grandmother had changed from being a “trendy（赶时髦的）, beer-drinking granny”, to one who cooked things.

根据短文内容，选择正确答案。

A kind of little cars may take the place of (取代)today’s big ones many years later. If everyone drives such cars in the future, there will be less pollution in the air. There will also be more space for parking in cities, and the streets will be less crowded.

The little cars of the future will cost less. Driving will be safer, too, since these little cars can go only 65 kilometers an hour. The cars of the future will be fine for going around a city, but they will not be useful for a long way. Little cars will go 450 kilometers before they need to stop for more gasoline (汽油). If big cars are still used with the small ones, two kinds of roads will be needed in the future. Some roads will be needed for the big, faster cars and other roads will be needed for the small, slower ones.

根据短文内容，选择正确答案。

Many people think that the hump* of the camel is full of water. They think this is the reason that camels do not have to drink very often in the desert*, but they are not right. A camel’s hump is not full of water. It is fat*. The camel’s body can use the fat later when it is hungry, but it does not help the camel go for a long time without* drinking. A camel can do this because it does not sweat* very much.

When people and most other animals get hot, they sweat. Sweat is mostly water from the body. So when people sweat, they lose water and soon have to drink. If they don’t drink water, they die. When a camel gets hot, it does not sweat very much, so it does not lose much of the water in its body. It does not need to drink very often.

LONDON—Scientists have found an unusual way to prevent our planet from overheating: move it to a cooler spot. All you have to do is to send a few comets (彗星) in the direction of Earth, and its orbit (轨道)wil l be changed. Our world will then be sent moving into a safer older part of the solar system.

This idea for improving our climate comes from a group of US NASA (美国航空航天局) engineers and American astronomers. They say their plan could add another six billion years to the useful lifetime of our planet—hopefully doubling its working life.

The plan put forward by Dr. Laughlin, and his colleagues Don Korycansky and Fred Adams, needs carefully directing a comet or asteroid (小行星) so that it passes close by our planet and sends some of its gravitational energy (重力势能) to Earth.

“Earth’s orbital speed would increase as a result and we would move to a higher orbit away from the sun,” Laughlin said.

Engineers would then direct their comet so that it passed close to Jupi ter(木星) or Saturn (土星). The comet would pick up energy from one of these giant planets. Later its orbit would bring it back to Earth, and the process would be repeated.

In the short term, the plan provides an ideal way to worldwide warming, although the team was actually worried about a much greater danger. The sun is certain to heat up in about a billion years and so “seriouslycompromise” our biosphere (生物圈)—by cooking us.

That’s why the group decided to try to save Earth.

The plan has one or two worrying sides, however. For a start, space engineers would have to be very careful about how they directed their asteroid or comet towards Earth. The smallest miscalculation (误算)in orbit could fire it straight at Earth—with deadly results.

There is also the question of the moon. As the present issue of Scientific American magazine points out, if Earth was pushed out of its present location, it is “most likely the moon would be stripped(剥离)away from Earth,” it states. This would greatly change our planet’s climate.

Sitting on a chair all day in school can make anyone want to move around. So, more and more teachers are letting students have a ball. By sitting on exercise balls instead of chairs, teachers find students’ attention improve.

Peter, a fifth-grade teacher in West Virginia, the USA, has been using balls as chairs since December 2010.“The students love them”, he says. Peter took a survey of his students. He found that 80% of the students thought sitting on the balls helped them pay more attention to what they were learning.

The manager(经理), Mary, felt so strongly about the use of balls as chairs, she encourages the use of the balls. She hopes not only teachers but also students know how to use them. “Our products(产品) are used in 24 states(州), three provinces(省) in Canada, Puerto Rico and Japan,” says Mary. “Research(调查) shows that sitting on the balls makes them sit up straighter,” says Mary, “but it feels not boring.” Because the students are moving, so the kids have more energy and can keep longer.

“Besides, they're fun.” says Peter.

Maybe you are an average (一般的) student. You probably think you will never be a top student (尖子生). However, anyone can become a better student if he or she does his or her best. Here are some tips (技巧) to help you.

Plan your time carefully. You should plan your time for such things aseating, sleeping and dressing. Then make a good, regular time for studying, but don’t forget to set enough time for entertainment (娱乐).

Keep your study quiet and clean. The study should have a desk, a chair and some study materials (资料), but no games, no radio and no television! When you sit down to study, you can put your heart into it. Make good use of your time.

Listen to everything that the teacher says. Listening carefully in class means less work later. Taking notes will help you remember what the teacher says.

After you get home from school, go over your notes. Review the important points. If you know what your teacher is going to discuss next day, read the material. It will help you study better.

Develop a good attitude (态度) to tests. The purpose (目的) of a test is to show what you have learned about a subject. It helps you know what you are not good at. The world will still go on even if (即使) you fail (不及格) in a test, so don’t be too worried.

A peaceful mind（平静心态的） is very important for our effectiveness（效率）. It keeps us calm, no matter what the situation is, and it allows us to stay happy during the day. So, here, I would like to share some ways to have a “mind like water”, a state of mind that is as peaceful as calm water. Pick the ones that work for you.

◆Listen to your heart

Your heart tells you what is the right thing to do. It is where your deepest values（价值观） live. Following what your heart says helps you be true to yourself, and that helps you get a peaceful mind. So learn to listen more to your heart, and do what it tells you to do.

◆ Don’t take in too much information

Getting more information often means introducing more noise into your mind. That’s why not taking in too much information is important for a calm and peaceful mind. You should take in no more information than necessary.

◆ Slow down（放慢速度）

Whatever you do, you do not need to be in a hurry. Doing so will only take you faster in the wrong direction . First of all, you need to know the right direction to go. Slow down so that you can hear the voice of your heart.

Don’t think too much about yourself and do something for other people

We usually think about our own needs and problems most of the time. But self-centered（自我为中心的） thoughts can’t bring peace into our mind. Instead, it may make us feel stressed,. So don’t think too much about yourself, forget yourself for a while. Think about other people more often and think what you can do for others, then do it. Giving will make you happy and give you peace of mind.