Social change is more likely to occur in societies where there is a mixture of different kinds of people than in societies where people are similar in many ways. The simple reason for this is that there are more different ways of looking at things present in the first kind of society. There are more ideas, more disagreements in interest, and more groups and organizations with different beliefs. In addition, there is usually a greater worldly interest and greater tolerance in mixed societies. All these factors tend to promote social change by opening more areas of life to decision. In a society where people are quite similar in many ways, there are fewer occasions for people to see the need or the opportunity for change because everything seems to be the same. And although conditions may not be satisfactory, they are at least conventional and generally agreed.

    Within a society, social change is also likely to occur more frequently and more readily in the material aspects of the culture than in the non-material, for example, in technology rather than in values; in what has been learned later in life rather than what was learned early; in the less basic and less emotional aspects of society-than in their opposites; in the simple elements rather than in the complex ones; in form rather than in substance; and in elements that are acceptable to the culture rather than in strange elements.

    Furthermore, social change is easier if it is gradual. This is one reason why change has not come more quickly to Black Americans as compared to other American minorities, because of the sharp difference in appearance between them and white people.

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    Alaska's state fair, which runs until September 5^th, began as a celebration among residents of the Mantanuska Colony, a project under which 200 farm families were moved to Alaska to see whether agriculture could be possible in the coldest state. The state fair lives on, but little more than a decade after the start of the project most of the participants had abandoned their farms. The project was widely seen as a flop.

    In this state, glaciers cover 300 times more acres than farms. Only 5% of the food consumed is grown locally, compared with 81% nationwide. The growing season is short and summer temperatures chilly. Tomato plants wither(凋谢). Fruit trees, in most parts of the state, are just a dream.

    Enter the high tunnel: a greenhouse consisting of a metal frame with plastic stretched across it. Its few millimeters of plastic separate crops inside from the great outdoors. But this is enough for Alaskan growers to produce tomatoes as well as sweetcorn, peaches and kiwi fruit, and to boost production of crops by a quarter or more.

    In a place where no one blinks(眨眼) if you call yourself a fisherman, boat captain or gold miner, an increasing number of Alaskans are thinking of themselves as people who grow food. Since the start of the programme, the number of farms registered(登记)with the state has nearly doubled. Local restaurants have begun shaping their menus around what neighboring farms can grow.

    Eight decades ago, the Mantanuska Colony tried to turn farmers into Alaskans. Today, the high tunnels are turning Alaskans into farmers.

    If you want to slow aging, you might want to eat less. This finding is good news—if you were a mouse. The researchers studied mice, not people.

    John Price and other researchers studied two groups of mice. One group was able to eat as much as it wanted. The researchers limited what the mice in the other group ate. Their diet had 35 percent fewer calories than the first group of mice.

    Price says the mice with the diet restrictions were “more energetic and suffered fewer diseases.” They were not just living longer but seemed to stay younger for a longer period of time.

    The researchers found that fewer calories slow down a natural mechanism in cells called ribosomes. Price explains that ribosomes are responsible for making important proteins in the cells. But with fewer calories, they slow down. This gives the cells more time to repair themselves.

    The researchers say ribosomes use from 10 to 20 percent of the cell's energy to make those proteins. Price wrote that “because of this, it is impractical to destroy an entire ribosome” when it starts to break down. However, “repairing individual parts of the ribosome on a regular basis enables ribosomes to continue producing high quality proteins for longer than they would otherwise. This top quality production, in turn, keeps cells and the entire body functioning well.”

    Price said, “ribosome is a very complex machine, like a car.” They need “maintenance to replace the parts that wear out the fastest. When tires wear out,” he explained, “you don't throw the whole car away and buy a new one. It costs less to replace the old tires.”

    “Food,” he said, “isn't just material to be burned—it's a signal that tells our body and cells how to respond.” Price said the findings help to explain how exactly our bodies age. And this may “help us make more educated decisions about what we eat.”

    In today's Internet age, the demand for online games continues to grow. Online computer game centers exist in many cities and towns throughout Asia. Facing the pressures of school and life, people tend to the virtual（虚拟的）world, expecting a diversion from these problems. Too often, however, they can lead to problems and unhealthy addictions.

    This is most clearly seen in the example of South Korea. The country has the world's highest percentage of high-speed Internet services. It also has a high number of online game players and related problems. In 2002, a young man collapsed(突然晕倒) and died while playing online games. He had been playing almost non-stop for 86 hours at an Internet café. Another young man killed his sister after becoming confused between the online world and real life. A 12-year-old boy stole US $ 16,000 from his father and ran away from home. He did this to continue his obsession(着迷) with an online game. Such problems, however, don't just happen in South Korea. They are spreading to other parts of Asia as well.

    What kinds of people develop online game addiction? What does the problem look like? Dr. SueHuei Chen, a clinical psychologist, researches Internet addiction. She discovered some signs of at-risk individuals such as lack friendships and good social skills. Those problem individuals feel it so compulsive（强迫的）to play online games that they could sacrifice things such as school or family. They feel the need to spend more and more time online. And they become upset if anyone tries to limit their online game playing.

    How many problem game players are there? In mainland China, the potential number of problem online gamers is alarming. In 2004, the China daily reported that China had 13.8 million online game players. Besides, it stated that 80 percent of these were under 25 and had signs of addiction. Such numbers point toward a growing problem among Chinese youth.

    Make sure to keep control over your online game playing. If you don't control it, it can get control of you.

    We don't know how different our future will be in the future. We can only try to imagine it.

    At first we think about human relationship. In the year 2050, we will use computers almost every day. We will be making new friends through the Internet—even our husbands or wives will be met in this way. It will be much faster and easier for us. On the other hand, our relationships with people won't be as important as they are today—we will feel a little lonely.

    Computers will also help us in many other activities in 2050.For example, they will be used by the children at school to make their learning easier. In addition, there will be much more other machines which will play a similar role as computers, like robots which will do the housework for us.

    Spending holidays will also be completely different. Traveling to other planets or to the moon will be available for everyone. Means of transport will, of course, change, too. We will be using solar­powered cars, which will be much more environmentally friendly.

    We could expect that the faster technological progress would lead to a more polluted environment. But it isn't true. We will pay more attention to protecting the environment. And, scientists will probably find cures for many dangerous diseases, like cancer or AIDS. Therefore, our surroundings as well as health will be in better condition.

    Although we can't predict the exact changes which will be made in the world, we often think about them. We worry about our and our children's future; we have expectations, hopes as well as fears. But I think we should be rather optimistic about our future. We should be happy and believe good things will happen.

    From the earliest times, man has been interested in art. People have often worked together to collect and save the world's art treasures.

    Fine art treasures from many countries are kept in an art museum called the Louvre(卢浮宫)in Paris, France. The works of art have been collected by the people of France over many centuries.

    The Louvre has not always been a museum. The first building was a fort(炮台). In 1190, it was the king's castle with high walls and a round tower. It had a moat to keep out his enemies.

    Over the years, the number of buildings around the castle grew. By 1350, the castle was no longer needed as a fort. The Louvre became a palace home for French kings and queens.

    During times of peace, new treasures were brought in. During days of war, many treasures were stolen, and the buildings were damaged.

    When Francis Ⅰ became the king of France in 1515, he brought in artists from many countries. One of the artists was Leonardo da Vinci from Italy. Da Vinci's Mona Lisa is the best known painting in the museum today.

    In 1793, the Louvre became a public museum, just as it is now. It is a place where art treasures have been saved for everyone to enjoy.