Think about the different ways that people use the wind. You can use it to fly a kite or to sail a boat. Wind is one of our cleanest and richest power sources, as well as one of the oldest. Evidence shows that windmills(风车) began to be used in ancient Iran back in the 7th century BC. They were first introduced to Europe during the 1100s, when armies returned from the Middle East with knowledge of using wind power.

    For many centuries, people used windmills to grind(磨碎) wheat into flour or pump water from deep underground. When electricity was discovered in the late 1800s, people living in remote(偏远的) areas began to use them to produce electricity. This allowed them to have electric lights and radio. However, by the 1940s when electricity was available(可利用的) to people in almost all areas of the United States, windmills were seldom used.

    During the 1970s, people started becoming concerned about the pollution that is created when coal and gas are burned to produce electricity. People also realized that the supply of coal and gas would not last forever. Then, wind was rediscovered, though it means higher costs. Today, there is a global movement to supply more and more of our electricity through the use of wind.

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The baby monkey is much more developed at birth than the human baby. Almost from the moment it is born, the baby monkey can move around and hold tightly to its mother. During the first few days of its life the baby will approach and hold onto almost any large, warm, and soft object in its environment, particularly if that object also gives it milk. After a week or so, however, the baby monkey begins to avoid newcomers and focuses its attentions on “mother” — the real mother or the mother-substitute(母亲替代物）.

During the first two weeks of its warmth is perhaps the most important psychological（心理的） thing that a monkey mother has to give to its baby. The Harlows, a couple who are both psychologists, discovered this fact by offering baby monkeys a choice of two types of mother-substitutes — one covered with cloth and one made of bare wire. If the two artificial mothers were both the same temperature, the little monkeys always preferred the cloth mother. However, if the wire model was heated, while the cloth model was cool, for the first two weeks after birth the baby monkeys picked the warm wire mother-substitutes as their favorites. Thereafter they switched and spent most of their time on the more comfortable cloth mother

    Why is cloth preferable to bare wire? Something that the Harlows called contact（接触的） comfort seems to be the answer, and a most powerful influence it is. Baby monkeys spend much of their time rubbing against their mothers' skins, putting themselves in as close contact with the parent as they can. Whenever the young animal is frightened, disturbed, or annoyed, it typically rushes to its mother and rubs itself against her body. Wire doesn't“rub”as well as does soft wire cloth. Prolonged（长时间的）“contact comfort” with a cloth mother appears to give the babies confidence and is much more rewarding to them than is either warmth or milk.

    According to the Harlows, the basic quality of a baby's love for its mother is trust. If the baby is put into an unfamiliar playroom without its mother, the baby ignores the toys no matter how interesting they might be. It screams in terror and curls up into a fury little ball. If its cloth mother is now introduced into the playroom, the bay rushes to it and holds onto it for dear life. After a few minutes of contact comfort, it obviously begins to feel more secure. It then climbs down from the mother-substitute and begins to explore the toys, but often rushes back for a deep embrace（拥抱）as if to make sure that its mother is still there and that all is well. Bit by bit its fears of the new environment are gone and it spends more and more time playing with the toys and less and less time holding on to its “mother.”

    All over the world people enjoy sports. Sports help to keep people healthy, happy and help them to live longer.

    Sports change with the season. People play different games in winter and summer.

    Games and sports often grow out of people's work and everyday activities. The Arabs use horses or camels in much of their everyday life; they use them in their sports, too.

    Some sports are so interesting that people everywhere go in for them. Football, for example, has spread around the world. Swimming is popular in all countries near the sea or in those with many rivers.

    Some sports or games go back to thousands of years, like running or jumping. Chinese boxing, for example, has a very long history. But basketball and volleyball are rather new. Neither one is a hundred years old yet. People are inventing new sports or games all the time.

    People from different countries may not be able to understand each other, but after a game they often become good friends. Sports help to train a person's character(性格). One learns to fight hard but fight fair, to win without pride and to lose with grace(体面).

    As a capital city full of art and history, London is an important political centre and a huge financial marketplace. Whatever you think about London, visiting as a tourist is very different from living there. Each part of London has its own character. Some parts are richer than others, or more industrial, or have better housing.

    Let's start with the centre, the “Square Mile”. This is the oldest part of London. In the past, it was where all financial business was done. Not many people live here, but 300,000 people work here every day.

    Moving west, we come to the West End. This busy shopping and entertainment district is bursting with things to do. Take a walk down Oxford Street, and you will see big department stores like Selfridges and Harrods. Rents here are very high; a one-bedroom apartment may cost around 1,000 pounds a week. Further away is West London. This area is more residential(住宅的)and very fashionable.

    The East End contains the Port of London, which historically is where many immigrants first arrived. Waves of French, Belgians, Jews, Pakistanis and Bangladeshis have all lived here. This makes the culture of this area very various. London won the bid to hold the Olympics in 2012, so many Londoners hope that housing, education and employment for many people in this area will improve.

    It is difficult to be general about London. The city is made up of a " collection of villages”, each area with its own character and community. Put them all together, and you have London, an international capital.

Both humans and animals have enemies. 11 is easy for us to know the difference between our friends and our enemies. But can other animals do the same? Elephants can! They can use their sense of vision and smell to tell the difference between people who mean a threat and those who do not. In Kenya, researchers find that elephants react differently to clothing worn by men of the Maasai and Kamba ethnic groups. Young Maasai men hunt animals and thus mean a threat to elephants; Kamba men are mainly farmers and are not a danger to elephants.

In an experiment conducted by animal scientists, elephants were first presented with clean clothing or clothing that had been worn for five days by either a Maasai or a Kamba man. When the elephants noticed the smell of clothing worn by a Maasai man, they moved away from the smell faster and took longer to relax than when they noticed the smells of either clean clothing or clothing worn by a Kamba man.

Clothing color also plays a role. In the same study, when the elephants saw red clothing not worn before, they reacted angrily, as red is typically worn by Maasai men. Rather than running away as they did with the smell, the elephants acted angrily toward the red clothing.

The researchers believe that the elephants' emotional reactions arc due to their different senses of smell and sight. Smelling a possible danger means that a threat is nearby and the best thing to do is run away and hide. Seeing a potential threat without its smell means that risk is low. Therefore, instead of showing fear and running away, the elephants express their anger and become aggressive.

    In the classic marriage vow (誓约), couples promise to stay together in sickness and in health. But a new study finds that the risk of divorce among older couples rises when the wife－not the husband－becomes seriously ill.

    "Married women diagnosed with a serious health condition may find themselves struggling with the impact of their disease while also experiencing the stress of divorce." said researched Amelia Karraker.

    Karraker and co-author Kenzie Latham analyzed 20 years of data on 2,717 marriages from a study conducted by Indiana University since 1992. At the time of the first interview, at least one of the partners was over the age of 50.

    The researchers examined how the onset (发生) of four serious physical illnesses affected marriages. They found that, overall, 31% of marriages ended in divorce over the period studied. The incidence of new chronic (慢性的) illness onset increased over time as well, with more husbands than wives developing serious health problems.

    "We found that women are doubly weak when their marriage breaks up in the face of illness," Karraker said. "They're more likely to be widowed, and if they're the ones who become ill, they're more likely to get divorced."

    While the study didn't assess why divorce is more likely when wives but not husbands become seriously ill, Karraker offers a few possible reasons. "Gender roles and social expectations about caregiving may make it more difficult for men to provide care to sick spouses." Karraker said. "And because of the imbalance in marriage markets, especially in older ages, divorced men have more choices among potential partners than divorced women."

    Given the increasing concern about health care costs for the aging population, Karraker believes policymakers should be aware of the relationship between disease and risk of divorce.

    "Offering support services to spouses caring for their other halves may reduce martial stress and prevent divorce at older ages." she said. "But it's also important to recognize that the pressure to divorce may be health-related and that sick ex-wives may need additional care and services to prevent worsening health and increased health costs."