No one knows for sure when advertising first started. It is possible that it grew out of the discovery that some people did certain kinds of work better than others did them. That led to the concept of specialization, which means that people would specialize, or focus, on doing one specific job.

    Let's take a man we'll call Mr. Fielder, for example. He did everything connected with farming. He planted seeds, tended the fields, and harvested and sold his crops. At the same time, he did many other jobs on the farm. However, he didn't make the bricks for his house, grind the wheat for his flour, or cut his trees into boards. He also did not make the plows(犁), the work boots, or any of the other hundreds of things a farm needs. Instead, he got them from people who specialized in doing each of those things.

    Suppose there was another man we shall call Mr. Plowright. Using what he knew about farming and working with iron, Mr. Plowright invented a plow that made farming easier. Mr. Plowright did not really like farming himself and wanted to specialize in making really good  plows. Perhaps, he thought, other farmers will trade what they grow for one of my plows.

    How did Mr. Plowright let people know what he was doing? Why, he advertised, of course. First he opened a shop and then he put up a sign outside the shop to attract customers. That sign may have been no more than a plow carved into a piece of wood and a simple arrow pointing to the shop door. It was probably all the information people needed to find Mr. Plowright and his really good plows.

    Many historians believe that the first outdoor signs were used about five thousand years ago. Even before most people could read, they understood such signs. Shopkeepers would carve into stone, clay, or wood symbols for the products they had for sale.

    A medium, in advertising talk, is the way you communicate your message. You might say that the first medium used in advertising was signs with symbols. The second medium was audio, or sound, although that term is not used exactly in the way we use it today. Originally, just the human voice and maybe some kind of simple instrument, such as a bell, were used to get people's attention.

    A crier, in the historical sense, is not someone who weeps easily. It is someone, probably a man, with a voice loud enough to be heard over the other noises of a city. In ancient Egypt, shopkeepers might hire such a person to spread the news about their products. Often this primitive form of advertising involved a newly arrived ship loaded with goods. Perhaps the crier described the goods, explained where they came from, and praised their quality. His job was, in other words, not too different from a TV or radio commercial in today's world.

    Daylight-powered germ-killing equipment（杀菌设备）may someday help protect health workers from deadly virus like Ebola virus. That is a finding from a study published in the journal Science Advances.

    Study organizers say they've developed membranes（薄膜）that produce very small amounts of hydrogen peroxide（过氧化氢）when left in daylight. Membranes are thin plastic, structures that can serve as barriers. They let some things pass through, but other things art blocked. Hydrogen peroxide, a liquid sold in drug stores, works as a disinfectant（杀菌剂）.

    Nearly 500 health workers were infected and died in 2014 when Ebola spread through parts of West Africa. Caregivers wear full-body protective suits when they come into contact with patients with infectious diseases. But the process of removing the suits is a time when infection can spread if the surface is covered with virus. “If there's any live bacteria or virus on the surface, it's still transmissible and could cause infection,” said Gang Sun of the University of California. He is one of the researchers that worked to develop membranes that could cover the outside of protective equipment.

    When the chemical molecules（分子）on the surface of these membranes are put in sunlight, they react with oxygen in the air to produce small amounts of hydrogen peroxide. Gang Sun explains that the process creates less hydrogen peroxide than what you would use to remove dirt on clothing, for example. But it is still enough to kill organisms.

    Rohan Tikekar is a food scientist with the University of Maryland. He described the development as “quite novel,” or new and different, Tikekar was not involved with the recent study. He said others have developed materials that produce disinfecting chemicals. But most only work under high-energy ultraviolet（U V）light, and not usual daylight. The new membrane also works in the dark for at least an hour or two because of chemical properties that can recharge its germ-killing powers. Tikekar called that an important improvement.

    Gang Sun said the new membranes, though still Far from perfect could be used for things other than protective equipment for health workers. They could also be added to packaging for fruits and vegetables to keep foods fresher and reduce the risk of being polluted. Some versions of the material use natural chemicals' Sun says that one of the next steps is to make it safe to sat

    When school started on that warm August day, I threw myself into everything I did, including playing volleyball. I decided to become beautiful, or at the very least, skinny. I stopped eating completely. Soon I began losing weight, which thrilled me, and I even grew to love the tiredness and lightheadedness( 头晕)that came with my poor diet, for those feelings meant that I was winning.

    As the season progressed, things had become tense between my head volleyball coach, Coach Smith, and me. She felt that something was wrong with my health. She talked with me about my eating and was angry that I wouldn't listen to her when she tried to make me eat. She tried to persuade me in a determined way and so we fought constantly. Then my hunger started to affect my performance. I was so tired that practice and games were becoming a struggle. One afternoon, with hurt in her eyes, Coach Smith asked me what I had eaten and I told her nothing yet. She looked at me, disappointment in her eyes, knowing she couldn't make me stop, and walked away.

    A couple of weeks later I attended a formal dinner for our volleyball team. I stood there as my coach managed to say something nice about me. I realized then that I had ruined my senior year by being disrespectful, and I had probably ruined hers as well. So that evening I wrote her a letter apologizing and thanking her.

    Then one Saturday, as I was reading in the library, I felt someone gently take my arm and say softly, “Lynn Jones, how are you doing?” I looked up and saw the familiar face. “Thanks for the letter,” she said. “It meant a lot.” When I think of a coach, I think of someone above me, someone who gives instruction — not a friend. But Coach Smith is different, and, like any other good friend, she dealt with my problem in a determined way even when I hated her for it at that time. I didn't deserve her kindness, but she gave it anyway. I will forever be grateful for her help, and now for her friendship.

    My favourite book is The Adventure of Tom Sawyer by Mark Twain. Tom lives with his aunt Polly in a quiet street of St. Petersburg, Missouri. He's a lively and clever young boy, and he finds himself in many exciting adventures. He runs away with his two friends, Huck Finn and Joe, to an island in the middle of the Mississippi River for several days. With Huck he goes looking for treasure, with Becky he gets lost in a cave. And finally, they find a box of gold.

    My favourite scene in the book is when everyone thinks Tom is dead. He decides to go to his own funeral. He hides and watches for a time and then suddenly he appears. Everyone is astonished to see him but they're also pleased to see him alive.

    Tom is the hero of the story, but there are other important characters. Huck is an outsider and everyone is afraid of him. Becky is pretty with fair hair, Joe is Tom's best friend. And Injun Joe is the bad man of the story.

    The theme of the story is about children growing up. It describes how strangers are seen in small towns of America. Finally, it talks about freedom, social rules and how people are punished for bad behaviour.

    Why do I think The Adventure of Tom Sawyer is a great book? Mark Twain wrote the story in 1876, but it's still read and loved by people all over the world today. And although it's only a story, Twain wrote it in the everyday English of the southern states of America in the 19th century, so it sounds very real. Today it's thought to be one of the greatest books in American literature. Go on—read it! I know you'll enjoy it, too.

    With all the recent concern about the environment, people want to see their money used to better the planet. Here are four well-known environmental organizations.

    World Wildlife Fund (WWF)

    The World Wildlife Fund is perhaps one of the best-known organizations for the protection of endangered species and their habitats around the world. They've been around for over 45 years. You can donate through their website worldwildlife.org, join their organization as a member, or adopt an animal through their online adoption center.

    National Geographic Society (NGS)

    National Geographic Society is well-known for their magazine and their specials on TV. The organization itself is one of the longest-running in the world—they've been around since 1888, focus on exploration and conservation of forests, oceans, habitats, species and societies. You chopse to donate through the website nationalgeographic.com，buy something at their online store, or order a magazine subscription.

    National Wildlife Federation (NWF)

Founded officially in 1937, the National Wildlife Federation tries to protect wildlife at all costs. In fact, they believe that having the public educated is the best way to help the environment—the more you know, the more you can protect the world we live in. Donations to the NWF can be made through their website nwf. org or through other options, like matching gifts, workplace giving, or memorial donations.

    Ecology Fund, com

    Set up in 1976，Ecology Fund, com is run on user clicks. Advertisers buy ad space on the site every time someone clicks. The money goes to buy endangered wilderness land to protect it from companies that would destroy it. So far, Ecology Fund, com has bought land in many areas. The best thing about this site is that you needn't donate any money—all you have to do is click.

Throughout our daily lives, we have known plenty of people and will know more. But how can we tell if someone is worth our trust? In a paper published recently in the Journal of Personality and Social Psychology, researcher gave us the answer.

The researchers asked 401 adults from the United States to fill out a questionnaire measuring their guilt-proneness (内疚倾向) in different situations as well as several other qualities, and then play a short online game. In this game, Player 1 is given 1, which they can choose to give to Player 2. Any money given to Player 2 is then automatically increased to 2.50. Player 2 can then decide whether to keep all of the money or behave in a trustworthy way by returning a part of the money to Player 1. The researchers found more guilt-prone people were more likely to share the money with Player 1. Actually, in follow-up studies, guilt-proneness predicted trustworthiness better than other personality qualities the researchers measured.

Why might guilt lead to trustworthy behavior? The researchers found people who were guilt-prone also reported feeling a must to act in ethical (合乎道德的) and responsible ways while interacting (互动) with their partners in the game. People who are guilt-prone tend to avoid engaging in behavior that might harm or disappoint others. If they do something bad, guilt encourages them to try to make things right again.

Then, how can we use this research to ascertain whether someone is trustworthy? "One way to do this might be observe how they respond to experience regret," lead author Emma Levine, assistant professor at the University of Chicago Levine, explains. Another way is to ask them to describe a difficult dilemma they faced in the past, suggests co-author Taya Cohen, associate professor at Carnegie Mellon University. This is particularly effective, Cohen and her colleagues have found, because it allows us to see if they're concerted about the effects their actions have on others.