When the population of the port town began to suffer from poisoning, the police came to find the cause of the poison. They thought someone was poisoning the people on purpose but no one knew how it was possible. Soon people took the position that the pork was poisoned. It was a popular food everyone ate and it could have possibly made everyone sick. Anyone who had possession of pork would throw it out. Even the poorest of the poor wouldn't eat pork. Signs were posted on poles and letters were sent to everyone to warn people of the pork. Shortly afterwards, even policemen in high positions were also getting sick.

    Soon it became political and popular. Politicians rushed to the town to talk about politics and promised how they would find the solution if they were elected. Everyone was so sick that they didn't care about politics. Everyone was in a position where he or she didn't know what to do anymore. They went to the post office to mail posts out asking for help. The poor town didn't know how to deal with the situation.

    One day, a well-known scientist from New York came to the town with a huge box containing many instruments and his possessions. He went to pools and the port and made measurements. He was quiet and polite. Then one day he made a speech at a newspaper meeting-room to announce his findings.

    “I'm sorry to say your water supply is so heavily polluted; it is poisoned. I know who has been poisoning you all for such a long time. It is you who have been poisoning yourselves with pollution. A great deal of rubbish has been thrown into the water day after day. No one here has taken good care of the environment. It is no wonder all of you have been sick.” Shocked at the news, the people present were lost in thought.

    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.

    Some of the best research on daily experience is rooted in rates of positive and negative interactions, which has proved that being blindly positive or negative can cause others to be frustrated or annoyed or to simply tune out.

    Over the last two decades, scientists have made remarkable predictions simply by watching people interact with one another and then scoring the conversations based on the rate of positive and negative interactions. Researchers have used the findings to predict everything from the likelihood that a couple will divorce to the chances of a work team with high customer satisfaction and productivity levels.

    More recent research helps explain why these brief exchanges matter so much. When you experience negative emotions as a result of criticism or rejection, for example, your body produces higher levels of the stress hormone, which shuts down much of your thinking and activates (激活) conflict and defense mechanisms (机制). You assume that situations are worse than they actually are.

    When you experience a positive interaction, it activates a very different response. Positive exchanges increase your body's production of oxytocin, a feel-good that increases your ability to communicate with, cooperate with and trust others. But the effects of a positive occurrence are less dramatic and lasting than they are for a negative one.

    We need at least three to five positive interactions to outweigh every one negative exchange. Bad moments simply outweigh good ones. Whether you're having a conversation, keep this simple short cut in mind: At least 80 percent of your conversations should be focused on what's going right.

    Workplaces, for example, often see this. During performance reviews, managers routinely spend 80 percent of their time on weaknesses and “areas for improvement”. They spend roughly 20 percent of the time on strengths and positive aspects. Any time you have discussions with a person or group, spend the vast majority of the time talking about what is working, and use the remaining time to address weaknesses.

    The Children's Groundwater Festival, first organized by the Groundwater Foundation 19 years ago, is celebrated every year in Nebraska, a state of the central United States in the Great Plains. After organizing the festival for 16 years, the foundation passed the program on to the local community of Grand Island, Nebraska. The festival is an annual event for fourth and fifth graders of Nebraska. It is an interesting and energetic day filled with hands­on education. Water magic, folk singers and musicians, storytellers, and bird shows add to the happy atmosphere during the festival. There are also some educational activities:

    Gooey Garbage: Children build a landfill (废物填埋场) and learn how a properly­built landfill can protect groundwater.

    Water Races: Children learn about water pollution by racing a drop of water through a model.

    Well in a Cup: By building a small aquifer (蓄水层) in a cup, children learn about aquifers and drinking water wells.

    Taster's Choice: Children drink different types of water, from tap water to bottled water. Then they are taught about the treatment process of each type of water.

    There's No New Water: Students are taught to make a special glass container and learn about the water cycle.

    The Children's Groundwater Festival not only has a great influence on Nebraska's people. So far, similar festivals have been held in nearly 40 American states, Mexico City, several provinces in Canada, and New Delhi, India. People everywhere are realizing the importance of educating young people to learn and care about groundwater.

    For more information about this festival, remember to watch our program tomorrow evening. I'll be waiting for you.

    Before the 1830s, most newspapers were sold through annual subscriptions in America, usually $8 to $10 a year. Today $8 or $10 seems a small amount of money, but at that time these amounts were forbidding to most citizens. Accordingly, newspapers were read almost only by rich people in politics or the trades. In addition, most newspapers had little in them that would appeal to a mass audience. They were dull and visually forbidding. But the revolution that was taking place in the 1830s would change all that.

    The trend, then, was toward the "penny paper" ­a term referring to papers made widely available to the public. It meant any inexpensive newspaper; perhaps more importantly it meant newspapers that could be bought in single copies on the street.

    This development did not take place overnight. It had been possible(but not easy)to buy single copies of newspapers before 1830, but this usually meant the reader had to go down to the printer's office to purchase a copy. Street sales were almost unknown. However, within a few years, street sales of newspapers would be commonplace in eastern cities. At first the price of single copies was seldom a penny­usually two or three cents was charged­and some of the older well­known papers charged five or six cents. But the phrase "penny paper" caught the public's fancy, and soon there would be papers that did indeed sell for only a penny.

    This new trend of newspapers for "the man on the street" did not begin well. Some of the early ventures(企业)were immediate failures. Publishers already in business, people who were owners of successful papers, had little desire to change the tradition. It took a few youthful and daring businessmen to get the ball rolling.

    If you ask most people what water tastes like, they'll probably tell you that water has no taste and they may give you a funny look. But if you were a fruit fly, asking another fruit fly, that question might have a different answer.

    To a fruit fly, water has a taste. Scientists want to know how the fruit fly knows water because this information may help in learning how other animals — or even individual cells — manage to use water in the right way. Water is vital to life, but too much or too little can be deadly to a living creature. So by understanding how the fruit fly tastes water, researchers may learn more about other living things.

    According to the new study, a protein(蛋白质) called PPK28 makes it possible for a fly to taste water. Proteins build cells and tissues, fight disease and carry messages between cells. It's not surprising that a protein is responsible for the fruit fly's ability to taste water.

    The PPK28 protein is part of a larger family of similar proteins. One of these related proteins is used by mammals (including humans) to taste salt. Scientists have not found a protein that enables humans to "taste" water.

    In the experiment, Cameron and his team compared normal fruit flies with fruit flies whose taste cells had been disabled. The fruit flies were given a special chemical that would glow(发光) when the fly used the PPK28 protein. Then the scientists led the flies to water. When the normal flies tasted the water, the PPK28 protein lit up — showing that it was in use.

    The fruit fly in particular is so interesting that some scientists are hard at work creating a complete map of the fruit fly brain. This map will show all of a fly's neurons and help scientists understand how the neurons work together.