It's a popular belief that a fish's memory lasts for only seven seconds. It may seem sad to think that they don't remember what they've eaten or where they've been, and they don't recognize you or any of their friends — every moment in their life would be like seeing the world for the first time.

    But don't be so quick to feel sorry for them. A new study has found that fish have a much better memory than we used to think. In fact, certain species of fish can even remember events from as long as 12 days ago.

    In the study, researchers from MacEwan University in Canada trained a kind of fish called African cichlids to go to a certain area of their tank to get food. They then waited for 12 days before putting them back in the tank again.

    Researchers used computer software to monitor the fish's movements. They found that after such a long break the fish still went to the same place where they first got food. This suggested that they could remember their past experiences.

    In fact, scientists had been thinking for a long time that African cichlids might have a good memory. An earlier study showed that they behaved aggressively（挑衅地） in front of certain fish, perhaps because they remembered their past “fights”. But until the latest findings, there was no clear evidence.

    Just as a good memory can make our lives easier, it also plays an important part when a fish is trying to survive in the wild.

    “If fish are able to remember that a certain area contains safe food, they will be able to go back to that area without putting their lives at risks,” lead researcher Trevor Hamilton told Live Science.

    For a long time, fish were placed far below chimpanzees, dolphins and mice on the list of smart animals. But this study has given scientists a new understanding of their intelligence.

    Kunta wondered why the white people had done this to him. Born a free man, he was now in chains. Heavy iron chains around his feet and hands were fixed to a metal bar that ran round the hall about ten centimeters off the ground. He was just able to lie down on the ground, but could not stand up.

    Kunta had been seized in the forest and then hit on the head with a hard object. When he woke up, his hands and feet had already been tied together. What shocked him most was that the men who carried him were black. He reasoned with them, and tried to persuade them to set him free. But they would not listen to him. When they came to the river, a white man was waiting in the boat for them. There was an argument about money, so it seemed, in a language that Kunta did not understand. Finally, Kunta was thrown into the bottom of the boat and covered with an old smelly cloth. The men took him in their boat to the castle on the coast where he was now held prisoner.

    Another thing which shocked Kunta was that women were held in the castle too. He could hear their crying, also children's voices. What was to become of them all, he wondered. For all his life, he had known that people suddenly disappeared from their villages. He had known that it was not safe to travel alone in the forest near the coast. But why did white people want to catch Africans and put them in chains? Would they be killed or even eaten? The situation seemed hopeless and he knew his life was in danger.

    Worse was to come. A few days later about 140 black people were taken and put on a tall sailing ship waiting off the coast. Once on the boat, they were taken below and their chains were fixed to two bars that ran the length of the ship. Their feet were fixed to one bar and their hands to another bar. Thus they lay on hard wooden boards, unable to stand up or move around.

    The sea journey lasted over sixty days and nights. They had rough weather and Kunta's back bled from rolling over on the hard wooden boards. Many of the men fell sick with fever. They sighed and cried out for more water, but food and water were only given out once a day. Once in a while sailors came down, Kunta thought, to carry sick men upstairs for treatment. When the ship finally arrived in a port, the wooden cover was opened wide and Kunta could see in daylight for the first time across the part of the ship where he had been chained. About a third of the people who had been chained up below at the beginning of the journey were missing.

    When you go to the doctor, you like to come away with a prescription．It makes you feel better to know you will get some medicine. But the doctor knows that medicine is not always needed. Sometimes all a sick person needs is some reassurance that all will be well. In such cases the doctor may prescribe a placebo.

    A placebo is a sugar pill, a harmless shot, or ail empty capsule. Even though they have no medicine in them, these things seem to make people well. The patient thinks it is medicine and begins to get better. How does this happen?

    The study of the placebo opens up new knowledge about the way the human body can heal itself. It is as if there was a doctor in each of us. The doctor will heal the body for us if we let it. But it is not yet known just how the placebo works to heal the body. Some people say it works because the human mind fools itself. These people say that if the mind is fooled into thinking it got medicine, then it will act as if it did, and the body will feel better.

    Placebos do not always work. The success of this treatment seems to rest a lot with the relationship between the patient and the doctor. If the patient has a lot of trust in the doctor and if the doctor really wants to help the patient, then the placebo is more likely to work. So in a way, the doctor is the most powerful placebo of all.

    A placebo can also have bad effects. If patients expect a bad reaction to medicine, then they will also show a bad reaction to the placebo. This would seem to show that a lot of how you react to medicine is in your mind rather than in your body. Some doctors still think that if the placebo can have bad effects it should never be used. They think there is still not enough known about it.

    The strange power of the placebo does seem to suggest that the human mind is stronger than we think it is. There are people who say you can heal your body by using your mind. And the interesting thing is that even people who swear this is not possible have been healed by a placebo．

    Learning to speak English well may be the best thing you can do to improve your life. That's right. If you can communicate in English, you can do the following things:

    Contact (联系) people from all over the world. Talk about your ideas and opinions on Internet discussion groups. Send e-mails to interesting people. Learn about their life and culture.

    Travel more easily. Communicate with people wherever you go—English is spoken in more than 100 countries. Ask directions, have a conversation, or ask for help. Maybe English will save your life some day!

    Push your career forward. If you want a good job in business, technology, or science, get out of that armchair and start learning English now! If you already have a good job, start learning before you lose it! Knowing English will let you do the following things:

    Put “excellent knowledge of English” on your CV (履历). Get your dream job, and earn more money.

    Gain technical knowledge. English is the language of technology, especially high technology like computer science, and medicine. If you're going to read about technology, you'll probably have to do it in English.

    Be a world-class businessman or woman. It's simple. International business is done in English. And all business today is international. So if you want to play, you have to know English—to contact other business people, go to conferences, and read international business newspapers and magazines, ect.

    Become a better scientist. Contact scientists from other countries, go to international conferences, and visit research centers abroad. Learn about new scientific discoveries by reading papers, books, and magazines.

    Use your computer more effectively. Most computer applications are in English, so you will understand them better—and become a better employee.

    When something goes wrong, it can be very satisfying to say, “Well, it's so-and-so's fault.” or “I know I'm late, but it's not my fault; the car broke down.” It is probably not your fault, but once you form the habit of blaming somebody or something else for a bad situation, you are a loser. You have no power and could do nothing that helps change the situation. However, you can have great power over what happens to you if you stop focusing on whom to blame and start focusing on how to remedy the situation. This is the winner's key to success.

    Winners are great at overcoming problems. For example, if you were late because your car broke down, maybe you need to have your car examined more regularly. Or, you might start to carry along with you the useful phone numbers, so you could call for help when in need. For another example, if your colleague causes you problems on the job for lack of responsibility or ability, find ways of dealing with his irresponsibility or inability rather than simply blame the person. Ask to work with a different person, or don't rely on the person. You should accept that the person. Ask to work with a different person, or don't rely on this person. You should accept that the person is not reliable and find creative ways to work successfully regardless of how your colleague fails to do his job well.

    This is what being a winner is all about—creatively using your skills and talents so that you are successful no matter what happens. Winners don't have fewer problems in their lives; they have just as many difficult situations to face as anybody else. They are just better at seeing those problems as challenges and opportunities to develop their own talents. So, stop focusing on “whose fault it is.” Once you are confident about your power over bad situations, problems are just stepping stop on for success.

    Global warming is the process of earth's atmosphere heating up. Over the last 100 years, the average temperature of earth's atmosphere has gone up 1 Fahrenheit. The weather has not changed exactly the same way in every area of the planet. But scientists think that the rise in average temperature is already affecting the earth, s climate.

    Many scientists now believe that global warming is caused by cutting down trees, producing more trash, and polluting the environment are some of the reasons that the temperature has gone up. Many scientists believe that the biggest causes of global warming are new human technologies that release greenhouse gases into the atmosphere.

    The greenhouse effect is not new. Certain gases in the atmosphere, like carbon dioxide, nitrous oxide and methane, prevent heat energy from escaping back into space. In the past, the climate didn't change much because nature produced just the right amount of greenhouse gases to deal with it.

    Today, most scientists are pretty sure that the rising temperature can't be blamed on nature. Ever since the industrial revolution in the 1700s, humans have relied on machines for daily life. And many of those machines give off a lot of greenhouse gases. An increase in the release of greenhouse gases from human activities is throwing nature off balance.

    The climate is a very complicated thing, but many scientists agree that the rising atmospheric temperature has already damaged the environment. Sheets of ice, called glaciers, are melting in Antarctica and other parts of the globe. As glaciers break off and melt into the oceans, they are adding warm water to the oceans and causing the sea level to rise.

    Over the past last 100 years, the sea level has risen 6-8 inches around the world. That means land along the coasts is beginning to disappear under water. Bigger and warmer oceans are also adding to other weather problems caused by pollution in the atmosphere. Some places have received more rain, others have had bigger storms and a few areas in the world have experienced unusual droughts.