Everyone has got two personalities (性格)—the one that is shown to the world and the other that is secret and real. You don't show your secret personality when you're awake because you can control yourself, but when you're asleep, your sleeping position shows the real you. In a normal night, of course, you often change your sleeping positions. The important position that best shows your secret personality is the one that you go to sleep.

    If you go to sleep on your back, you're a very open person. You normally trust people and you are easily influenced by new ideas. You don't like to make people unhappy, so you never express your real feelings. You're quite shy and you aren't very confident.

    If you sleep on your stomach, you are a person who likes to keep secrets. You worry a lot and you're always easily becoming sad. You never want to change your ideas, but you are satisfied with your life the way it is. You usually live for today not for tomorrow.

    If you sleep on curled up (蜷缩) , you are probably a very nervous person. You have a low opinion of yourself and often protect yourself from being hurt, so you are very defensive. You're shy and you don't usually like meeting people. You like to be on your own.

    If you sleep on your side, you have usually got a well-balanced (平衡的) personality. You know your strengths and weaknesses. You're usually careful. You have a confident personality. You sometimes feel worried, but you don't often get unhappy. You always say what you think, even if it makes people angry.

    We know the mosquito very well. Mosquitoes fly everywhere. They can be found almost all over the world， and there are more than 2，500 kinds of them.

    No one likes the mosquito. But the mosquito may decide that she loves you. She？ Yes，she. It's true that male mosquito doesn't bite（咬） and only the female mosquito bites because she needs blood to lay eggs. She is always looking for things or people she wants to bite. If she likes what she finds， she bites. But if she doesn't like your blood，she will turn to someone else for more delicious blood. Next time a mosquito bites you，just remember you are chosen. You're different from the others！

    If the mosquito likes you，she lands on your body without letting you know. She bites you so quickly and quietly that you may not feel anything different. After she bites，you will have an itch（痒） on your body because she puts something from her mouth together with your blood. By the time the itching begins，and she has flown away.

    And then what happens？ Well，after her delicious dinner，the mosquito feels tired. She just wants to find a place to have a good rest. There，on a leaf or a wall， she begins to lay eggs，hundreds of eggs.

    Is there intelligent (有智力的) life on other planets? For years, scientists said "no" or "we don't know". But today this is changing. Seth Shostak and Alexandra Barnett are astronomers (天文学家). They believe intelligent life exists (存在) somewhere in the universe. They also think we will soon contact these beings (人；生物).

    Why do Shostak and Barnett think intelligent life exists on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old. "This is long enough for other planets to have intelligent life," say Shostak and Barnett. The second reason is size—the universe is huge. "Tools like the Hubble Telescope (哈勃望远镜) have shown that there are at least 100 billion galaxies," says Shostak. "And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be similar to Earth."

    In the past, it was hard to look for signs of intelligent life in the universe. But now, powerful telescopes (高倍望远镜) allow scientists to discover smaller planets. These planets might have intelligent life.

    Have beings from space already visited Earth? "Probably not," says Shostak. However, intelligent beings may contact us in other way, such as radio signals (信号). In fact, they may be trying to communicate with us now, but we don't have the right tools to receive their messages. However, this is changing. By 2025, we could make contact with other life forms in our universe and we might help each other.

    November 5 is World Tsunami(海啸) Awareness Day. Tsunami is a Japanese word for a long, destructive(摧毁性的) ocean wave caused by an undersea earthquake. The goal of the anniversary is to learn from disasters(灾害) of the past and to prepare for the future. Two tsunamis in the last 15 years have changed the way people around the world think about these destructive events.

    On December26, 2004, a magnitude (震级) 9 earthquake near the coast of Indonesia caused tsunami waves that struck the coasts of four countries. An estimated(估计的) 230,000 people died and costs were in the billions of dollars. Then, on March 11, 2011, a magnitude 9 earthquake struck northeastern Japan. It was the most powerful earthquake ever recorded in that country. More than18,000 people died. The tsunami also caused serious damage to the Fukushima Daiichi nuclear power center on the island of Honshu. Several nuclear reactors(核 反应堆) were severely(严重地) damaged and leaked(泄漏) radiation(辐射).

    The two events caused people in the Pacific and Indian Ocean areas to study and improve preparedness for disasters. This led to the SendaiFrameworkfor DisasterRiskReductionin 2015 in Sendai, Japan. The agreement was a UN effort to raise awareness(提高意识) about disaster risks and to urge(催促) countries to assess(评估)how well they were prepared for them.

    Willem Rampangilei is head of the Disaster Management Agency in Indonesia. He said Indonesia passed a law on disaster management after the 2004 tsunami. It led in 2008 to the creation of his agency. "Our responsibilities include reduction and preparedness, emergency response, as well as post-disaster recovery and reconstruction(重新建设)," he said. He added that 150 million Indonesians were at risk from earthquakes, 60 million from floods and four million from tsunamis.

    Preparedness has spread beyond Asia. There are now early warning systems in place for the Caribbean Sea, the Northeast Atlantic Ocean, the Mediterranean Sea and surrounding(周围的) areas.

    Some students get so nervous before an exam that they do poorly even if they know the material. Sian Beilock, a psychology (心理学) professor at the University of Chicago, has studied these highly anxious (焦虑的) exam-takers.

    "They start worrying about the results. They might even start worrying about whether this exam is going to prevent them from getting into the college they want. And when we worry, it actually uses up attention and memory resources that we could otherwise be using to focus (集中) on the exam." says Sian Beilock.

    The researchers tested the idea on a group of twenty anxious college students. They gave them two short math tests. After the first one, they asked the students to either sit quietly or write about their feelings about the coming second test.

    The researchers added to the pressure. They told the students that those who did well on the second exam would get money. They also told them that their performance would affect other students as part of a team effort.

    Professor Beilock says those who sat quietly scored an average of 20% worse on the second exam. But the students who had written about their fears improved their performance by an average of 5%.

    Next, the researchers used younger students in a biology class. They told them before final exams either to write about their feelings or to think about things not connected to the test.

    Professor Beilock says highly anxious students who wrote about their feelings got an average grade of B＋, compared with a B—for those who did not.

    But what can they do if students do not have a chance to write about their fears immediately before an exam or presentation? Professor Beilock says students can try it themselves at home or in the library and they can still improve their performance.

    Many people say dolphins are very itelligent. They seem to be able to think, understand, and learn things quickly. But are they smart like humans or are they more like cats or dogs? Dolphins use their brains differently from people. But scientists say dolphin intelligence and human intelligence are similar in some ways. How?

    Like humans, every dolphin has its own name. The name is a special whistle. Each dolphin chooses a specific whistle for itself, usually by its first birthday. Actually, scientists think dolphins, like people, "talk" to each other about a lot of things, such as their age, their feelings, or finding food. And, like humans, dolphins use a system of sounds and body language to communicate. But understanding their conversations is not easy for humans. No one speaks "dolphin" yet, but some scientists are trying to learn.

    Dolphins are also social animals. They live in groups, and they often join others from different groups to play games and have fun—just like people. In fact, playing together is something only intelligent animals do.

    Dolphins and humans are similar in another way: both species make plans to get something they want. In the seas of southern Brazil, for example, dolphins use an interesting strategy to get food. When fish are near a boat, dolphins show signs to the fishermen to put their nets in the water. Using this method, the men can catch a lot of fish. What is the advantage for the dolphins in doing so? They get to eat some of the fish that escape from the net.

    You are visiting the Eiffel Tower in France, but the next second you are in Thailand. Then, suddenly you may have dinner with Barack Obama in America. But you are not dreaming. This is what might happen in the near future. With the help of virtual reality(Vr,虚拟现实) technology, lots of changes are taking place in our life.

    VR is a computer technology that makes an environment and allows users to see and even interact with it. Just wear a pair of VR glasses joined to your computer and you can experience a lot of things without stepping out of your room. "The most interesting part of virtual reality is that it offers an immersive(身临其境的)experience," said Wang Bing, leader ,leader of the Chinese entertainment company Funshow.  "That's why VR movies are popular among users. You become a part of the story. "According to the Report on Chinese VR Users' Behaviour last month, over 960, 000 people in China have bought VR products and 83. 2 percent of them have watched VR movies.

    VR can also be used in some other ways. It can help to train workers before they have to work in highly dangerous environments. VR also helps patients with acrophobia(恐高症) by making them think they are standing on the top of a tall building.

    However, VR technology still has a long way to go. Users report feeling sick while wearing VR glasses. Maybe it could take a period of time for VR to be widely used around the world.

    Have you ever stayed in a hotel? Most Chinese hotels often provide guests with things like disposable(一次性的) toothbrushes, toothpaste, shampoo and slippers.

    Many guests like the idea because they don't have to bring their own. But if you travel to Beijing, remember to bring these things of your own. That's because some hotels in Beijing have no longer provided guests with these disposables (一次性用品). Many disposable things are made of plastic. People throw them away after only using them once. It's a waste of natural resources (资源) and is very bad for the environment.

    In Beijing, people throw away about 19,000 tons of plastic bags and 1,320 tons of lunch bowls every year!

    Plastic can take 100 to 400 years to break down. So the less plastic we throw away, the better environment we will have.

    So, wherever you travel, bring your own things and use them again and again. Back at home and school, you can also do something to make our world a better place. Try to do these things in your daily life:

    Use cloth shopping bags, not plastic ones.

    After using a plastic bag, wash it out and let it dry. Then use it over and over again.

    Do not use paper cups.

    At your school canteen (餐厅), use your own bowls and chopsticks instead of disposable ones.

    There is little rain in deserts. Because deserts are so dry, they have no "quilt" to help stop the soil from going away. As a result, they may get very hot during the day with the sun shining, but don't hold the heat overnight. Many deserts can quickly get cold once the sun goes down. Some deserts can reach temperatures of over 100 degrees F during the day and then drop below freezing (32 degrees F ) during the night.

    The largest hot and dry desert in the world is the Sahara Desert in Northern Africa. The Sahara is a sandy desert with great sand hills. It covers over 3 million square miles of Africa. Other large deserts include the Arabian Desert in the middle East, the Gobi Desert in Northern China and Mongolia, and the Kalahari Desert in Africa.

    Animals that live in the desert are also used to needing little water. Many get all the water they need from the food they eat. Other animals keep water that they can use later. The camel stores up fat in its hump while other animals keep something they need in their tails.

    Only certain types of plants can live in the terrible environment of the desert. You won't see a lot of tall trees in the desert. Most plants have a way to keep water in their leaves, or trunks so they can live a long time without water.

    Now deserts cover around 20% of the world land, but they are growing. This is called desertification and is caused by different reasons including human activities. The Sahara Desert is growing larger and larger each year. What should we do with it?

    The first breath-taking pictures of the Earth taken from space showed it as a solid ball covered by brown land masses and blue-green oceans. We had never seen the Earth from that distance before. To us, it appeared as though the Earth had always looked that way and always would. Scientists now know, however, that the surface of the Earth is not as permanent (永久的) as we had thought.

    Scientists explain that the surface of our planet is always moving. Continents moves about the Earth like huge ships at sea. They float on pieces of the Earth's outer skin. New outer skin is created as melted rock pushed up from below the ocean floor. Old outer skin is destroyed as it rolls down into the hot area and melts again.

    Only since the 1960s have scientists really began to understand that the planet Earth is a great living machine. Some experts have said this new understanding is one of the most important revolutions in scientific thought. The revolution is based on the work of scientists who study the movement of the continents—a science called plate tectonics.

    The modern story of plate tectonics begins with the German scientist Alfred Wegener. Before World War One, Wegener argued that the continents had moved and were still moving. He said the idea first occurred to him when he observed that the coastlines of South America and Africa could fit together like two pieces of a puzzle. He proposed that the two continents might have been one and then split apart.

    Wegener was not the first person to wonder about the shape of the continents. About 500 years ago, explorers thought about it when they made the first maps of Americas. The explorers noted the east coast of North America and South America would fit almost exactly into the west coast of Europe and south Africa. What the explorers did not do, but Wegener did, was to investigate the idea that the continents move.