When US student Olivia Priedeman, 17, woke up one morning, she thought she had had a dream about making plans with a friend.

    But it wasn't a dream. Her phone showed that during the night, Priedeman had read a text message from her friend. She did it while she was fast asleep.

    Reading and sending text messages while asleep called─ "sleep texting"─ is an unusual sleep behaviour, similar to sleep walking. It's also a growing problem among doctors: young people can't live without their cell phones.

    One in three teenagers sends more than 100 text messages a day, according to the Pew Internet & American Life Project. And at least four out of five teenagers said they sleep with their phone on or near their bed.

    Elizabeth Dowdell, a professor at Villanova University in Pennsylvania, has studied sleep texting. She said that having a phone nearby all night is a big part of the problem.

    Andrew Stiehm, a sleep medicine researcher with Allina Health in Minnesota, agrees. It's possible for the part of the brain that controls skills to wake up, while the part of the brain that controls memory and judgment(判断) may be still asleep. That's why some people can perform basic movements-such as walking, talking, texting or even driving while they're sleeping. Some of Dowdell's students said that they're disturbed by their nighttime texting behaviour. But because sleep texting is unconscious, it's a difficult habit to break. Dowdell said she knows of some students who wear socks on their hands to keep themselves from texting.

    Marjorie Hogan, a doctor at Hennepin County Medical Centre in Minneapolis, Minnesota, suggests keeping all electronic products outside the bedroom.

    Animals are our friends. We can find1different kinds of animals. Some animals are living 2 big woods(森林). And some animals are living with 3. Animals are very4 to people. People can teach the elephant to do some heavy 5. And they can also teach the dog to 6the house. A watch dog is very 7 It can help people in danger(危险). So people 8dogs very much. Most of9like to go to the zoo.10there are many animals in zoos. Zoo is a good place for children to get to know animals.

    When you hear the word "scientist", what do you think of it? Many people think scientists are people in clean white coats, working in labs( 实验室). Some scientists do work in labs. But there are 1 scientists working in woods and jungles(丛林).  These scientists are called " animal behaviour (行为) scientists", and they study animals as they live in nature. Why don't these scientists catch animals and study them in zoos? The 2 is in the word "behaviour". Animal behaviour scientists want to learn 3 animals behave in their wild homes. When animals live in cages or in zoos, they do not act 4 as they do in the wild. They may fight (打架) 5each other, or they may not eat, or they may not raise (抚养) their babies as they usually do. To see real animal behaviour, scientists must go to the places 6the animals live. So animal behavior scientists go into the jungles, the woods or the deserts. There, 7most important tools are their eyes and ears. They watch and listen to the animals very 8. They write down everything that happened in notebooks. Though they live near the animals, the scientists are careful not to frighten them. If the scientists are 9, the animals will pay no attention to them. Then the scientists can see how the animals really live.

    The animal behaviour scientists hope what they've learned about animal behaviour can provide clues(提供线索) 10people learn to live with animals together more happily.

    Everyone knows water is important to all living things. But do you know these interesting 1about water?

    Without water, the Earth would look 2the Moon. People can live for a long time without food, but only 3 days without water. Scientists say about 70% of the human body is made up of water. Water4 up about 83% of our blood, 75% of our brain, and 80% of our lungs(肺）. About 95% of a tomato is water, and about 80% of an apple is water. So 5can we do to help with water problems?

    Keep a shower to 10 minutes or6 time. It helps save much water. Use a broom to sweep the floor, the stair, the garage(车库），or the sidewalk instead of water.

    7throw your used water away. Instead, you can use some to water plants or run the toilets. Use a bucket(桶）of water to 8 your bike or the family car instead of water pipes.

    Use water only9you need it. Don't leave water running. Be sure to turn the tap 10when you are not using it.

    There was a small village near the mountain. There were a lot of trees in the mountain. People in the 1 always got something from it, such as animals and trees.  When they wanted to 2 a house, they cut down the trees. And they also killed the animals for 3 . Trees were very 4 in their daily life. They made tables, chairs 5   beds by cutting down the trees. In addition, when they 6 meals, they still used some trees for wood. However, they only cut down trees but 7planted new trees. So the trees were fewer and fewer; the animals were becoming 8 as well.

    One summer, it rained 9in the village. The rain lasted for about a week. The soil(土壤)and the stones on the mountain fell down and soon 10  the whole village. They finally knew they should not only cut down trees but also needed to protect them.

    What is the most important invention of all time? Is it the written word that helps us to record information? Is it the telephone that lets us talk to people 1 all over the world? Is it the car that lets us travel at great speeds to meet 2? Umberto Eco, an Italian writer, thinks it is something quite different. He says the most important invention might be right in front of your 3. He is talking about a simple pair of glasses.

    Modern eye glasses were 4 about 1,000 years ago. They were more than just a convenient way 5. Before glasses, writers, scientists or teachers 6 could not see properly had to memorize everything. After about ten years of poor eyesight, they could not remember well enough 7 could not work. Glasses meant that people could work into their old 8. People who wanted to remember some information could 9 and read it. Eye glasses are one of the world's greatest inventions and were probably 10 by the people who designed the first telephones and cars.