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    In today's world, sleep experts say that for a better night's rest, Americans should turn off their smartphones or iPad before sleeping. Such electronic products make the brain more active, and then influence their sleep. But according to a latest survey, more than 90% of Americans regularly use a computer or some other kinds of electronic products in the hour before bed.

    Researchers are finding that man-made light from some electronic products at night may reduce the brain chemicals(化学物质) that help sleep. The researchers showed that sitting in the light from computer tablets clearly lowered levels of the chemical which manages our body clocks and plays a role in the sleep cycle.

    In the study, the researchers let volunteers read, play games and watch movies on a tablet for different time while measuring(测量) how much light their eyes received. They found that two hours of sitting before a bright tablet screen at night reduced the sleep chemical levels by about 22%.

    Studies of students using computers at night have got the similar results. And researchers say that may not only cause sleeplessness, but also raise the risk of obesity(肥胖症), diabetes(糖尿病) and other diseases.

    To be on the safe side, the researchers advise us to use computers less before bed, or at the very least turning down your screen as much as possible.

    How much do you know about the universe? In the huge universe, there is the Galaxy and many other galaxies. In the Galaxy, there is the Solar System and lots of other stars. In the Solar System, there is the sun, the earth and seven other planets. As we know, the eight planets go around their star —the sun. In our Earth—moon System, the moon goes around the earth. And because our earth keeps turning around the sun all the time, we have day and night. When our part of the earth turns to the sun, it is day. When our part of the earth turns away from the sun, it is night.

    Just because the moon is closer to the earth than the sun, it looks much bigger than the sun. The sun is big enough to give out very strong light. The moon itself can't give any light at all, but it looks quite bright, too. In fact, the light from the moon comes from the sun. Although, the moon looks much bigger and brighter than the sun and other stars, in fact, all the stars are much bigger and brighter than the moon. They look smaller than the moon also because they are farther away from us. It's clear that big things will look smaller when they are farther, and small things look bigger when they are nearer.

So far, we have traveled to many other planets in the universe. But scientists haven't discovered any living things on any other planets. Scientists haven't discovered any other planets with a good environment. They aren't sure if there is any water and air for living things to live on other planets. People always ask the question: Is there anyone out space? Our scientists haven't got a clear answer either. Some people think it will be a secret for a long time. But we believe we can solve the problem some day.

Exploring our Solar System and the universe is a great national project to some countries. Our Chinese scientists are also trying to send spaceships with astronauts to those planets and even the universe. At 9:00 a.m. on October 15th, 2003, a Chinese astronaut called Yang Liwei was sent up to space. He stayed there for hours and got back to the earth at 6:00 a.m. the next day. It was the first time for Chinese to have a space travel.

    Christmas is coming.1 you are thinking what gifts you need to buy, the Alice Ferguson Foundation is busy 2 the environment by building relationships between people and nature.

    At the 3 of the year, it designs events to help children celebrate Christmas without increasing the amount of 4 they create.

    Hanna Seligmann who works for the foundation, said they 5 that from Thanksgiving Day to New Year's day, the household trash increases by 25 percent. Many young people do not know the6 they throw away do not decompose (分解), or break down, at the same rate. For example, paper dissolves（溶解） in about four weeks. A metal can take up to 100 years. A plastic bag will not decompose for 450 years. Glass takes 1,000 years.

    Hanna Seligmann shows adults and children 7to reduce waste during the holiday gift-giving season.

    She encourages using things that are 8 in our houses like newspaper or old magazines. With imagination，children can wrap gifts in a 9 napkin or even a beautiful scarf. In fact，there's no better way to celebrate the holiday by giving10to the planet.

    Nowadays, WeChat is becoming more and more popular in China. No matter where we are, we can sign up and send text or voice messages to our friends. We can also find a stranger to talk to by shaking the 1^. Another funny function is that WeChat can help to search for people  2 live nearby with the programme on. Many people like this function, 3 it can help them to find more people who they may know.

    In my opinion, WeChat is really4 useful chatting tool. It can help people 5 with their friends more easily.6 , it is also bad for people, especially for students .As you see, some people use WeChat 7 too long. It is not healthy to them .So I have some 8 on how to use it in a correct way. First, we should not use it when we are studying. We can't focus on our study if we use it. Second, we must be careful. We should neither show too much personal information9 trust strangers so much.

    We should learn how to use it properly. Remember, WeChat is not everything in your life.10depend too much on it.