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    Astronauts (宇航员) face many problems when living in space stations. One of them is food. People on Earth put together all the meals first and then send these meals to space stations by space shuttle. Because the food has to last a long time (sometimes up to three months), people have to store a lot of it in cans. The space station does not have a fridge, but it has a cool room to keep fruit and vegetables fresh. Astronauts also eat many other foods such as dried meat that do not need special care.

    Without the help of gravity sitting down to eat can be difficult. Astronauts sometimes have to fix themselves to the wall while eating. They also have to be very careful so that food does not float away.

    We live in the world full of colours. Does a colour have weight? If you say “no”, you are wrong. If you don't believe, you may do an experiment.

    First, put two objects with the same weight into two boxes. Then cover the boxes. Third, wrap one box with a red piece of paper, the other woth a white piece of paper. Now hold the boxes with your hand one by one. It is certain that you think the red one is a little heavier.

    Why? A scientist found that different colours have different weight in a man's mind. So he did many tests and at last he found that every colour has its own weight in our mind and their order is the same. The heaviest colour is red, then blue, green, orange, yellow and white.

    The scientist told us that colours also have smell. Can you smell the colour? Of course not. Then why did the scientist say so? That is because every colour stands for a kind of light with a certain wavelength, and it reaches our brain through sense organs.

    According to this discovery, scientists say that people accept the colours they like, and refuse the colours they hate. So your body and mind will be healthy by using the colours you like. Or you'll be nervous or even get ill. For example, if you stay in a room with red windows, wallpapers and furniture for two hours, you'll feel you have been there for four hours. But if the room is blue, you'll feel you have been there for only an hour. Another example, if a person walks out of a red room and into a blue room, his temperature will fall. That means our body temperature will change with different colours.

    You probably know many of the things that you can do with the hundreds of different muscles in your body. But have you ever thought about how the muscles in an animal's body are different from yours? An animal's muscles are made to do the things that are most important for its life.

    Lions are hunters. They depend on their ability to catch other animals. Lions must be fast in order to catch their prey(猎物). The powerful muscles in their back legs allow them to run at speeds of more than 30 miles per hour. They can also jump a distance of more than 35 feet. The strong muscles in their front legs help them catch their prey.

    Snakes also use their muscles for hunting prey and for movement, but their muscles work in very different ways than lions' do. Because snakes do not have any legs, they use their muscles to push against the ground or other objects to move themselves forward. Their muscles also allow them to eat things that seem much too large. For example, a snake may eat an egg that is larger than the width of its body. How does this happen? The snake's strong neck muscles work together to push the egg down the mouth.

    The elephant's long nose has a lot of muscles. Scientists believe that the nose alone has more than 100,000 muscles! This is because the elephant uses its nose much in the same way that people use their hands and fingers. Even though the nose is large, it can perform surprisingly tasks. For example, an elephant can pick up a small leaf from the ground. The nose can also be a powerful tool. An elephant can use its nose to pick up a tree by its roots or even to lift a baby elephant.

    The great muscles of these animals seem pretty unbelievable. But the muscles in your body work exactly the way you need them to. After all, it might be fun to be able to jump a distance of 30 feet, but as a human being, there is just not much need for it.

    You may know about "junk food" like French fries. But do you know about "junk sleep"?

    Recently, a British survey found that electronic products（电子产品）in teenagers' bedrooms are affecting（影响）their sleep. The survey was done among 1,000 British kids from 12 to 16. It found that 30 percent of them got just 4 to 7 hours of sleep every day. But doctors say they need 8 to 9 hours.

    Almost a quarter of the kids said they fell asleep more than once a week while watching TV, listening to music or using other electronic products.

    "This is very worrying." said Dr. Chris Idzikowski, "We call it "junk sleep". It means you don't get enough sleep and the quality（质量）of the sleep is bad, too. If you don't get good rest, you won't perform well in school the next day."

    The survey found that 40 percent of the kids felt tired each day, with girls between 13 and 16 feeling the worst. Nearly all the teenagers have a phone, Mp5 or TV in their bedrooms. And many of them have all three.

    A fish that lives in America can live out of water for months at a time, similar to how animals got used to land millions of years ago, a new study shows.

    The Mangrove Rivulets, a kind of little fish, lives in small pools of water. When their living place dries up, they live on the land, said Scott Taylor, a researcher in Florida.

    The fish can grow as large as three inches. They group together and breathe air through their skin before they can find water again.

    The new scientific discovery came during a trip.

    "We were travelling for fun. And one day I kicked over a log (圆木) and the fish came out." Taylor told reporters by telephone. He said he would make his study on the fish known to the public in an American magazine early next year.

    In lab tests, Taylor said he found the fish can live up to 66 days out of water without eating.

    Some other fish can live out of water for a short period of time. The walking catfish found in Southeast Asia can stay on land for hours at a time, while lungfish(肺鱼) found in Australia, Africa and South America can live out of water, but only in a not active(活跃的) way. But no other known fish can be out of water as long as the Mangrove Rivulets and keep active, according to Patricia Wright, a biologist at a Canadian University.

    More studies of the fish may tell how animals changed over time.

    "These animals live in conditions similar to those millions of years ago, when animals began to move from water onto land." Wright said.