Why do plants grow in some places and not in others? Why does some land have so many plants growing on it, while other land has almost no plants growing on at all?

    To grow, plants need some things. One is warmth. In very cold places, almost nothing grows, Plants also need water. In very dry parts of the Earth, only a few unusual plants can grow. That's why dry deserts(沙漠）almost don't have trees or grass.

    Plants must also have a place in which to put down their roots（根）and grow. They find it difficult to grow on hard land. The town is on hard land. The plants here can only grow in the soil（土壤）between the cracks of the stones.

    Another thing plants must have before they can grow is food.

    What will happen if we try to make things grow on the sandy（有沙的）beach? A few plants, such as beach grass, will grow in sand, but most plants won't. Even if（即使）the weather is warm enough and we water the plants each day, many of them will die because the sand on this beach has almost no food for plants.

Are You Right Handed or Left Handed?

    Which hand do you use when write? About 8 to 15 percent of people are left handed. They often have to use tools that are designed for right-handed people. So it is difficult for left-handers to use most tools. If you are right handed, try this experiment: Take a knife with your left hand and try cutting a potato into pieces. Don't be surprised if you feel awkward（别扭的）.

    In the past, people thought it was strange to use the left hand. Young students looked down upon their left-handed classmates. Some children were even punished for using their left hand to write. But these days parents and teachers have accepted that. In almost every school in the world, left-handed students can use their left hand to write.

    What causes people to be left handed or right handed? Experts have searched long and hard on this. They conclude（得出结论） that left-handed people are left handed for the same reason that right-handed people are right handed. One out of every ten people just is a left-handed people are right handed. One out of every ten people just is a left-hander. It's simply like the color of our eyes – some people have brown eyes, while some others have black eyes.

    However, may researchers think that left-handers and right-handers are different in some aspects. Right-handers are more talkative and outgoing than left-handers. Many right-handed people understand spoken words better. For example, after they listen to directions to a supermarket, they can find it easily. Right-handers are good at organizing people, too. They are also better basketball guards. Just ask Yao Ming.

    Research shows that left-handers are creative and artistic. Many famous performers, like Jim Carrey and Paul McCartney, are left handed. Many left-handers learn better visually（在视觉方面）. In art, both Leonardo da Vinci and Michelangelo were left handed. In music, Ludwig van Beethoven was left handed. In science, you find Newton and Einstein. The left-handed people are also really good at tennis and other single sports.

    If you prefer one hand, but you are still good at writing with the other, you are mixed. Research shows mixed-handers can remember everyday things better than other people. What did you eat for lunch two weeks ago? If you're mixed handed, you can probably remember.

    People already know a lot about animals. However, there are still some things about animals that may surprise you. Here are some facts about animals you probably didn't know.

    Cows do have best friends and feel stressed when they are separated. Scientists have found that cows are very social animals and a cow always makes friends with other cows. When a cow is with its friends, it feels relaxed, compared with when it is alone.

    During breeding season, a male penguin(企鹅) will offer a small stone to a female penguin as a gift. If she takes it, they will become partners. When the female penguin lays an egg, she and her partner may carry it on their feet, because some penguins don't build nests(鸟巢).

    Crocodiles(鳄鱼) swallow(吞) stones. Crocodiles always swallow their food instead of eating it like other animals. They swallow stones which break the food into very small pieces in their stomachs. These stones may stay in their stomachs all their lives.

    Elephants use plants to treat pain or other illness. Scientists once found a pregnant (怀孕) elephant in Africa who ate a kind of plant which was not part of her normal food. Four days later, she gave birth to a baby elephant. The same plant was used by the local pregnant women.

    What can 3-D printers*make? They can make lots of things, such as toys and car parts. But what about a house? In the Netherland 3-D printed houses will soon come into life, according to The Guardian

The Netherlands is the first country to have this technology*.

    Scientists plan to build five houses with 3-D printers. The first house will be finished by the end of 2019. It will be a house with three bedrooms. For the first house, only the walls will be 3-D printed. A 3-D printer will print it with a special cement. The printer will print it layer upon layer to build the walls. After that, workers will make the wall stronger.

    By the time they start working on the fifth house, the scientists hope that most parts of the house will be made with 3-D printing. Even the windows can be made with a 3-D printer.

    The 3-D printed houses have many advantages. For example, they use less cement than traditional houses. It can help save a lot of money. Also, 3-D printing can make buildings in almost any shape*. Traditionally-built homes usually come in just a few shapes

    The American Computer &. Robotics Museum was open to visitors in 1990 in Bozeman, Montana. At first it was planned to build in Princeton, New Jersey. The founders moved to Bozeman in 1988 and after looking at the area they decided to build the museum there. With Yellowstone National Park to the south and Glacier National Park to the northwest, the museum attracts thousands of visitors from all 50 states and over 50 countries. The American Computer &. Robotics Museum has been written about in many publications such as The New York Times, The New Yorker, Los Angeles Times, QST and USA Today.

    When visitors first enter the museum, they are shown a video introducing the museum and its collections. All visitors are given the chance to join in tours led by friendly tour guides. We have had visitors aged from3 to 93- it is a big family. Over 1,000 exhibitions are shown in the 6, 000-squaremetre museum. Travelling through our museum, you will see the exciting 20,000 years of history of the information age. Technology becomes easier to accept when one learns about its origins(起源) in the natural process(进程) of human development.