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

    To grow,  plants need several 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) everywhere are almost not covered by trees or grass.

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

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

    What will happen if we try to make things grow on the sandy beach? A few plants, such as beach grass, will grow in sand, but most plants won't. Even if 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 plant food.

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    If you go into the forest with your friends, stay with them. If you don't, you may get lost. If you get lost, this is what you should do. Sit down and stay where you are. Don't try to find your friends—let them find you. You can help them find you by staying in one place. There is another way to help your friends or other people to find you. You can shout or whistle (吹口哨) three times. Stop. Then shout or whistle three times again. Any signal (信号) given three times is a call for help.

    Keep up shouting or whistling. Always three times together. When people hear you, they will know that you are not just making a noise for fun. They will let you know that they have heard your signal. They will give you two shouts or two whistles. When a signal is given twice. it is an answer to a call for help.

    If you don't think that you will get help before night comes, try to make a little house with branches (树枝). Make yourself a bed with leaves and grass.

    When you need some water, you have to leave your little house to look for it. Don't just   walk away. Pick off small branches and drop (扔下) them when you walk to go back again easily. When you are lost, the most important thing to do is to stay in one place.

    Owls live in almost every country in the world. Most owls don't sleep at night. When they fly, you can't hear them. They are very quiet. Owls are good at hunting（捕猎）. They eat a lot of things such as mice, snakes, small birds and even fish. Owls have very good hearing. That helps them to hunt well in dark places. Their eyes are special. Both of their eyes face front. They can see very far away. There are facial disks(面盘) around their eyes. These facial disks can help with their hearing. Owls can turn their heads 270°. That helps them see what's going on all around them.

    Maybe because owls look a little different and have special life habits. There are a lot of stories about them. Some cultures believe that owls are very clever and some cultures think owls may bring bad luck to people. In fact, owls are really good friends of people. They eat lots of mice every year. That helps save a lot of food for people. But the number of owls in the world is becoming smaller and smaller because of people's activities. Now owls are protected by law(法律) in many places of the world. For example, in some places, people can't keep an owl as a pet at home.

Billy Ray Harris was homeless. He spent each day on the streets of Kansas City, begging for money or food. Every day, as he sat thinking about his life, he occasionally heard the sound of a coin or two coming into his cup. One day, the noise was louder than usual. If Billy had looked up, he'd have seen a young lady on her way to work. But he didn't. Later when he looked into the cup, he could hardly believe what he saw. At the bottom was a shining diamond ring.

Billy's first thought was to go straight to a jeweller's(珠宝店) and that's exactly what he did. To his amazement, he was offered $4,000. Billy thought long and hard. Was this a mistake? It was more money than he'd seen in a long time. But then he thought about his grandfather, who had brought him up always to do the right thing, and knew he had to reconsider. His mind was made up. He'd keep the ring and maybe one day its owner would return.

Two days later, a young woman came while he was begging. She introduced herself as Sarah Darling and asked if he'd found anything unusual in his cup. Billy reached into his pocket and pulled out the ring. When he saw the smile on her face, he knew he'd made the right decision. She explained when putting the coins into his cup, she'd forgotten putting her ring in her purse.

But the story doesn't end there. Sarah told her husband the story and wanted to post it on the Internet. He thought it was a good idea. They also called on raising money for Billy. They had more than $185,000. Billy Ray Harris no longer spends his days begging. He has a home and a job. The story also made the local news and he was reunited with his two sisters, who he hadn't seen for 16 years. If he hadn't done the right thing, he wouldn't have seen his sisters again.