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We've all heard of mermaids. They are the beautiful half-human, half-fish creatures(生物). They have the head and body of a human and the tail of a fish. We also know that mermaids only exist in fairy tales. But where did all the stories about these creatures come from? If you have ever seen a manatee, then you might have an idea.
Manatees, which are also called sea cows, are mammals(哺乳动物) that live in the sea. Since they are mammals, they have to swim up to the surface to breathe air. Many people believe that the story of the mermaid began with the ancient sailors who saw the manatees putting their heads out of the water to breathe. Because manatees are upright when they do this, it looks like they are standing. If a sailor saw a manatee doing this from far away across the sea, it is possible that the sailor would mistake the manatee for a creature that is half-human, half-fish.
Mermaids are described as having very long hair. This is probably because manatees like to swim up to the surface of the water in areas where there is sea grass. Manatees eat all kinds of plants in the sea, including sea grass. The sea grass around the manatee's head when they eat could create a picture of long hair.

Manatees also have powerful tails that are very similar to the fish-like tail of a mermaid. The sailors probably watched manatees come up for air and then swim back below the surface, using their paddle-shaped tails. This would explain why the sailors thought mermaids had fish-like tails.

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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.

    Zhalong is a nature reserve in Heilongjiang in northeast China．It is one of the world's most important wetlands．The area provides food and shelter for wildlife．It is an ideal home for different kinds of plants，fish and birds．

    Many birds live comfortably in Zhalong Nature Reserve all year round，while some only stay for a short time．There are many fish in the wetlands，and the birds can easily catch them for food．Zhalong Nature Reserve is an important living area for the rare red-crowned cranes．There are not manyred-crowned cranes in the world．Some of them live in Zhalong．

    Some people want to change the wetlands to make more space for farms and buildings．This means that there will be less and less space for wildlife．

    More and more birds are in danger because they do not have enough living space．Many of them died．The Chinese government wants to protect these endangered birds，and they can be safe in Zhalong．

    Every year a lot of tourists go to Zhalong to watch birds．This year members of ourBird watching Club are going to study the different kinds of birds in Zhalongand the changes in their numbers．The study begins next month．

    We do a bird count once a year．We are now inviting secondary school students to help．We need more people to help us count and do something to help the birds．Many people do not understand the importance of the wetlands．We hope this information will help them understand and make them actively take action to protect wildlife．

    Birdwatching is a fun hobby. Many people enjoy it every day. You can also enjoy it. Birdwatching does not have to take a lot of time or money. With materials(材料) around your house, you can build a good birdhouse. You can start birdwatching in 30 minutes in your very own yard. It's very easy!

    Materials you will need:

    Milk box        ●Glue        ●Scissors      ●Brown paint        ●Tools for painting

    To build a better birdhouse

    ⒈Clean and dry the milk box.

    ⒉Glue the top of the milk box shut.

    ⒊Cut holes into the milk box for the birds to get into the birdhouse. The size you use will determine which birds use the house. You can cut one hole per side, or two. A good place to cut is about four inches(英寸) from the bottom(底部).

    ⒋Paint your milk box brown. The color helps the birdhouse mix with the tree.

    ⒌Cut holes into the milk box in the bottom of the box to let out any dirty things. Add at least two small holes on the top of the box. The top holes are to let in clean air. Do this after painting, or the paint could fill in your holes!

    ⒍Put the box in a tree. You can see the birdhouse from a window of your house. Now you can watch your birds in any weather!

Here are four clothing stores.

Notes: £ means the cheapest; £ £ £ £ means the most expensive;

★ means friendly; ★★★★ means the friendliest

    When the weather is hot, you go to a lake or an ocean. When you are near a lake or an Ocean, you feel cool. Why? The sun makes the earth hot, but it cannot make the water very hot. Although the air over the earth becomes hot, the air over the water is still cool. The hot air over the earth goes up. Then the cool air over the water moves in and takes the place of the hot air.

    Then you may ask, "Why is the ocean full of salt?" Scientists will say that the salt comes from the rocks. When the rocks get very hot or very cold, they crack (爆裂). Rain falls into the cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. And then you may doubt, "But the ocean does not get more salty every year. Scientists are not sure about the answer to this question.

    We know a lot about our world. But there are still many answers that we do not have, and we are curious about them.