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    There is a lake near a forest in Sweden. The water in the lake is very clear and everything is quiet and still. On the far side of the water is some farmland and further away, across the field, is an old church built on a hill. It has just stopped raining. The brook(小溪) flowing into the lake is full and there is still some half-melted(半融化的) snow from last winter on the ground.

    The reason the water is so clear, and everything is so quiet and still, is that most of the plant and animal life in and around the lake is dead. There are no birds because all the fish and insects, which the birds need for food, have disappeared. Many trees in the forest are losing their leaves and bark (树皮), and are sick and dying. Others were blown down by the high winds of last winter. A farmer is working in a field planting something, but unless he plants a stronger kind of seed this year, the crop will be between 25 to 40 percent lower than a few years ago. The stones of the old church tower are turning to powder and unless the tower is repaired soon, it will fall down.

    All the death and destruction(破坏) in this place is caused by the smoke coming out of factories and poisonous gases from cars and trucks. And yet this silent lake is hundreds of meters aways from the nearest factory and highway.

    Traveling（旅行) is one of the most important activities and people were interested in it many years ago. Modern traffic develops(发展) fast, so traveling to different places has become much faster than before.Staying healthy while traveling can make your trip happier. But do you know how to keep healthyduring a trip? The following advice may be useful to you.

    Before leaving

①Wear comfortable shoes, a hat and sunglasses.

②Take some medicine that you need with you. They can be used when you get ill or have other problems.

③Do some exercise for weeks or months before you leave if you plan to do lots of walking or climbing during your trip.

④Prepare（准备） proper (适当的)food. Take bread, biscuits and some fruit for a long time. They don't go bad quickly. Bring meat, fish, eggs, milk and even salads and vegetables for a nearer one.

While traveling

①Be sure not to eat dirty food or bad fruit.

②Have enough time to take a rest during your trip.Itcan help you become more relaxed.

③Tap（水龙头）water is not safe, so drink bottled water and always clean the cover of the bottle.

④Keep food in good condition（状态）. Remember: If you travel with food, keep hot food hot and cold food cold.

    3D printing is becoming more and more popular. We are now able to print things such as clothing, prosthetic limbs (假肢), musical instruments(乐器) and so on. People and businesses are able to create the things they need very quickly and easily using 3D printers.

    But can you imagine printing food? Some scientists are trying to revolutionize our eating experience by doing this. They hope that having a 3D printer in the kitchen will become as usual as the microwave or blender. Scientists say that they are easy to use: you simply have to choose a recipe and put the food "inks" into the printer. You can also change the instructions to make the food exactly how you want it. This means that it would be very quick and easy to create delicious meals.

    Using 3D printers to create your meals would also be saving the environment. There would be less need for traditional growing, transporting(运输) and packaging as food production would be quicker and easier.

    Printing food could also help people who suffer from dysphasia (吞咽障碍症). They could program (为…编程) the printer to print softer versions of their favorite foods so that they would not have trouble eating them.

    However, some people think that the future of 3D-printed food would be a disaster. It could take away many jobs, including those for growing, transporting and packaging food. Imagine a world where there was no need for farming or growing crops and the same tastes could be printed from a raw "food ink". Similarly, traditional cafes and restaurants might lose business. Also, there are worries about the printed food: is it really possible to get the nutrients (营养物) we need from food-based inks and gels?

    What's more, cooking and eating together with family and friends has long been a traditional and enjoyable activity. It is hard to imagine a world where the fun of cooking is dead and meals can be done at the touch of a button.                                                        

What do you do when you feel unhappy? Do you listen to music? Do you talk to a friend? Maybe next time you feel sad, you should try going outside if it is sunny. Doctors know that how much sunlight we get can change (改变)how we feel. Scientists learn this by asking people who live in different parts of the world. In the far north, in Alaska or Finland, for example, the days are very short in winter. People living in these places say that they often feel unhappy in winter. In the south, where there are more daylight hours, fewer people say they are unhappy in winter. The reason is how much sunlight these people get each day. Sunlight changes the things inside our bodies, and they can change the way we feel. A couple of hours of strong sunlight or light from special lights can help our body make us feel happy. Another way to feel happier is to get some exercise. Just like sunlight, exercise helps our bodies make certain chemicals(化学物质), which make us feel happier. In addition, exercise helps people sleep better. Exercise also helps you get away from stress (压力). When you are angry or upset about something, exercise is a good way to get those bad feelings out of you.

As we know, there are many kinds of clubs in the American middle schools, such as the music club, the sports club, the chess club, the swimming club. But do you know the homework club?

The homework club is a popular(流行的)club in many American middle schools. More and more students spend their afternoons in the homework clubs. The American middle school students need a quiet place to study. But games, computers and TVs are all around kids at home. So the homework club is just for them to do their homework. The club is very quiet and it's good for students to study. Some teachers are there, too. They can answer students' questions and help with their homework. If students finish their homework on time, they will get a snack(零食). It's always children's favourite food. Then they can go home and play games or watch TV happily.

①Winter can be a hard time for animals. The weather may be very cold. Food can be hard to find under the snow. How do animals live in this season? Let's have a look. 

②In autumn, when the weather gets cool, some animals go away from cold places. Some birds fly south together. They move south because the weather there is warm and food there is easy to find. When spring comes, they will return. 

③Many animals store(储存) food before the cold days. That is what a pika(鼠兔) does. A pika looks a little like a rabbit, but with short ears. Pikas live in high mountains where winters are long and cold. In summer, they prepare lots of grass to eat in winter. By the end of summer, a pika may store about 22 kilos of grass. 

④Some animals change themselves to live in winter, like snowshoe rabbits in America. In summer, the rabbits' fur is brown. But they grow new, white fur in winter. The new fur keeps them safe in the snow. In autumn, they eat to get fat(脂肪), because the fat can also help them keep warm in winter. 

⑤Other animals sleep all winter long and don't eat at all. Before winter, these animals eat a lot to grow fat. When winter comes, they go to sleep. Black bears in cold areas make warm beds to sleep in. Some of them can sleep for seven months. By the time spring comes, they have lost most of their fat.