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Giúp mk với mk cảm mơn ạ Câu 5: Một người dùng mặt phẳng nghiêng kéo một vật có khối lượng 100 kg lên cao 5m a/ Nếu không có ma sát thì lực kéo 500N.Tính chiều dài mặt phẳng nghiêng b/ Thực tế có ma sát và lực kéo vật 550N .Tính hiệu suất mặt phẳng nghiêng
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IX. Read the text carefully, then answer the questions. Modern graffiti began in big cities in the United States in the 1970s. One of the first ‘taggers’ was a teenager called Demetrius. He wrote his tag TAKI 183 on walls and in subway stations in New York. Other teenagers saw Demetrius’s tag and started writing their own tags on walls, buses and subway trains all over New York. Then, some teenagers started writing their tags with aerosol paint. Their tags were bigger and more colourful. Aerosol paint graffiti became very popular in the 1970s and 1980s and appearedon trains, buses and walls around the world. In the 1990s and 2000s, a lot of graffiti artists started painting pictures. In some countries, writing or painting on walls is a crime and street artists can have problems with the police. In other countries, artists can draw and paint in certain places. For example, in Taiwan, there are ‘graffiti zones’ where artists can paint on walls. In São Paulo in Brazil, street artists can paint pictures on walls and houses. Their pictures are colourful and beautiful. Some tourists visit São Paulo just to see the street art! 1. Where did modern graffiti begin? 2. What was Demetrius’s tag? 3. What did young people write on New York walls? 4. When did aerosol paint graffiti become popular? 5. Is graffiti legal in every country in the world? 6. Where can artists paint in graffiti zones?

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