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I come from Holland (荷兰). In our country, there are plenty of windmills. There are more than 2,000 windmills in Holland. These windmills make electricity (电) for the country. It is a small country in Europe. About 20% of its land comes from the sea. The population of Holland is only 16,000,000. The weather is very nice, so the flowers can grow very well. Maybe you like roses, kapoks or lilies. However, the tulip is a symbol (标志) of the country. People celebrate Tulip Festival every year. There are a lot of cows in this country. You can enjoy good milk and cheese here. You can go everywhere by train, taxi, underground or ship. They are fast and convenient. People here also love to ride bikes. Riding a bike is free and relaxing. What do children do when they pass their exam? They often hang a schoolbag and a national flag at the gate! Come and have a good time in Holland!
Cu+Cu2+(未配平)。
气体产生；③溶液呈蓝色。