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       Do you think stones (石头) can move by themselves? There are some famous moving stones in Death Valley, the US. Many of the stones are small but a few of them are very big. Some of the big stones are as big as a man. The biggest stone weighs about 350 kg. The stones only move at night. Nobody has ever seen them moving, but now scientists (科学家) know the answer to the question. The answer is the wind. When the wind comes from the west, the stones move to the east. When the wind is from the south, they always move to the north. But how can the wind move a very heavy stone?

        Death Valley is one of the hottest place in the world, but it can be very cold at night. Sometimes, there are even bad storms (暴风雨) at night. Rain falls, and the wind is strong and cold. The water on the ground turns into ice easily. Then the strong wind can move the stones along the ground. In the morning, the sun comes up and dries (使……变干) the ground. So people can find them move from one place to another in the daytime.