2017年5月14日“一带一路”国际合作高峰论坛在北京举行，“合作、共赢”成为世界人民的共同追求。历史上就有一些史实证明了这一观点。识读如图三幅图，探究相关问题。

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     Do you live in a city? Do you know how cities began? Long long ago, the world had only a few thousand people. These people moved from one place to another. They moved over the land, hunting animals for food. No one knows how or when these people learned about growing food. But when they did, their lives changed. They did not have to move houses any more. They could stay in one place and grow it. People began to live near each other, so the first village grew. Many people came to work in the villages, and these villages became larger and larger. Then people had machines, life in the villages changed again. People built factories. More and more people lived near the factories. So the villages grew into cities. Some of them grew very big. Today, it’s strange that some people are moving back to small villages. Can you tell me why ?