chapter 4 and 5 added.

1000-hours/sounds-of-american-english/5-sumup.md

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+# 5. 总结（Sum up）
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+其实，读音与拼写，就是学英语的 “最少必要知识” 了。所谓的 “最少必要知识”，指的是那些实际上很少很少，却可以做到 “只要掌握了之后就可以开始有资格有资本自顾自前行” 的知识。
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+Actually, pronunciation and spelling are the "minimum necessary knowledge" for learning English. "Minimum necessary knowledge" refers to the very basic yet crucial information that, once mastered, allows you to move forward independently.
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+练好了正确发音，掌握了基本的拼写，接下来就可以直接用英语了。尤其是在人工智能已经在语言学习方面超越了所有英语老师甚至英语词典和语法书的今天。有什么不懂的，有什么不会的，直接问人工智能就可以了。它的答案一定是最好的（尤其是在英语方面），剩下的，只有一件事，用。在用的过程中练，在练的过程中用。
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+If you get your pronunciation right and learn basic spelling, you can start *using* English *right away*. This is especially true today when artificial intelligence has surpassed all English teachers, dictionaries, and grammar books in language learning. Whenever there's something you don't understand, you can just ask AI. Its answers, particularly for English, will be the best. After that, there's only one thing left to do: *practice*. *Use* English in practice and *practice* while using it.
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+祝你好运！
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+Good luck!