> For the complete documentation index, see [llms.txt](https://www.oulan.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.oulan.com/2017/04/20.md).

# 20

拿来容易长大难。用心呵护，你的未来。早安，有雾，负离子保护。

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