> For the complete documentation index, see [llms.txt](https://once-upon-a-phd.gitbook.io/once-upon-a-phd/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://once-upon-a-phd.gitbook.io/once-upon-a-phd/aurora/yi-qing-xia-de-qi-ji.md).

# 疫情下的契机