> 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/2020/03/30.md).

# 30

譬如有两个水管。一根儿水流稳定，粗细不变。另一根，水流一会儿大一会儿小，管子有的地方一会粗一会细。哪一根更容易出现问题？

![](/files/IDNM1kIkVISoz3sNxORp)