Ubuntu 20.04 18.04 软件源Ubuntu 20.04 18.04 软件源参考
# 默认注释了源码仓库，如有需要可自行取消注释deb https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiverse# deb-src https://mirrors.ustc.edu.cn/ubuntu/ focal main restricted universe multiversedeb https://mirrors.ustc.edu.cn/ubuntu/ focal-security main
