1.打开网页https://mirrors.ustc.edu.cn/repogen/
2.复制Ubuntu下面所有内容
deb https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-backports main restricted universe multiverse
## Not recommended
# deb https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-proposed main restricted universe multiverse
# deb-src https://mirrors.ustc.edu.cn/ubuntu-old-releases/ubuntu/ hirsute-proposed main restricted universe multiverse
3.在终端进入cd /etc/apt,ll查看sources.list
4.输入命令：sudo vi sources.list,使用d删除里面所有内容
5.粘贴刚刚复制的内容，wq保存退出
6.在终端输入:sudo apt install update即可
