Ubuntu全版本通用换源教程：

打开终端：按下 Ctrl + Alt + T组合键，打开终端。

备份源列表文件：在终端中执行以下命令备份原有的源列表文件：

sudo cp /etc/apt/sources.list /etc/apt/sources.list.backup

修改源列表文件：使用文本编辑器（例如nano或gedit）打开源列表文件：

sudo nano /etc/apt/sources.list

替换默认源：用下面提供的新源地址替换文件中的内容（根据你所在的地理位置选择一个可用的镜像源）：

# 默认官方源

deb http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse

deb-src http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse

deb-src http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse

deb-src http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse

deb-src http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse

# 阿里云源

deb http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted universe multiverse

deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse

将 focal替换为你使用的Ubuntu版本代号，例如 bionic、xenial等。

保存并关闭文件：按下 Ctrl + X，然后按 Y确认保存，最后按 Enter键退出编辑器。

更新软件源：执行以下命令更新软件源列表：

sudo apt-get update

现在，你已经成功地更换了Ubuntu系统的软件源。新的源地址将提供更快的下载速度和更稳定的软件包更新。