1.复制源文件备份，以防万一

sudo cp /etc/apt/sources.list /etc/apt/sources.list.back1

2.编辑源列表文件

sudo vim /etc/apt/sources.list

#将原有的内容注释掉，添加以下内容
deb https://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse

deb-src https://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse

deb https://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse

deb-src https://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse

deb https://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse

deb-src https://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse

deb https://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

deb-src https://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

deb https://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse

deb-src https://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse12345678910111213141516171819202122

3.更新软件源

sudo apt update

sudo apt upgrade