系统版本 Ubuntu 18.04.6 LTS 64位
1 被封原有源
sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak 备份原来的sorce文件
2修改sources.list文件
sudo gedit /etc/apt/sources.list
3 删除原有信息，换成如下库
# 中科大镜像源deb https://mirrors./ubuntu/ bionic main restricted universe multiversedeb-src https://mirrors./ubuntu/ bionic main restricted universe multiversedeb https://mirrors./ubuntu/ bionic-updates main restricted universe multiversedeb-src https://mirrors./ubuntu/ bionic-updates main restricted universe multiversedeb https://mirrors./ubuntu/ bionic-backports main restricted universe multiversedeb-src https://mirrors./ubuntu/ bionic-backports main restricted universe multiversedeb https://mirrors./ubuntu/ bionic-security main restricted universe multiversedeb-src https://mirrors./ubuntu/ bionic-security main restricted universe multiversedeb https://mirrors./ubuntu/ bionic-proposed main restricted universe multiversedeb-src https://mirrors./ubuntu/ bionic-proposed main restricted universe multiverse# 阿里镜像源deb /ubuntu/ bionic main restricted universe multiversedeb /ubuntu/ bionic-security main restricted universe multiversedeb /ubuntu/ bionic-updates main restricted universe multiversedeb /ubuntu/ bionic-proposed main restricted universe multiversedeb /ubuntu/ bionic-backports main restricted universe multiversedeb-src /ubuntu/ bionic main restricted universe multiversedeb-src /ubuntu/ bionic-security main restricted universe multiversedeb-src /ubuntu/ bionic-updates main restricted universe multiversedeb-src /ubuntu/ bionic-proposed main restricted universe multiversedeb-src /ubuntu/ bionic-backports main restricted universe multiverse
将上面的镜像源覆盖到sources.list里，保存。
4更新源
sudo apt-get update 更新源
