1.备份系统自带源
mv /etc/apt/sources.list /etc/apt/sources.list.bak
2.修改/etc/apt/sources.list文件，附带阿里中国镜像地址 阿里巴巴开源镜像
vim /etc/apt/sources.list
进入阿里巴巴开源镜像页面，找到ubuntu,点击后面的帮助，可以看到类似下面的介绍，加入就好。切记下面的第三步。
ubuntu 18.04(bionic) 配置如下 deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
3.更新生效
apt-get update