把其他的全部注释掉(#),用163的镜像,速度嗖嗖的。
deb
http://mirrors.163.com/debian/ stretch main non-free contrib
deb
http://mirrors.163.com/debian/ stretch-updates main non-free contrib
deb
http://mirrors.163.com/debian/ stretch-backports main non-free contrib
deb-src
http://mirrors.163.com/debian/ stretch main non-free contrib
deb-src
http://mirrors.163.com/debian/ stretch-updates main non-free contrib
deb-src
http://mirrors.163.com/debian/ stretch-backports main non-free contrib
deb
http://mirrors.163.com/debian-security/ stretch/updates main non-free contrib
deb-src
http://mirrors.163.com/debian-security/ stretch/updates main non-free contrib