Ubuntu下用多个Sources.list文件加速APT

$ cd /etc/apt/sources.list.d/
$ ls
00.list                 debian.ustc.edu.cn -> local
50.list                 debian.ustc.edu.cn_src -> mirrors.geekbone.org
$ ll *.list
lrwxrwxrwx 1 root root 5 2006-10-28 14:23 00.list -> local
lrwxrwxrwx 1 root root 18 2006-10-28 14:19 50.list -> debian.ustc.edu.cn
$ cat local
deb file:/home/user debs/
$ cat debian.ustc.edu.cn
deb http://debian.ustc.edu.cn/debian sid main contrib non-free
deb http://debian.ustc.edu.cn/debian-multimedia unstable main
deb http://debian.ustc.edu.cn/debian-uo sid marillat misc ustc
deb http://debian.ustc.edu.cn/debian-uo sid marillat misc ustc
deb http://debian.ustc.edu.cn/rarewares.org sid main
$ cat debian.ustc.edu.cn_src
deb-src http://debian.ustc.edu.cn/debian sid main contrib non-free
$ cat mirrors.geekbone.org
deb http://mirrors.geekbone.org/debian sid main contrib non-free