sudo vim /etc/apt/sourcellist
deb http://mirrors.163.com/ubuntu/ precise main universerestricted multiverse deb-src http://mirrors.163.com/ubuntu/ precise main universerestricted multiverse deb http://mirrors.163.com/ubuntu/ precise-security universemain multiverse restricted deb-src http://mirrors.163.com/ubuntu/ precise-securityuniverse main multiverse restricted deb http://mirrors.163.com/ubuntu/ precise-updates universemain multiverse restricted deb http://mirrors.163.com/ubuntu/ precise-proposed universemain multiverse restricted deb-src http://mirrors.163.com/ubuntu/ precise-proposeduniverse main multiverse restricted deb http://mirrors.163.com/ubuntu/ precise-backports universemain multiverse restricted deb-src http://mirrors.163.com/ubuntu/ precise-backportsuniverse main multiverse restricted deb-src http://mirrors.163.com/ubuntu/ precise-updatesuniverse main multiverse restricted