打开terminal，输入sudo gedit /etc/apt/sources.list，向该文件中添加源的地址即可，如，可添加如下地址
1 deb-src http://archive.ubuntu.com/ubuntu trusty main restricted #Added by software-properties 2 deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty restricted main universe multiverse #Added by software-properties 3 deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty-updates restricted main universe multiverse #Added by software-properties 4 deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse #Added by software-properties 5 deb-src http://security.ubuntu.com/ubuntu trusty-security restricted main universe multiverse #Added by software-properties 6 deb-src http://gb.archive.ubuntu.com/ubuntu/ trusty-proposed restricted main universe multiverse #Added by software-properties
之后执行sudo apt-get update，源地址便被更新了。