为什么要更新源呢？
源是linux中用apt-get命令安装软件时，搜索的网址。因为系统里默认的源下载速度可能不够快，而更新一下，配置一些快一点的源，可以使速度提高。
首先，用sudo cp /etc/apt/sources.list /etc/apt/sources.list.bak备份一下，
然后再来编辑：gedit /etc/apt/sources.list
最后再更新一下就行了：apt-get update
把里面的内容都删除了，改成下面的源，当然你还可以在网上查找一些更快的源换上去。
#网易 deb http://mirrors.163.com/ubuntu/ lucid main universe restricted multiverse deb-src http://mirrors.163.com/ubuntu/ lucid main universe restricted multiverse deb http://mirrors.163.com/ubuntu/ lucid-security universe main multiverse restricted deb-src http://mirrors.163.com/ubuntu/ lucid-security universe main multiverse restricted deb http://mirrors.163.com/ubuntu/ lucid-updates universe main multiverse restricted deb http://mirrors.163.com/ubuntu/ lucid-proposed universe main multiverse restricted deb-src http://mirrors.163.com/ubuntu/ lucid-proposed universe main multiverse restricted deb http://mirrors.163.com/ubuntu/ lucid-backports universe main multiverse restricted deb-src http://mirrors.163.com/ubuntu/ lucid-backports universe main multiverse restricted deb-src http://mirrors.163.com/ubuntu/ lucid-updates universe main multiverse restricted #官方的Ubuntu 10.10要保留几个用于紧急更新 deb http://security.Ubuntu.com/ubuntu maverick-security main restricted deb-src http://security.Ubuntu.com/ubuntu maverick-security main restricted deb http://security.Ubuntu.com/ubuntu maverick-security universe deb-src http://security.Ubuntu.com/ubuntu maverick-security universe deb http://security.Ubuntu.com/ubuntu maverick-security multiverse deb-src http://security.Ubuntu.com/ubuntu maverick-security multiverse