Ubuntu 出现apt-get: Package has no installation cand

今天在安装软件的时候出现了Package has no installation candidate的问题，如：

#  apt-get install <packagename>

Reading package lists... Done

Building dependency tree... Done

Package aptitude is not available, but is referred to by another package.

This may mean that the package is missing, has been obsoleted, or

is only available from another source

E: Package <packagename> has no installation candidate

解决方法如下：
# apt-get update
# apt-get upgrade
# apt-get install <packagename>

这样就可以正常使用apt-get了～

添加第三方地址：

sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"

sudo apt-get update