当我运行时sudo，终端卡住了几秒钟，然后输出错误消息。我的终端看起来像这样：
ubuntu@(none):~$ sudo true
sudo: unable to resolve host (none)
我能做些什么来解决它？
Err http://archive.canonical.com natty InRelease
Err http://security.ubuntu.com oneiric-security InRelease
Err http://extras.ubuntu.com natty InRelease
Err http://security.ubuntu.com oneiric-security Release.gpg
Temporary failure resolving ‘security.ubuntu.com’
Err http://archive.canonical.com natty Release.gpg
Temporary failure resolving ‘archive.canonical.com’
Err http://extras.ubuntu.com natty Release.gpg
Temporary failure resolving ‘extras.ubuntu.com’
Err http://gb.archive.ubuntu.com oneiric InRelease
Err http://gb.archive.ubuntu.com oneiric-updates InRelease
Err http://gb.archive.ubuntu.com natty-backports InRelease
Err http://gb.archive.ubuntu.com oneiric Release.gpg
Temporary failure resolving ‘gb.archive.ubuntu.com’
Err http://gb.archive.ubuntu.com oneiric-updates Release.gpg
Temporary failure resolving ‘gb.archive.ubuntu.com’
Err http://gb.archive.ubuntu.com natty-backports Release.gpg
Temporary failure resolving ‘gb.archive.ubuntu.com’
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