我按照以下说明在我的机器上安装 Emacs 24（借自：http : //www.mikeyboldt.com/2011/11/30/install-emacs-24-in-ubuntu/）：
sudo add-apt-repository ppa:cassou/emacs
sudo apt-get update
sudo apt-get install emacs-snapshot
但我收到以下错误：
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
emacs-snapshot : Depends: libgnutls26 (>= 2.12.6.1-0) but 2.10.5-1ubuntu3 …