在安装时出现如下报错：
The following packages have unmet dependencies:
gnome-user-docs-zh-hans : Depends: gnome-user-docs (= 3.28.1-0ubuntu1) but 3.28.2+git20180715-0ubuntu0.1 is to be installed
原因是系统中已经安装的gnome-user-docs与要求的版本不一样。
解决办法：
在termial终端中，将gnome-user-docs卸载后，重新安装，系统会自动安装正确的版本。
sudo apt-get remove gnome-user-docs
sudo apt-get install gnome-user-docs
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https://askubuntu.com/questions/824437/how-to-install-language-support-completely-using-command-line
sudo apt install $(check-language-support)