I meet lots of problems when i installed and use ubuntu 16.04.below is my using note:
(my operating system is english, so i use english and let this as an exerices.: )
Open Terminal Window and input command of su,then input the pass, but is return an error : su:Authentication failure.
the resolution is input command:sudo passwd root and input the new pass.then ur can resolve it.
use command : apt-get update then apt-get upgrade
It maybe useing half an hour to get info and soft from internet.
原文：http://www.cnblogs.com/veviDP/p/6821518.html