  
             : Alt+F2,  : ubiquity          Alt+F1,   System Administration                                       options     Shift and Tab          3                                        Alt+F,                                               20                                        Ctrl+Alt+T  : sudo update-grub         (Alt+F4        shift             5  6                

        :
 Ctrl+Alt+T  sudo dpkg-reconfigure tzdata                  System > Administration               Alt+R.     the Install/Remove Languages              3                                Apply                 Ctrl+Alt+Backspace) 

  :
                               Ctrl+Alt+T : apt-get update'        'sudo apt-get install nameofpackage'.     : 'sudo apt-get remove nameofpackage'..
                                                           