mark@mark-Inspiron-3847:~ $ sudo apt-cache policy gnome-shell
gnome-shell:
  Installed: 3.28.3-0ubuntu0.18.04.2
  Candidate: 3.28.3-0ubuntu0.18.04.2
  Version table:
 *** 3.28.3-0ubuntu0.18.04.2 500
        500 http://gb.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.28.1-0ubuntu2 500
        500 http://gb.archive.ubuntu.com/ubuntu bionic/main amd64 Packages