我想安装 virtualbox，我必须安装 virtualbox -qt，但软件包出现了问题
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:
virtualbox : Depends: libgsoap-2.8.91 but it is not installable
Depends: libsdl1.2debian (>= 1.2.11) but it is not installable
Depends: libvncserver1 (>= 0.9.10) but it is not installable
Recommends: virtualbox-qt (= 6.1.6-dfsg-1) but it is not going to be installed
Recommends: libqt5opengl5 (>= 5.0.2) but it is not installable
E: Unable to correct problems, you have held broken packages.'''
帮我解决 Ubuntu 20.04 上的这个问题
输出apt policy virtualbox-qt：
bogdan@bogdanbook:~$ apt policy virtualbox-qt
virtualbox-qt:
Installed: (none)
Candidate: 6.1.6-dfsg-1
Version table:
6.1.6-dfsg-1 500
500 archive.ubuntu.com/ubuntu focal/multiverse amd64 Packages