我安装了 Virtualbox 5.0，但每次启动虚拟机时我都必须执行以下命令：
sudo /sbin/rcvboxdrv setup
所以我决定删除 Virtualbox 并为 Ubuntu 16.04 安装 5.1 版本。这是一个糟糕的决定。我无法让它工作。
$ sudo dpkg -i virtualbox-5.1_5.1.8-111374~Ubuntu~xenial_amd64.deb
Selecting previously unselected package virtualbox-5.1.
(Reading database ... 814705 files and directories currently installed.)
Preparing to unpack virtualbox-5.1_5.1.8-111374~Ubuntu~xenial_amd64.deb ...
Unpacking virtualbox-5.1 (5.1.8-111374~Ubuntu~xenial) ...
dpkg: dependency problems prevent configuration of virtualbox-5.1:
virtualbox-5.1 depends on libqt5x11extras5 (>= 5.1.0); however:
Package libqt5x11extras5 is not installed.
$ sudo apt install libqt5x11extras5
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libqt5x11extras5 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'libqt5x11extras5' has no installation candidate
如何在 Ubuntu 16.04 上安装 Virtualbox 5.1？