Solve Unment dependencies under ubuntu

Problem introduction##

# apt install libcurl3
Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 virtualbox-6.0: Depends:libfontconfig1(>=2.11.94) but it is not going to be installed
     Depends: libgl1-mesa-glx but it is not going to be installed or
       libgl1
     Depends:libice6(>=1:1.0.0) but it is not going to be installed
     Depends:libopus0(>=1.1) but it is not going to be installed
     Depends: libsdl1.2debian(>=1.2.11) but it is not going to be installed
     Depends: libsm6 but it is not going to be installed
     Depends:libvpx3(>=1.5.0) but it is not going to be installed
     Depends: libx11-xcb1 but it is not going to be installed
     Depends:libxcursor1(>1.1.2) but it is not going to be installed
     Depends: libxmu6 but it is not going to be installed
     Depends: libxrender1 but it is not going to be installed
     Depends: libxt6 but it is not going to be installed
     Recommends: libasound2
     Recommends: libpulse0 but it is not going to be installed
     Recommends: libsdl-ttf2.0-0 but it is not going to be installed
     Recommends: gcc but it is not going to be installed
     Recommends: make or
        build-essential but it is not going to be installed or
        dpkg-dev but it is not going to be installed
     Recommends: binutils but it is not going to be installed
     Recommends: pdf-viewer
     Recommends: libgl1
E: Unmet dependencies. Try 'apt-get -f install'with no packages(or specify a solution).

The reason for this problem is that under Ubuntu, for example, Ubuntu 14.04 or 16.04 generally does not appear broken dependencies, or unmet dependencies, but if we use dpkg to forcibly install certain deb packages, or whether in build-dep When you manually change the files and versions of some Packages, the problems mentioned above may occur when you use apt-get install or build-dep to install the packages again.

Solution##

We can execute the command according to the prompt, if the problem remains the same, then we try to execute the command

first step

sudo apt-get-f install
sudo apt-get update
sudo apt-get upgrade

second step

sudo apt-get update
sudo apt-get clean
sudo apt-get autoremove

third step

sudo apt --fix-broken install
sudo apt-get update && sudo apt-get upgrade
sudo dpkg --configure -a
sudo apt-get install -f

After performing the above steps, basically the problem can be solved