Have some packages to be installed, if you use is unstable distribution, this perhaps is
Because the system can not meet your requirements of the state, there may be some you need in this version of the software
Package has not yet been created, or they have been from new to (Incoming) directory,
The following information may help solve the problem:

The following packages have unmet dependency:
Ros - melodic - desktop - full: rely on: ros - melodic - desktop but it will not be installed
Rely on: ros - melodic - perception but it will not be installed
Rely on: ros - melodic - simulators but it will not be installed
Rely on: ros - melodic - urdf - sim - tutorial but it will not be installed
E: unable to correct mistakes, because you asked to keep the status quo, some software packages is that they destroyed the dependence of software compartment,