从 16.04 build-essential、g++、gcc 和 cpp 升级到 Ubuntu 18.04 之后 E: Unable to correct problems, you have held broken packages.
$ sudo apt-get install build-essential
Reading package lists... Done
Building dependency tree
Reading state information... Done
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 …