The following packages have unmet dependencies:
g++ : Depends: g++-7 (>= 7.4.0-1~) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
这个怎么弄呀
这个错误是因为您当前安装的g++版本过低，而您正在尝试安装的软件需要g++-7版本等于或高于7.4.0-1~, 因此您需要升级g++。