我需要 gcc-6 和 g++-6 来编译一个特定的程序（与 CUDA 相关），我尝试遵循这些说明但由于某些原因，我得到以下信息：
> sudo apt-get install gcc-6 g++-6 -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package gcc-6 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
Package g++-6 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 'gcc-6' has no installation candidate
E: Package 'g++-6' has no installation candidate
有没有简单的方法来安装这些版本的 gcc 和 g++？
提前致谢。