ubuntu 镜像站点上尚不存在适用于 Ubuntu Xenial (16.04) 的 R 3.5.0 安装包。是否有其他方法可以在 ubuntu xenial 上将 R 更新到 3.5.0？或者，是否有不同的方法将 R 更新到 3.5.0？
我最近从 Ubuntu 16.04 升级到 18.04。现在，当我运行时apt-get upgrade，出现以下错误。
larry@VUbuntu15:~$ sudo apt-get upgrade
[sudo] password for larry:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
linux-generic linux-headers-generic linux-image-generic
The following packages will be upgraded:
libvte-2.91-0 linux-libc-dev
2 upgraded, 0 newly installed, 0 to remove and 3 not upgraded.
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