Ubuntu/Linux 新手，遇到问题。我正在尝试在 18.04.1 Bionic Beaver 上设置 NordVPN，并尝试使用此处网站上的 4 个安装步骤：
https://nordvpn.com/download/linux/
...当我运行第一个命令时，出现此错误：
sudo apt-get install /home/ubuntu/Downloads/nordvpn-release_1.0.0_all.deb
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'nordvpn-release' instead of '/home/ubuntu/Downloads/nordvpn-release_1.0.0_all.deb'
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 resolve the situation: …