我使用了软件更新程序，最后它说
无法下载存储库信息
检查你的互联网连接
我看到一篇文章说使用sudo apt-get update
我试过了，它说
Ign:1 cdrom://Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725) bionic InRelease
Err:2 cdrom://Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725) bionic Release
Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
Hit:3 http://mirror.ehost.vn/ubuntu bionic InRelease
Hit:4 http://mirror.ehost.vn/ubuntu bionic-updates InRelease
Hit:5 http://mirror.ehost.vn/ubuntu bionic-backports InRelease
Hit:6 http://mirror.ehost.vn/ubuntu bionic-security InRelease
Hit:7 http://archive.canonical.com/ubuntu bionic InRelease
Reading package lists... Done
E: The repository 'cdrom://Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725) bionic Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
我还看到一个帖子说我应该去设置并选择选择最佳服务器在下载自在里面Ubuntu 软件标签。
然而，当我关闭该窗口时，出现了这样的情况：
我按下了Reload，它运行了缓存更新，但当它完成时，它又说
无法下载存储库信息
检查你的互联网连接细节
E:The repository 'cdrom://Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725) bionic Release' does not have a Release file.
我的网络完全没问题。