软件包没有安装候选项是什么意思？

Question

我试图在 ubuntu 中安装无线工具

 sudo apt-get install wireless-tools

当我按下回车键时它显示如下

Reading package lists... Done

Building dependency tree

Reading state information... Done

Package wireless-tools 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 'wireless-tools' has no installation candidate

帮我解决这个问题

Answer 1

在终端运行中software-properties-gtk查看是否选择了下图所示的选项。