sudo apt-get install python-virtualenv

在阿里云ubuntu系统下执行命令。出现下列提示是什么意思。同样的命令在vm虚拟机ubuntu系统可以执行的。请指点

Reading package lists... Done
Building dependency tree
Reading state information... Done
Package python-virtualenv 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 'python-virtualenv' has no installation candidate


执行卸载包
sudo apt-get install python-virtualenv
出现提示

Reading package lists... Done
Building dependency tree
Reading state information... Done
Package 'python-virtualenv' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
请指点要怎么做才能解决问题，谢谢