所以我有python 3.8和pip，但我也想安装稳定的python 3.7和pip。但是当我尝试
sudo apt-get install python3.7
它说该软件包不可用，但被称为另一个软件包。
请帮忙
错误：
Reading package lists... Done
Building dependency tree
Reading state @R_206_4045@ion... Done
Package python3.7 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 'python3.7' has no installation candidate
