/etc/apt/sources.list
1 2 3 4  | deb http://http.us.debian.org/debian/ testing non-free contrib main #deb http://http.us.debian.org/debian/ stable non-free contrib main #deb http://http.us.debian.org/debian/ unstable non-free contrib main #deb http://http.us.debian.org/debian/ wheezy non-free contrib main  | 
1 2  | #apt edit-sources
apt update | 
NO_PUBKEY 04EE7237B7D453EC NO_PUBKEY 648ACFD622F3D138
1 2  | apt-key adv --keyserver keyserver.ubuntu.com --recv 04EE7237B7D453EC apt-key adv --keyserver keyserver.ubuntu.com --recv 648ACFD622F3D138  | 
ubuntu repo names
1 2 3  | wheezy: debian 7.0 xenial: Ubuntu 16.04 focal: Ubuntu 20.04  | 
refer to:
https://serverfault.com/questions/550855/how-to-add-debian-testing-repository-to-apt-get
https://yunwei365.blog.csdn.net/article/details/114930145