我无法安装 php7.0-mbstring：
以下软件包具有未满足的依赖关系： php7.0-mbstring ：依赖：php7.0-common (= 7.0.19-1) 但要安装 7.0.20-1~dotdeb+8.2 E: 无法纠正问题，您持有破损的包裹。
来源.列表：
deb http://debian.man.ac.uk/debian/ stretch main deb-src http://debian.man.ac.uk/debian/ stretch main
deb http://security.debian.org/ stretch/updates main contrib deb-src http://security.debian.org/ stretch/updates main contrib
deb http://ftp.at.debian.org/debian/ stretch-updates main contrib non-free deb-src http://ftp.at.debian.org/debian/ stretch-updates main contrib non-free
deb http://download.webmin.com/download/repository sarge contrib
apt-cache policy输出：
Package files:
100 /var/lib/dpkg/status
release a=now
500 http://download.webmin.com/download/repository sarge/contrib amd64 Packages
release v=3.1,o=Jamie Cameron,a=stable,n=sarge,l=Webmin,c=contrib,b=amd64
origin download.webmin.com
500 http://ftp.at.debian.org/debian stretch-updates/main amd64 Packages
release o=Debian,a=stable-updates,n=stretch-updates,l=Debian,c=main,b=amd64
origin ftp.at.debian.org
500 http://security.debian.org stretch/updates/contrib amd64 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=contrib,b=amd64
origin security.debian.org
500 http://security.debian.org stretch/updates/main amd64 Packages
release v=9,o=Debian,a=stable,n=stretch,l=Debian-Security,c=main,b=amd64
origin security.debian.org
500 http://debian.man.ac.uk/debian stretch/main amd64 Packages
release v=9.3,o=Debian,a=stable,n=stretch,l=Debian,c=main,b=amd64
origin debian.man.ac.uk
apt-cache policy php7.0-common输出：
Installed: 7.0.20-1~dotdeb+8.2
Candidate: 7.0.20-1~dotdeb+8.2
Version table:
*** 7.0.20-1~dotdeb+8.2 100
100 /var/lib/dpkg/status
7.0.19-1 500
500 http://debian.man.ac.uk/debian stretch/main amd64 Packages
答案1
您有一个来自 dotdeb 的版本php7.0-common，您的存储库列表不再了解该版本，并且它阻止您安装 Debian 9 PHP 软件包。您应该删除它以及依赖它的任何软件包，并php7.0-common从 Debian 存储库安装：
sudo apt remove php7.0-common
sudo apt install php7.0-mbstring