我只是做了一个do-release-upgrade，效果很好，但是自运行以来我一直停留在php7.3上
apt install php7.4
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
php7.4 : Depends: libapache2-mod-php7.4 but it is not going to be installed or
php7.4-fpm but it is not going to be installed or
php7.4-cgi but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
有趣的是，并不是所有的PHP 7.4都可以在APT中使用
dpkg -l | grep php7.4
返回
ii php7.4-bcmath 7.4.5-1+ubuntu19.10.1+deb.sury.org+1 amd64 Bcmath module for PHP
ii php7.4-common 7.4.5-1+ubuntu19.10.1+deb.sury.org+1 amd64 documentation, examples and common module for PHP
ii php7.4-sqlite3
没有删除ppa ondrej，apt清理，更新/升级，apt install -f没有成功。
知道会是什么吗？
