无法安装 mysqli 扩展，使用 php 7.2

问：

我现在使用的是 linux mint、apache2、mySQL 5.7、php 7.2。

我试图在我的本地服务器上执行基本的php登录网页，这是 http://192.168.xxx.xxx/ 但是当我登录我的页面时，总是出现白色页面。

我尝试安装php mysqli扩展，所以我在终端上编写了如下命令：

taylor@C10ud-9 ~ $ sudo apt-get install php-mysql
Reading package lists... Done
Building dependency tree       
Reading state information... Done
php-mysql is already the newest version (1:7.0+35ubuntu6.1).
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
taylor@C10ud-9 ~ $ sudo apt-get install php-mysqlnd
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Note, selecting 'php7.0-mysql' instead of 'php-mysqlnd'
php7.0-mysql is already the newest version (7.0.25-0ubuntu0.16.04.1).
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
taylor@C10ud-9 ~ $ sudo apt-get install php7.0-mysql
Reading package lists... Done
Building dependency tree       
Reading state information... Done
php7.0-mysql is already the newest version (7.0.25-0ubuntu0.16.04.1).
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
taylor@C10ud-9 ~ $ phpenmod mysqli
WARNING: Module mysqli ini file doesn't exist under /etc/php/7.2/mods-available
WARNING: Module mysqli ini file doesn't exist under /etc/php/7.2/mods-available

但是找不到 mysqli。