直接翻译你的要求重写规则：

Directly translating your requirements to rewrite rules:

RewriteEngine On
RewriteCond %{QUERY_STRING} ^mod=(.*)$
RewriteRule ^$ %1

但你可能想要的东西更灵活，如：

But you probably want something more flexible like:

RewriteEngine On
RewriteCond %{QUERY_STRING} (?:^|&)mod=([^&]+)
RewriteRule /?(.*) %1/$1 [QSA]

这些规则适用于你的域的根。

These rules apply to the root of your domain.

如果你想要做一个外部重定向添加研究标志重写规则。

If you want to do an external redirect add the R flag to the rewrite rule.