Nginx下Whmcs的伪静态规则如下，直接放到server标签中即可。

server
        {
.........
# Announcements
rewrite ^/announcements/([0-9]+)/[a-zA-Z0-9_-]+.html$ /announcements.php?id=$1 last;
rewrite ^/announcements$ /announcements.php last;

# Downloads
rewrite ^/downloads/([0-9]+)/([^/]*)$ /downloads.php?action=displaycat&catid=$1 last;
rewrite ^/downloads$ /downloads.php last;

# Knowledgebase
rewrite ^/knowledgebase/([0-9]+)/[a-zA-Z0-9_-]+.html$ /knowledgebase.php?action=displayarticle&id=$1 last;
rewrite ^/knowledgebase/([0-9]+)/([^/]*)$ /knowledgebase.php?action=displaycat&catid=$1 last;
rewrite ^/knowledgebase$ /knowledgebase.php last;
.........
}