Thanks for your great help.
The “align fbseocomments form center” code seems not working well. I’ll report you of what was wrong later.
A newer problem with the theme I found just now is:
-With the plugin SEO Facebook Comments installed, strangely, the Facebook comment frame on any page or post will only show once. In other words, when a user connects to my website http://eng-lish.net , no matter he/she chooses to read a page or a post, the fbseocomments frame works normally. But after their closing the first page/post, the fbseocomments frame will never shows on the following page/post. I thought the cause of the problem might be the “#” sign added to my domain name after first page/post read. Can this issue be repeated on your end? Please help to check. Thanks! 🙂