回複:could you be a little more specific, please?
please see old posts of 北京二號 on pronunciation and her blog
e.g.
http://web.wenxuecity.com/BBSView.php?SubID=mysj&MsgID=84010
http://web.wenxuecity.com/BBSView.php?SubID=mysj&MsgID=84358
these are excellent.