IE不支持查找跨行文本？该怎么处理

IE不支持查找跨行文本？
环境：VS2005 C# XP

C# code

            mshtml.IHTMLDocument2 document = (mshtml.IHTMLDocument2)webbrowser1.Document.DomDocument;            IHTMLBodyElement body = (IHTMLBodyElement)document.body;            IHTMLTxtRange searchRange = (IHTMLTxtRange)body.createTextRange();            //......            string find = searchRange.text.Substring(x, y);                       if (searchRange.findText(find, 0, 0))            {                searchRange.select();            }