begin
  if OpenDialog1.Execute then
    begin
      if ExtractFileExt(OpenDialog1.FileName)='.jpg' then
        ShowMessage('您開啟的是Jpeg形態檔案')
      else
      if ExtractFileExt(OpenDialog1.FileName)='.doc' then
        ShowMessage('您開啟的是Word形態檔案')
      else
        ShowMessage('其它形態檔案');
    end;
end;