ParserTreeViewer.ParsedCorpus.GetSentence C# (CSharp) Method

        public string GetSentence( int index )
        {
            if( corpus_rdr == null )
            corpus_rdr = new System.IO.FileStream( corpus_path, System.IO.FileMode.Open );

               corpus_rdr.Position = sent2pos[index];

               // Загружаем текст предложения внутри узла <text>...</text>

               ReadLine( corpus_rdr ); // пропускаем тег <sentence...>
               string text_xml = ReadLine( corpus_rdr );

               if( text_xml.StartsWith( "<text>" ) && text_xml.EndsWith( "</text>" ) )
               {
            return text_xml.Substring( 6, text_xml.Length - 6 - 7 );
               }
               else
               {
            return "";
               }
        }

        private void listView1_RetrieveVirtualItem(object sender, RetrieveVirtualItemEventArgs e)
        {
            string sent = parsed_corpus.GetSentence(e.ItemIndex);

            e.Item = new ListViewItem(sent);
            return;
        }