docs: protected IWord getNextPunctuationPairWord(int c, int pos) throws IOException
      {
          IWord w = null, w2 = null;
          String text = getPairPunctuationText(c);
          
          //handle the punctuation.
          String str = String.valueOf((char)c);
          if ( ! ( config.CLEAR_STOPWORD 
                  && dic.match(ILexicon.STOP_WORD, str) ) ) {
              w = new Word(str, IWord.T_PUNCTUATION);
              w.setPartSpeech(IWord.PUNCTUATION);
              w.setPosition(pos);
          }
          
          //handle the pair text.
          if ( text != null && text.length() > 0
                  && ! ( config.CLEAR_STOPWORD 
                          && dic.match(ILexicon.STOP_WORD, text) ) ) {
              w2 = new Word( text, ILexicon.CJK_WORD );
              w2.setPartSpeech(IWord.PPT_POSPEECH);
              w2.setPosition(pos+1);
              
              if ( w == null ) w = w2;
              else wordPool.add(w2);
          }
          
          /* here: 
           * 1. the punctuation is clear.
           * 2. the pair text is null or being cleared.
           * @date 2013-09-06
          */
          if ( w == null && w2 == null ) {
              return null;
          }
          
          return w;
      }