code: public String[][] getEdgeArray()
      {
          String[][] edge = new String[word.length + 1][word.length + 1];
          for (CoNLLWord coNLLWord : word)
          {
              edge[coNLLWord.ID][coNLLWord.HEAD.ID] = coNLLWord.DEPREL;
          }
  
          return edge;
      }
docs: 获取边的列表，edge[i][j]表示id为i的词语与j存在一条依存关系为该值的边，否则为null
  @return