code: public List<CoNLLWord> findChildren(CoNLLWord word, String relation)
      {
          List<CoNLLWord> result = new LinkedList<CoNLLWord>();
          for (CoNLLWord other : this)
          {
              if (other.HEAD == word && other.DEPREL.equals(relation))
                  result.add(other);
          }
          return result;
      }
docs: 找出特定依存关系的子节点
  @param word
  @param relation
  @return