code: public CoNLLWord[] getWordArrayWithRoot()
      {
          CoNLLWord[] wordArray = new CoNLLWord[word.length + 1];
          wordArray[0] = CoNLLWord.ROOT;
          System.arraycopy(word, 0, wordArray, 1, word.length);
  
          return wordArray;
      }
docs: 获取包含根节点在内的单词数组
  @return