code: public QuestionStructure getMainPart(String question, String questionWords) {
          List<edu.stanford.nlp.ling.Word> words = new ArrayList<>();
          String[] qw = questionWords.split("\\s+");
          for (String item : qw) {
              item = item.trim();
              if ("".equals(item)) {
                  continue;
              }
              words.add(new edu.stanford.nlp.ling.Word(item));
          }
          return getMainPart(question, words);
      }
docs: 获取句子的主谓宾
  
  @param question 问题
  @param questionWords 问题词序，相互之间以空格分割
  @return 问题结构