difficulty index

例句：

1. 1.The difficulty index of the task is high, requiring more time and effort.
   这项任务的困难指数很高，需要更多的时间和努力。
2. 2.The difficulty index of the problem has increased significantly.
   这个问题的困难指数已经显著增加。
3. 3.To improve efficiency, we need to reduce the difficulty index of our work.
   为了提高效率，我们需要降低我们工作的难度指数。