problem tree的用法和樣例：
例句
- The concept, theory, characteristics, analytical steps, model structure of problem tree analysis and the importance in regional development planning were introduced in the paper.
本文介紹了問(wèn)題樹(shù)分析法的概念，理論要點(diǎn)，特點(diǎn)，分析步驟，模型結構及在區域發(fā)展研究中的重要性。
