mountainousness

例句：

1. 1. The area is famous for its mountainous landscape.
   该地区以其山区景观而闻名。
2. 2.The hikers were exhausted after a day of mountainous hiking.
   徒步旅行者在一天的山区徒步后筋疲力尽。
3. 3. The mountainous terrain made it difficult to navigate the area.
   山区地形使得该区域难以导航。