firn的用法和样例：
例句
用作名词 (n.)
- Snow has lasted for several days in many districts and the firn is considered as the most serious one during the last 50 years.
在许多地区，大雪已连续下了很多天，积雪被称为五十年来最严重的一次。
词汇搭配
- iced firn 冻结粒雪
- firn snow 陈雪,粒雪
- firn limit 雪线
- ice firn 冻粒雪
- firn line 永久雪线,粒雪线...
- firn basin 粒雪盆地
- firn field 永久积雪原
