firn ice

例句：

1. 1. The firn ice on the mountain is a wonder to behold.
   山上的冰原是一种令人惊叹的景象。
2. 2. The firn ice was formed from years of snowfall.
   这些冰是由多年的降雪形成的。
3. 3. The firn ice was so thick that it could not be penetrated by a knife.
   这些冰太厚了，连刀都切不进去。