ultracold

例句：

1. 1. The scientist found the temperature to be ultracold.
   科学家发现温度极其低。
2. 2. The ice was so ultracold that it could not support any weight.
   冰非常冷，无法承受任何重量。
3. 3. The polar bears were forced to migrate due to the extreme cold in their habitat.
   由于栖息地的极端寒冷，北极熊被迫迁移。