今天早上我醒来时，地面上覆盖着一层霜。

When I woke up this morning, the ground was covered with ___frost.

昨晚有一场严酷的霜冻，损坏了庄稼。

Last night, there was a hard ___frost that damaged the crops.

在这个温室里，植物免受霜冻和其他寒冷天气的影响。

In this greenhouse, plants are safe from ___frost and other cold weather.