We had five degrees of frost last night. 昨晚零下5度。

degrees 是“度数”；frost是“冰点”。degrees of frost： 是“冰点以下的度数”。该词组本身就表示“冰点以下”，所以，of不宜换成below。如果把frost改为zero，则要用below，如：five degrees below zero。

We're going to have 10 degrees of frost.

气温将从冰点下降到10度。

Fifty degrees below zero meant eighty-odd degrees of frost.

零下五十度相当于冰点以下八十多度。

There was 5 degrees of frost last night. 

昨晚气温为零下五度。

The thermometer registered four degrees of frost. 

温度计指着零下四度。

Ten degrees of frost had frozen the lock on the car. 

零下十摄氏度把轿车上的锁冻住了。