In this kind of____weather,the ice in the river must be____(freeze)

问题描述:

In this kind of____weather,the ice in the river must be____(freeze)

freezing; frozen前面一个我懂了,后面一个是为什么捏?
我们老师说frozen是冷藏的,速冻的,如:frozen food第二空是被动语态, 指河面“被冻了”“结冰了”
被动语态的基本形式是“be+ 过去分词”