题目内容：

one of which is that.表示不懂.

优质解答

one of which 是主语部分,is系动词（be 动词在句子中单独作为谓语动词时,be动词为系动词,其后为表语）,that从句是表语.
one of which中one 是句子的主语,of which是one的定语.