Such a book ______ you showed me is difficult to understand.

问题描述:

Such a book ______ you showed me is difficult to understand.
答案到底是什么?

答案是as,不是that.
such...as用于引导定语从句,such...that 用于引导结果状语从句.
试比较:
He is such a good teacher as we all respect.他是一位我们大家都尊敬的好老师.(as引导的是定语从句,as 在该定语从句中用作respect的宾语)
He is such a good teacher that we all respect him.他是那样一位好老师,以致于我们大家都尊敬他.(that 引导的是结果状语从句,that在该状语从句中不充当句子成分,另外注意句中的respect带有宾语him)