25.In my opinion,life in the twenty-first century is much easier than ________.

问题描述:

25.In my opinion,life in the twenty-first century is much easier than ________.
A.that used to be B.it is used to C.it was used to D.it used to be
为什么不选A,that不也可指代么?

惯用法,it用作指代比较多, that 则多用作连接词