Question

in my opinion life in the 21st century is much easier than（）

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？请解释，谢谢 我学比较级的时候用来代指天气等不可数名次都用that啊 ！！！ 怎么这个不是呢》？

Answer 1

应该选D吧！
因为指代的东西是前面提到的“life”,是已经确定的