In my opinion，life in the twenty－first century is much easier than .A. that used to beB. i

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

A. that used to beB. it is used toC. it was used to(答案→)D. it used to be解析：表示 “过去常常……”用“used to do”。本题中“be”为连系动词，不是实义动词，不能省略。

这个问题我还想问问老师呢