Question

In my opinion, life in the twenty-first 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

答案 D 为什么不选A
为什么上题用it
The weather in Beijing is colder than that in Hunan. 这个就用 that？

Answer 1

it 是同物所指，指“life” (生活只是过去和现在有所不同, 指代同一物体）
如：----Do you want the magazine？
----Yes, I want it.（指的就是上面的magazine）
而that代替“the weather”指代另外一个地区的天气，不是同一物体。

Answer 2

IT 指代life in the 21century