The time is not far awaymodern communications will become widespread in China’s vast count

问题补充：

The time is not far awaymodern communications will become widespread in China’s vast countryside.

A. as

B. until

C. before

D. when

答案：

A. as

B. until

C. before

(答案→)D. when

解析：句子可改为：The time when modern communications will become widespread in China’s vast countryside. when引导定语从句。