Technology has quickened the rate we communicate with the world around us.A. for which B.

问题补充：

Technology has quickened the rate we communicate with the world around us.

A. for which

B. at which

C. to which

D. with which

答案：

A. for which

(答案→)B. at which

C. to which

D. with which

解析：句意：技术加快了速度，我们以这种速度与我们周围的世人进行交流。这里是定语从句，先行词是rate，以rate连用的是介词at，which在从句中作介词的宾语，故选B。