There are no easy answers to questions brought to us by the rapidly changing world we can

问题补充：

There are no easy answers to questions brought to us by the rapidly changing world, we can try to turn challenges into opportunities．

A. so

B. but

C. for

D. then

答案：

A. so

(答案→)B. but

C. for

D. then

解析：考查连词：句意：对于快速变化的世界给我们带来的问题没有容易的答案，但是我们可以努力的把挑战变成机会。A．so因此，引导结果状语从句，B．but 但是，连接转折并列句，C．for并列连词，因为，D．then副词“然而”，选B。