Finally he reached a lonely island was completely cut off from the outside world.A. whenB

问题补充：

Finally he reached a lonely island was completely cut off from the outside world.

A. when

B. where

C. which

D. whom

答案：

A. when

B. where

(答案→)C. which

D. whom

解析：考查定语从句：句意：最终他来到一个完全和外界隔绝的孤岛上。这是定语从句，先行词是a lonely island，定语从句中缺少主语，用which引导定语从句。选C。