问题补充：
Spelling Bee is a contest competitors, usually children, are asked to spell as many words as possible.
A. which
B. where
C. what
D. when
答案：
A. which
(答案→)B. where
C. what
D. when
解析：考查定语从句：先行词是a contest，定语从句中不缺主宾表，缺少地点状语，用关系副词where引导定语从句，句意：Spelling Bee是个参与者，通常是儿童，被要求尽可能多的拼写单词的比赛。选B。
