问题补充：
The visitor asked to have his picture taken stood the famous tower.
A. that
B. at which
C. when
D. where
答案：
A. that
B. at which
C. when
(答案→)D. where
解析：where 表示“在……的地方”，用以引导地点状语从句。注意，此题还涉及倒装，即此句的主语是 the famous tower，谓语是 stood，正常词序为 where the famous tower stood，使用倒装是为了保持句子平衡，避免头重脚轻。
