from the top of the tower ,the south foot of the mountain is a sea of trees.
A. Seen
B. Seeing
C. Having seen
DTo see
网友回答
(答案→)A. Seen
B. Seeing
C. Having seen
D. To see
解析：句意为：从塔顶往下看，南边的山脚下是一片树的海洋。本题考查分词作状语。分词作状语，其逻辑主语与句子主语一致。主语the south foot of the mountain 与see 在逻辑上为被动关系，四个选项中只有A项表被动。