from the top of the hill the town looks like a diamond.A. Having seenB. SeeingC. To see

问题补充：

from the top of the hill, the town looks like a diamond.

A. Having seen

B. Seeing

C. To see

D. Seen

答案：

A. Having seen

B. Seeing

C. To see

(答案→)D. Seen

解析：考查分词做状语。分词做状语时，如果动词与句子主语构成主动关系，使用现在分词形式；如果构成被动语态，使用过去分词的形式。本题the town与see构成被动关系，故使用过去分词的形式。句意：从山顶上看，这个城镇看起来像钻石。故D正确。