Comparison may make something appear more beautiful than it is when alone.
A. to see
B. seeing
C. is seen
D. seen
网友回答
A. to see
B. seeing
C. is seen
(答案→)D. seen
解析：考查省略。当状语从句的主语与主句主语一致的时候，可以把状语从句的主语和be动词一起省略。本句在when于seen之间省略了something is。且something与see构成被动关系，使用过去分词的形式。故D正确。