Contrast may make something appear more beautiful than it is when ______ alone.A seenB is seenC to be seenD having been seen
问题描述：
Contrast may make something appear more beautiful than it is when ______ alone.
A seen
B is seen
C to be seen
D having been seen
答
A 其他的都是错的
答
C to be sth
答
Contrast may make something appear more beautiful than it is when ______ alone.
A seen
B is seen
C to be seen
D having been seen
选A.
when seen alone是when it is seen alone(当单独被看时)的缩略.
全句的意思:
对比(的手段)使得某事物比单独看它时更加美丽.