To not be able to distinguish the top from the bottom
To be about the same; to have a very small difference
Neutral
None
None
This is an HSK chengyu
《蠹化》(Dù Huà), a work by Táng Dynasty (唐, 618 - 907) poet 陆龟蒙 (Lù Guī Méng)
This chengyu is from a line in the work listed in the "Origin" section above