"Lotus leaf lotus root" is a dual-purpose word of lotus, which is actually "lotus leaf lotus root".
"Fog dew frost" is a dual-purpose word to describe the five states of the atmosphere, which is actually "fog dew frost".
The rhyme of this couplet is:
Part I: Pingwa Pingwa
Bottom line: flat and faint.
This is a long-standing isolated couplet, which requires not only word-to-word, but also external and even right. The dual use of alto is the difficulty of this connection.