It is the low area between the lower lip and the chin... and in it you can read... nutrition problems and whether he can resist drinking.
A line, blank, or scar in CHENG JIANG means digestive problems such as food poisoning.
CHENG JIANG is low.. means that
The person does not have digestive problems and is likely to be a good drinker...on the other hand, a flat CHENG JIANG (compared to the lips and chin) means...the person gets drunk easily..