What is the pronunciation of "Zhan" for "mouth is necessary"?

Read the first sound zhān for the following reasons:

First of all, the fourth sound zhàn has two meanings: one is to occupy; Being in a specific position or belonging to a specific situation. It is obviously far-fetched to explain "mouth-holding stunt" with these two meanings. ?

Secondly, the meaning of the first sound zhān has another meaning besides the surname: divination. It seems meaningless to use this meaning, but after careful analysis, it is not like this. Phrases in this sense include: divination, quasi-occupation, dream occupation, etc. Ancient people recited poems, dictated words, and divination, both in expression and tone. Therefore, it is more appropriate to read "oral occupation (zhān) is necessary".