Is the predicate of everyone singular or plural? Why?

Is the predicate of everyone singular or plural? Why?

If everyone is ready, we'll begin.Where Is everyone? But everyone can be replaced by plural pronouns. Pronouns are not predicates! Has everyone finished their drinks? Singular has is only used in very formal cases

Countable noun or uncountable noun after a little, less

Uncountable noun

On the quantifier Ge in modern Chinese
The difference between "one week" and "one week", "one hour" and "one hour"
Why can't we say "one second", "one minute", "one day" and "one year"

Week and hour are time nouns, so they can be omitted or not
Second, minute, day and year are quantifiers