I donot think more A,B two separate primary key can be accepted by single entity.
Though according to ur question , I could say
as, AB primary key ,closure of AB could accept all other attributes
So, in 1NF (ABCDEF) - could accept in 1 table.
In case of 2NF , 3NF , 4NF there are 3 tables.
One table for X and other 2 tables for E and F
In case of BCNF , each attribute should be a super key.
So, In that case table could be more.
But in general there could be only 3 tables