A.Subqueries can contain GROUP BY and ORDER BY clauses 
B.Main query and subquery can get data from different tables 
C.Main query and subquery must get data from the same tables 
D.Subqueries can contain ORDER BY but not the GROUP BY clause 
E.Only one column or expression can be compared between the main query and subquery
F. Multiple columns or expressions can be compared between the main query and subquery