Which two statements are true regarding views?（）

• A、A subquery that defines a view cannot include the GROUP BY clause 
• B、A view that is created with the subquery having the DISTINCT keyword can be updated 
• C、A view that is created with the subquery having the pseudo column ROWNUM keyword cannot be updated 
• D、A data manipulation language (DML) operation can be performed on a view that is created with the subquery having all the NOT NULL columns of a table