Choose two.
Which two statements are true about the DUAL table?
A) It can display multiple rows and columns.
B) It can be accessed only by the SYS user.
C) It can be accessed by any user who has the SELECT privilege in any schema
D) It can display multiple rows but only a single column.
E) It consists of a single row and single column of VARCHAR2 data type.
F) It can be used to display only constants or pseudo columns.
Answer：AC
(解析：dual 这个虚拟的表可以显示多行多列;任何用户都可以访问它。这道题的难点就是对 Answer：C 的理解：在任何模式中拥有 select 权限的用户都可以访问它。
每个用户的 select 权限是不需要单独给的，只要是自己的东西，自然就有 select 的权限。)