Which three statements are true about multiple-row subqueries? (Choose three.)
A. They can contain a subquery within a subquery.
B. They can return multiple columns as well as rows.
C. They cannot contain a subquery within a subquery.
D. They can return only one column but multiple rows.
E. They can contain group functions and GROUP BY and HAVING clauses.
F. They can contain group functions and the GROUP BY clause, but not the HAVING clause
关于B选项，select a.id form (select id,sale from sale) a 成立，所以B对D错。
原文：http://www.cnblogs.com/Babylon/p/7928715.html