如果一个查询的数据源仍是查询，而不是表，则该查询称为______。
参考答案：子查询
腋杖步行方法包括（）
A、两点步行
B、三点步行
C、四点步行
D、迈至步
E、迈越步
.
Many scientists believe that now we can study the behavior of a three-year-old child to see ____ they
will grow up to be criminals.
A．that
B．how
C．why
D．whether
