请组织一次大学生下基层（农村等）前的培训。

A. 准备工作
B. 资料整理
C. 初始地籍测量
D. 文字总结

A. The inner query always sorts the results of the outer query
B. The outer query always sorts the results of the inner query
C. The outer query must return a value to the outer query
D. The inner query returns a value to the outer query
E. The inner query must always return a value or the outer query will give an error