问题 填空题

已知关系R(A,B,C),其中A,C为数值型属性,试用SQL语句完成:按属性A分组,求出每组中在属性C上的最大值和最小值,且将它们置于视图RVE中。
______
AS
______
FROMR
______;

答案

参考答案:SELECT A,MAX(C),MIN(C)

阅读理解

阅读理解。

     Linda used to wake you up on Sunday morning when you wanted to stay in bed, but now you will feel

strange if she gets up before lunch. She used to be very quiet, but now she talks all the time-but not to you.

She used to hold your hand when you went to visit your friends. Now she doesn't even want to be seen

with you when you go to visit your friends. Your Linda might spend hours on the phone or in the bathroom

now. At the same time John next the door has become quiet and dirty. He used to be very polite. Now a

simple conversation with John becomes very difficult. You've gone from heroes to the most embarrassing

adults in the world. Your child has become a teenager!

     What makes adolescence (青春期) so difficult? Physical and emotional (身体上和情感上的) changes

are the reasons that make them change so much. When the> are young, children live in a safe and simple

land called"childhood". Parents organize their lives. Parents choose children's clothes, take them to places,

and spend time with them. They're with the children when there is a problem. As children get older, however,

they learn about another land-an exciting land, called"adulthood". Sooner or later their hormones (荷尔蒙!)

change them. Adolescence, then, is the trip from childhood to adulthood. Some find the trip quite easy.

For others, it's very difficult.

1. The article is probably written about _________.

A. teachers

B. teenagers

C. parents

2. When Linda was a child, she didn't use to _________.

A. stay with her parents in public

B. get up early

C. spend hours on the phone

3. When your children get older and older, _________.

A. they like to talk to you

B. they hardly change

C. they change physically and emotionally

4. Why is Linda's adolescence so different from her childhood?

A. Because her teachers look at her differently.

B. Because the hormone in her body changes her.

C. Because parents look at her differently.

5. What is the best title for the passage?

A. The Changes from Childhood to Adolescence.

B. Linda and John.

C. Hormones.

判断题