使数据库表变为自由表的命令是【 】TABLE。

1980年，年龄在18岁到24岁之间，与父母生活在一起的人占该年龄段人口的比例为48%，而1986年，这一比例上升至53%。可以说，在1986年，这一年龄段的人更加难于负担独立生活。
上文得出的结论是基于下列哪项假设( )

A．这一年龄段中不能自立的人更愿意和同龄人生活在一起，而不是和父母
B．这一年龄段中有些人，只要他们能独立生活，就会选择独立，而不再和父母生活在一起
C．这一年龄段中与父母生活在一起的人，不分担房费支出
D．这一年龄段中有些人尽管在调查时和父母住在一起，而在此之前是独立生活的

阅读理解

     Robby was 11 when his mother dropped him off for his first piano lesson. I prefer students to begin

at an earlier age. Robby said that it had always been his mother's dream to hear him play the piano, so

I took him on as a student.

     Robby tried and tried while I listened and encouraged him and gave him more instructions. But he

just did not have any inborn ability.

     I only saw his mother from a distance. She always waved and smiled but never came in.  Then one

day Robby stopped coming to our lessons. I thought about calling him but I guessed he had decided to

try something else.

     I was also glad that he stopped coming for the sake of my career. However, several weeks before

the recital (演奏会) of my students, Robby came,telling me that he never stopped practicing and begged

me to allow him to take part in it. I agreed, but I made him perform last in the program, so I could save

his poor performance through my "curtain closer".

     I was surprised when he announced that he had chosen one piece of Mozart's. However, never had

I heard a piece of Mozart's played so well by someone at his age.

     I ran up and put my arms around Robby in joy. "I've never heard you play like that, Robby! How

could you do it?"

     "Well, Miss Hondorf. Do you remember I told you my mom was sick? Actually she died this

morning. She was born deaf, so tonight was the first time she could hear me play. I wanted to make it

special. I knew I could."

1. Why might Robby have stopped coming to piano lessons suddenly?

A. He lost heart and believed that he would never make it.

B. His mother might have been seriously ill.

C. He thought that his teacher disliked him.

D. His mother died and he didn't need to play any longer.

2. We can know from the passage that _________.

A. the writer thought students shouldn't begin playing the piano too early

B. the writer thought that Robby had given up his piano lessons

C. only by practicing at home did Robby learn to play well

D. no one else could play the piece of Mozart's as well as Robby

3. From the underlined sentence, we can infer that _________.

A. the writer looked down upon Robby and disliked him

B. the writer thought Robby was a bad advertisement for her teaching

C. with Robby in the recital, the other children couldn't play well

D. the writer couldn't teach so many students at a time

4. The writer made Robby perform last because _________.

A. the one who performs last always performs very well

B. Robby asked the writer to do so

C. she wanted to do something to save a poor performance

D. Robby thought his mother would come at last

在起升与运送物件过程中，必须保证起升钢丝绳始终处于垂直状态，严禁物件在空中摇摆。

从2012年秋季学期开始，西藏自治区全面实行了15年免费教育。即凡是在西藏自治区公办学校就读的学生均能享受这一政策，在民办或其他部门办学校就读的学生也可享受等额财政补贴。这一做法（　　）

①加大对少数民族地区投入，不利于实现民族平等

②保障了少数民族的权利，有利于消除民族间的差异

③有利于促进西藏教育发展，实现各民族共同繁荣

④有利于巩固和发展社会主义新型民族关系

A．①②

B．①③

C．②④

D．③④

对空肠弯曲菌感染的治疗首选（）

A.氨基糖苷类

B.喹诺酮类

C.氯霉素

D.红霉素

E.磷霉素