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问题 单项选择题

在三级模式之间引入两级映像，其主要功能之一是( )。

A．使数据与程序具有较高的独立性

B．使系统具有较高的通道能力

C．保持数据与程序的一致性

D．提高存储空间的利用率

答案

参考答案：A

改错题
短文改错。
     此题要求在答题卡上改正所给短文中的错误，对标有题号的每一行作出判断：
如有错误（每行只有一个错误），则按下列情况改正：
此行多一个词：把多余的词用斜线（\）划掉，在该行右边横线上写出该词，并用斜线划掉。
此行缺一个词，在缺词处加一个漏字符号（∧），在该行右边横线上写出该加的单词。
此行错一个词，在错词下划一道线，在该行右边横线上写出改正后的单词。
注意：原行没有错误的不要改。
     Are the years you spent at school best years of you life?         
Personally, I found most lesson rather uninteresting. We had to   
sit at our desks in silence and paid attention to what the teachers 
were saying. They were used to write on the blackboard and ask   
us difficult questions. We also had to do plenty of homework, so  
hand it on time. We had to wear school uniforms and obey lots of 
 rules. I left school as soon as I can and started work. I read books
at the public library, and late I decided to attend college. Now  
I really enjoy study because I’m growing old and know what I      
want it. When I was at school. I was just the wrong age!          		1______
2______
3______
4______
5______
6______                          
7______
8______
9______
10______
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单项选择题

在钢结构中，通常用来做钢筋、型钢和钢板的碳素结构钢是（）。

A．Q215

B．Q235

C．Q255

D．Q275
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