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问题 填空题

在关系数据库中，用来表示实体之间联系的是 【4】 。

答案

参考答案：二维表

解析： 在关系模型中，实体以及实体间的联系都是用关系表示的。关系模型中数据的逻辑结构；一张二维表。

改错题

第二节：短文改错(满分10分)

下面短文中有10处语言错误。请在有错误的地方增加、删除或修改某个单词。

增加：在缺词处加一个漏词符号(∧)，并在其下面写上该加的词。

删除：把多余的词用斜线(＼)划掉。

修改：在错的词下划一横线，并在该词下面写上修改后的词。

注意：1.每处错误及其修改均仅限一词；

2.只允许修改10处，多者（从第11处起）不给分。

I live in a very old town which is surrounding by beautiful woods. It is a famous beauty spot. In Sundays, hundreds of people come from the city to see our town and to walk through the woods. Visitors have asked to keep the woods clean and tidy. Litter baskets have been placed under the trees, and people still throw their rubbish everywhere. Last Wednesday, I go for a walk in the woods. That I saw made me very sad. I counted seven old cars and three old refrigerators. The litter basket were empty and the ground was covered with pieces of paper, cigarette ends, old tyres, empty bottles or rusty tins. Among the rubbish, I found a sign which was said, “Anyone who leave litter in these woods will be prosecuted(依法处置)!”
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单项选择题

系统试压时先缓慢将压力升到试验压力的（）%，全面检查无泄漏，再将压力升至试验压力的（）%，检查无异常，每级按试验压力的（）%逐级升至试验压力，保压10-30分钟，全面检查无问题，试压合格。

A、10、30、20

B、10、50、20

C、30、50、10

D、10、50、10
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