(33)~(34)题的关系代数操作基于如下的关系R和S:把学生的学号及他的平均成绩定

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问题:

(33)~(34)题的关系代数操作基于如下的关系R和S:

把学生的学号及他的平均成绩定义为一个视图。定义这个视图时,所用的.SELECT语句中将出现哪些子句 ( ) Ⅰ.FROM Ⅱ.WHERE Ⅲ.GROUPBY Ⅳ.ORDERBY

A.Ⅰ、Ⅱ

B.Ⅰ、Ⅲ

C.Ⅰ、Ⅱ和Ⅲ

D.全都是

考点:计算机等级考试数据库技术数据库系统基本原理
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甲、乙两车同时从A、B两城出发相向而行.甲每小时行60千米,乙每小时行50千米,出发2小时后乙车行了全程的
3
7
,A、B两城相距多少千米?
题型:单项选择题

介词填空。

1. Since everything develops, we have to make adjustment _____ the changing situation.

2. As a teacher, he is not only strict _____ his students but also strict about his work.

3. I felt worried _________ the result of the final exam.

4. Officials believe that more than one person is to blame     the big fire.

5. The speech by the mayor of Shanghai before the final voting for EXPO 2010 is strongly

     impressed __________ my memory.

6. The sun will rise from your left and pass      your head to set on your right

7. If you want to apply _______ the job, just have a try.

8. Mrs. Smith had much difficulty      preparing a report

9. Even when Marry was dressed up, she didn't look      an elegant (优雅的) lady.

10. We went   ___ a narrow door and got into a room, all damp and cold.

题型:单项选择题

开始起钻前,向井内泵入一段重浆塞,让钻井液液面下降。

井的数据:

钻柱内容积 9.1l/m

钻柱/套管环空容积 26.86l/m

钻井液密度 1.41kg/l

段塞密度 1.96l/m

钻柱中段塞体积 1600升

井深 2805m

当井眼达到平衡后,钻井液液面下降多少?()

A、175.8m.

B、59.6m.

C、68.6m.

D、90.1m.

题型:单项选择题

傣族的村寨大多建于平坝近水的地方,()式建筑是傣族住房的特点,分上、下两层。

题型:单项选择题

以下哪种不是治疗高血压的药物( )。

A.氢氯塞嗪

B.哌唑嗪

C.呱乙啶

D.地高辛

E.卡托普利

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