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【单选题】
关系代数操作有五种基本的操作，其他操作均可以用这五种基本操作来表达，它们是A.
并、差、交、连接和除
B.
并、差、笛卡儿积、投影和选择
C.
并、交、连接、投影和选择
D.
并、差、交、投影和选择
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举一反三
【单选题】What was the writer ' s ‘ big decision ’?
A.
He decided to write postcards to his friends.
B.
He decided to spend the whole day in his room.
C.
He decided to buy a lot of postcards.
D.
He decided not to write a single card.
【简答题】What was the writer afraid of when he first became a college student?
【简答题】What is the purpose of the letter? 2. Why was the writer sorry? 3. How did Bruce Miles know the matter? 4. What was the writer ready to do to fix the matter?
【简答题】What was the writer interested in seeing on the Climatr Change Walking Tour? Give four details.
【简答题】What was the writer thinking about on the deck after the day ’ s hard work?
【单选题】What was the writer mostly engaged in seventeen years ago?
A.
Passing inspection from the community.
B.
Trying very hard to please the baby girl.
C.
Nurturing the baby girl to become a child.
D.
Running a perfect home to satisfy her husband.
【单选题】What was the writer mostly engaged in seven years ago? 第一段
A.
Passing inspection from the community.
B.
Trying very hard to please the baby girl.
C.
Nurturing the baby girl to become a child.
D.
Running a perfect home to satisfy her husband.
【多选题】根据国网公司优质工程评定办法，对于全站电气照明安装，以下正确的是（）。
A.
灯具基础应高出地面100mm，排列整齐。
B.
灯具应固定牢靠。
C.
金属外壳有明显接地且标识规范清晰。
D.
同列灯具排列整齐划一，高低相同。
相关题目：
【简答题】What was the writer interested in seeing on the Climatr Change Walking Tour? Give four details.