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【单选题】
数据库表中主键约束和唯一性约束的区别在于()
A.
一个表只能定义一个主键约束，主键值可以为空
B.
一个表可以定义多个主键约束，主键值可以为空
C.
一个表只能定义一个主键约束，主键值不能为空
D.
一个表可以定义多个主键约束，主键值不能为空
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参考答案：
举一反三
【单选题】评定参数( )更能充分反应被测表面的实际情况。
A.
绝轮廓的最大高度
B.
绝微观不平度十点高度
C.
绝轮廓算术平均偏差
D.
绝轮廓的支承长度率
查看完整题目与答案
【简答题】用适当的词填空。 1. The sound and video are not _______ good as TV. 2. We can get news _______ many ways. 3. Many people like the news ________ TV. 4. The news is on TV only ________ certain times. 5. most TV...
查看完整题目与答案
【简答题】There are different 1)of media today. News and 2)are communicated to us in a number of different ways, using different media. It may be 3) media such as newspapers and magazines, or 4)media such as ra...
查看完整题目与答案
【判断题】Φ60H7铰孔前的扩孔尺寸应该为Φ8左右。
A.
正确
B.
错误
查看完整题目与答案
【简答题】补全对话。根据对话内容，在空格中填写一个句子，使对话完整、正确。（共5小题，每题2分） (On Saturday.   Li Lei – L    Han Jie – H) L: 小题1:___________________________ ? H:  I watched TV at home last night. L: 小题2:________________________________...
查看完整题目与答案
【简答题】There are many kinds of entertainment for children today－books, movies, s and sports are only a few of possibilities. Television is one of the most influential kinds of __1__. Studies show that el...
查看完整题目与答案
【简答题】听下面一段材料。回答第1-2题。 1. Why does Greener World develop educational programs for schools? A. To show children how the oceans are being polluted. B. To tell children why over-fishing can happen. C. To make ...
查看完整题目与答案
【简答题】DIY, which means Do It Yourself, is quite popular in the UK. Lots of stores and supermarkets sell DIY things. TV programs show people how to DIY. English people like DIY. If there is anything that nee...
查看完整题目与答案
【单选题】评定参数（ ）更能充分反应被测表面的实际情况。
A.
Ra
B.
Rz
C.
Rmr（c）
D.
RSm
查看完整题目与答案
【多选题】Show programs are various, such as drama, magic, and in the stage with extravagant sets and scenery.
A.
music play
B.
singing
C.
dancing
D.
acrobatic
查看完整题目与答案
相关题目：
【单选题】评定参数( )更能充分反应被测表面的实际情况。
A.
绝轮廓的最大高度
B.
绝微观不平度十点高度
C.
绝轮廓算术平均偏差
D.
绝轮廓的支承长度率
查看完整题目与答案
【简答题】用适当的词填空。 1. The sound and video are not _______ good as TV. 2. We can get news _______ many ways. 3. Many people like the news ________ TV. 4. The news is on TV only ________ certain times. 5. most TV...
查看完整题目与答案
【简答题】There are different 1)of media today. News and 2)are communicated to us in a number of different ways, using different media. It may be 3) media such as newspapers and magazines, or 4)media such as ra...
查看完整题目与答案
【判断题】Φ60H7铰孔前的扩孔尺寸应该为Φ8左右。
A.
正确
B.
错误
查看完整题目与答案
【简答题】补全对话。根据对话内容，在空格中填写一个句子，使对话完整、正确。（共5小题，每题2分） (On Saturday.   Li Lei – L    Han Jie – H) L: 小题1:___________________________ ? H:  I watched TV at home last night. L: 小题2:________________________________...
查看完整题目与答案
【简答题】There are many kinds of entertainment for children today－books, movies, s and sports are only a few of possibilities. Television is one of the most influential kinds of __1__. Studies show that el...
查看完整题目与答案
【简答题】听下面一段材料。回答第1-2题。 1. Why does Greener World develop educational programs for schools? A. To show children how the oceans are being polluted. B. To tell children why over-fishing can happen. C. To make ...
查看完整题目与答案
【简答题】DIY, which means Do It Yourself, is quite popular in the UK. Lots of stores and supermarkets sell DIY things. TV programs show people how to DIY. English people like DIY. If there is anything that nee...
查看完整题目与答案
【单选题】评定参数（ ）更能充分反应被测表面的实际情况。
A.
Ra
B.
Rz
C.
Rmr（c）
D.
RSm
查看完整题目与答案
【多选题】Show programs are various, such as drama, magic, and in the stage with extravagant sets and scenery.
A.
music play
B.
singing
C.
dancing
D.
acrobatic
查看完整题目与答案
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