题目内容

8.想要删除数据库中已经存在的数据表,可以使用()语句。

A.CREATE TABLE
B.DROP DATABASE
C.ALERT TABLE
D.DROP TABLE

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9.下列关于索引的描述中,错误的是()。

A.主键是一种特殊唯一索引。
B.MySQL中只有MyISAM存储引擎支持空间检索。
C.使用SPATIAL参数可以设置唯一索引。
D.文索引只能创建在CHAR、VARCHAR或者TEXT类型的字段上。

10.在MySQL中,非空约束可以通过()关键字定义。

A.NOT NULL
B.DEFAULT
C.CHECK
D.UNIQUE

When you talk with new friends, usually there are1 in the conversation. The first par is greeting. In this part, you and your new friend will greet each other and tell each other your names or 2 name cards.The second part is the conversation itself. So sometimes the conversation is just 3 . That is, you talk about unimportant matters, such as the weather, sports, entertainments and other interesting things. But it’s not the time for you to ask about 4 or unpleasant thing. Sometimes the conversation is about important matters like 5 . The third part of the conversation is the leave taking part. In this part, you tell your new friend that you’re happy to have met him or her and then the conversation comes to the end.

1.What do many young people think of the Internet?It is a good place to.2.What can young people practice on the Internet?They can practice by talking with people.3.What is important for young people to know when talking with strangers online?Talking with strangers online can be .4.What should you do to protect yourself online?Never give yourto anyone.5.What should you do if you feel uncomfortable with the topics of conversation?Stop.