Teachers get upset about instant messaging because ________.
A. children use Internet slang and emoticons in their writing
B. children have trouble with Internet slang and emoticons
C. children cannot tell “it's” from “its”
D. children are sending instant messages in the classroom
查看答案
In an instant message, “G2G”probably means “________.”
A. got too much
B. got to go
C. got two goals
D. got to guess
Which statement is NOT true according to the text?
A. Instant messaging is producing old fears.
B. Children are writing when they send instant messages.
Children's typing skills are improving.
D. Instant messaging is getting in the way of children's lives.
若用如下的SQL语句创建一个Studen表：CREATE TABLE student (NO CHAR(4) NOT NULL，NAME CHAR(8) NOT NULL，SEX CHar (2)，AGE INT (2))可以插入到student表中的是
A. (‘1031’，’曾华’，男，23)
B. (‘1031’，’曾华’，NULL，NULL)
C. (NULL，’曾华’，’男’，’23’)
D. （’1031’，NULL，’男’，23）
为了保护数据库的实体完整性,当用户程序对主码进行更新使主码值不惟一时,DBMS就拒绝此操作
A. 对
B. 错
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