【简答题】设有如下关系表: 则下列操作正确的是( )。 A)T=R/S B)T=R∩S C)T=R×S D)T=R∪S
【简答题】Peter: Let’s play computer s! Barry: That sounds interesting, but I don't have a computer. Peter: Well, do you have a volleyball? Barry: Yes. Peter: Then let's play volleyball. Barry: Oh, volleyba...
【简答题】根据对话情景,填入恰当的单词。(每空一词,每词1分,共6分) M: Hi, Barry. So what’s the plan? W: Do you feel like playing tennis tonight? M: That’s a good idea. I haven’t played tennis in ages. W: Great. Is 7:00 all right? M: Cou...
【单选题】Who's 'Buddy'?
D.
George Washington's play-date.
【简答题】设有如下三个关系表 下列操作中正确的是 A)T=R ∩ S B)T=R ∪ S C)T=R × S D)T=R/S
【简答题】(33)设关系 R 和S 的元数分别是r 和 s,则集合{t | t = S }标记的是 A)R ? S B)R—S C)R ? S D)R ? S
【简答题】Thanks to the Web, We’re Alone Together and Loving it There's a professor, Barry Wellman, at the University of Toronto in Canada who has come up with a term to describe the way a lot of us North Ameri...