【判断题】全局阈值法中的基本全局阈值方法较最佳全局阈值法适用范围更大。
【单选题】Everybody must have _____own choice.
【简答题】A.пsname(S)D∞ σPno='P3'(SPJ) B.пsname(SD∞ σPno='P3'(SPJ)) C.пsname(S)-пsname(σPno≠'P3'(S∞(SPJ) D.пsname(S)-пsname((S∞σPno≠'P3',(SPJ)
【单选题】现有学生关系表S(sno,sname,ssex,sage),下列选项中 与关系代数表达式 Π sno,sname (S) 等价的 SQL 语句是 ________ 。
A.
select * from S where sno, sname;
B.
select from S where sno, sname;
C.
select sno, sname from S where *;
D.
select sno, sname from S;
【简答题】A.Πsname(S)-Πsname(σPno≠'P3'(S∞(SPJ) B.Πsname(S)—nsname((S∞σPno≠'P3'(SPJ) C.Πsname(S)D∞σPno='P3'(SPJ) D.Πsname(SD∞σPno='P3'(SPJ))
【单选题】当两个风险资产所构成的资产组合可行集是两条直线,相交于Y轴(风险为零)时,相关系数应为多少
【单选题】Everybody must have ___ own choice.
【判断题】全局阈值法中的基本全局阈值方法较最佳全局阈值法适用范围更大。
【单选题】听力原文:W: You must have forgotten the meeting. I didn't see you last night. M: Everybody says that to me and they think I have a bad memory. In fact I would have come to the meeting if I had known about...
A.
He has forgotten the meeting.
C.
He didn't get the message about the meeting.
D.
He didn't want to attend the meeting.
【单选题】.Everybody must have ___ own choice.