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【单选题】
听力原文：M: Here are our price lists. The quotations are all in US dollars, not FOB. I'm sure you'll find our prices most competitive. W: But these prices are much higher than the ones you quoted half a year ago. M: However, you know that the costs of production have been raised considerably recently. Compared with other computer companies, our prices are still very reasonable. W: I must tell you that your prices are higher than some of the quotations we've received from elsewhere. Would you please quote the most reasonable price? What's the relationship between the man and the woman?A.
Husband and wife
B.
Boss and employee
C.
Teacher and student
D.
Negotiators
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【多选题】能正确检索出“选修'数据库原理与应用'课程的学生学号和姓名”的元组演算表达式：【图片】需要哪些选项同时成立？（ ）
A.
S(u)∧SC(v)∧C(w)
B.
u[1]=v[1] ∧ v[2]=w[1] ∧ t[2]=u[2]
C.
w[2]='数据库原理与应用'
D.
t[1]=u[1]
【单选题】语句printf ( “a\bcd\’ef\’g\\\bij\n”);的输出结果是 _______ 。
A.
a\bcd\’ef\’g\\\bij\n
B.
acd’ef’gbij\n
C.
cd’ef’gij
D.
以上均不正确
【多选题】不能正确检索出“选修'数据库原理与应用'课程的学生学号和姓名”的关系代数表达式是（ ）。
A.
π学号，姓名(σ课程名='数据库原理与应用'(课程∞选课∞学生))
B.
π学号，姓名(σ课程名='数据库原理与应用'(课程∞选课))
C.
π学号，姓名( (π学号 ((σ课程名='数据库原理与应用'(课程))∞选课))∞学生)
D.
π学号，姓名(σ课程名='数据库原理与应用'( 课程∞学生))
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