关于关系演算语言，下列说法中正确的是（）。①查询操作是以集合操作为基础运算的DML②查询操作是以谓词演算为基础运算的DML③关系演算语言的基础是数理逻辑中的谓词演算④关系演算语言是一种过程性语言

>> 成人高等教育 / 数据库原理与应用

成人高等教育 / 数据库原理与应用

A、
②
B、
②③
C、
②③④
D、
全部

积分

数据库原理与应用

参考答案：

点击查看答案

佳题速递：

3[名词解释题] 逻辑普通逻辑学

题型描述: 阅读理解Community service is an important component of education here at our university. We encourage all students to volunteer for at least one community activity before they graduate. A new community program called "One On One" helps elementary students whoˊve fallen be?hind. Your education majors might be especially interested in it because it offers the opportu?nity to do some teaching, that is, tutoring in math and English.Youˊd have to volunteer two hours a week for one semester. You can choose to help a child with math, English, or both. Half-hour lessons are fine, so you could do a half hour of each subject two days a week.Professor Dodge will act as a mentor to the tutors—heˊll be available to help you with lesson plans or to offer suggestions for activities. He has office hours every Tuesday and Thursday afternoon. You can sign up for the program with him and begin the tutoring next week.Iˊm sure youˊll enjoy this community service…and youˊll gain valuable experience at the same time. It looks good on your resume, too, showing that youˊve had experience with children and that you care about your community. If youˊd like to sign up, or if you have any questions, stop by Professor Dodgeˊs office this week.1、 What is the purpose of the talk? A. To recruit elementary school teachers for a special program. B. To interest students in a new community program. C. To explain a new requirement for graduation. D. To discuss the problems of elementary school students. 2、 What is the purpose of the program that the speaker describes? A. To help education majors prepare for final exams. B. To offer tutorials to elementary school students. C. To find jobs for graduating students. D. To provide funding for a community service project. 3、 What does Professor Dodge do? A. He advises students to participate in certain program. B. He observes elementary school students in the classroom. C. He helps students prepare their resumes. D. He teaches part-time in an elementary school. 4、 What should students who are interested in the tutorials do? A. Submit a resume to the dean. B. Sign up for a special class. C. Talk to Professor Dodge. D. Contact the elementary school. 5、 Whom do you think the speaker addresses? A. Graduated students. B. Residents. C. Students. D. Faculty.统考英语B

8．商统治者立法的指导思想，仍沿袭了夏朝的神权思想。 A、正确 B、错误中国法制史

房地产投资的优点不包括_________。个性差异小，易操作可运用财务杠杆具有分散投资的效应能抵御通胀个人理财

143、八进制数执行______的运算法则。 A.逢八进一 B.逢二进一 C.逢十进一 D.逢十六进一计算机统考

[论述题] 简述树立正确的游戏教育观中学语文教学法