设计性能较优的关系模式称为规范化,规范化主要的理论依据是()。
A.关系规范化理论
B.关系运算理论
C.关系代数理论
D.数理逻辑
参考答案:A
解析:这种循环等待的现象称为死锁。
初中生小雅的父母以家庭困难为由,让其辍学到工厂上班以减轻家庭经济负担。小雅的父母的行为侵犯了她的( )
A.人身自由权
B.受教育权
C.人格尊严权
D.社会经济权利
— Do you know where David is? I couldn't find him anywhere.
— Well. He _____ have gone far-his coat is still here. [ ]
A. shouldn't
B. mustn't
C. can't
D. wouldn't