/p/, /f/, /s/, /t/, /t∫/,/∫/, /θ/, /r/, /h/, /ts/, and /tr/ are ______.
举一反三
- /p/, /f/, /s/, /t/, /t∫/,/∫/, /θ/, /r/, /h/, /ts/, and /tr/ are ______. A: voiced consonants B: unvoiced consonants
- 设关系R和S的元数分别是r和s,则集合{t|t=t,ts>∧tr∈R∧ts∈S}标记的是()。 A: R∪S B: R-S C: R∩S D: R×S
- 1. 设有关系模式TR(C,P,S,G,T,R),各属性含义分别为:C:课程,P:教师,S:学生,G:成绩,T:时间,R:教室,并存在如下函数依赖集:F={C→G,(S,C)→G,(T,R)→C,(T,P)→R,(T,S)→R},关系模式TR的关键字是________A. (S,C) B. (T,R) C. (T,P) D. (T,S) A: D B: A C: B D: C
- 关系P={C,S,T,R},其函数依赖集:F = {C→T,ST→R,TR→C }。下列哪些是关系模式P的候选码?( )。 A: (C) B: (T,R) C: (S,T) D: (C,S)
- 1 Complete the words. ► h a i r c u t haircut 1 f r _ _ _ e ____ 2 s _ _ s s _ r _ ____ 3 h _ _ r s t _ _ e ____ 4 h _ _ r d _ _ _ r ____ 5 p _ _ t _ n g ____ 6 t _ _ m ____ 7 c _ l _ _ r ____ 8 b l _ w – d r _ ____