Yan'an was called Yanzhou in ancient times, and the name Yan'an began from Yan'an County which was established in the third year of the Sui Dynasty (in 607 AD), and it has been more than 1400 years.( ).

Yan'an was called Yanzhou in ancient times, and the name "Yan'an" began from Yan'an County which was established in the third year of the Sui Dynasty (in 607 AD), and it has been more than 1400 years.（ ）。

已知关系R(A,B,C,D,E,F,G),函数依赖集F为{AB→CF,AD→CE,AG→B,D→C,B→D},F的最小函数依赖集为_________。 A: {AB→C,AB→F,AD→C,AD→E,AG→B,B→D,D→C} B: {AB→F,AD→E,AG→B,D→C,B→D} C: {AB→F,AD→C,AG→B,D→C,B→D} D: {A→F,B→F,AD→E,A→B,G→B,D→C,B→D}

F=A/B BD CDE /AD=( )。

逻辑函数F=AB'CD+ABC'D'+AB'+AD'+AB'C化简为 A: AB’+AD’ B: AB+CD C: A+B D: BC+D

己知逻辑表达式 F=A'C+AD+D'C，下列（ ）与F功能相同。 A: F=AD B: F=AD+C C: F=AD+A'C D: F= AD+D'C

Photoshop常用的文件格式有() A: psd B: jpg C: png D: gⅰf

已知关系模式R(A,B,C,D,E,F),其函数依赖集F={A→BC,B→C,CD→EF},则下列函数依赖不成立的是()。 A: A→B B: AD→F C: BC→CD D: AD→CD

在关系模式R(U，F)中，U=ABCDE，F={AB→C，BC→D，AD→E}。则R 的码是 A: AB B: BC C: AD D: 以上三者都不是

最早应用的无线电导航设备是（）。 A: AD B: F C: VOR D: DM E: E F: ILS