--- Hi, Terry, can I use your computer for a while this afternoon?
--- Sorry. __ . A. It' s repaired
B. It has been repaired
C. It's being repaired
D. It had been repaired
第1题:
--- Hi, Terry, can I use your computer for a while this afternoon?
--- Sorry. .
A. It' s repaired B. It has been repaired
C. It's being repaired D. It had been repaired
第2题:
下列代码运行时不会产生错误的是?
A.print 'Hi, I'm fine'
B.print "Hi, I'm fine"
C.print 'Hi, I'm fine"
D.print "Hi, I'm fine'
第3题:
10、用氢卤酸分解酚醚时,是HI还是HBr好?为什么?
A.HBr好,因为HBr比HI酸性强,Br-亲核能力I-强。
B.HBr好,因为HBr比HI酸性弱,Br-亲核能力I-弱。
C.HI好,因为HI比HBr酸性强,I-亲核能力比Br-强。
D.HI好,因为HI比HBr酸性弱,I-亲核能力比Br-弱。
第4题:
用氢卤酸分解酚醚时,是HI还是HBr好?为什么?
A.HBr好,因为HBr比HI酸性强,Br-亲核能力I-强。
B.HBr好,因为HBr比HI酸性弱,Br-亲核能力I-弱。
C.HI好,因为HI比HBr酸性强,I-亲核能力比Br-强。
D.HI好,因为HI比HBr酸性弱,I-亲核能力比Br-弱。
第5题:
已知关系R(H,I,J,K,L,M,N),函数依赖集F为{ HI→JM,HK→JL,HN→I,K→J,I→K },问:F的最小覆盖为_________。
A.{ HI→M,HK→J,HN→I,K→J,I→K}
B.{ HI→M,HK→L,HN→I,K→J,I→K}
C.{ HI→J,HI→F,HK→J,HK→L,HN→I,I→K,K→J}
D.{ H→M,I→M,HK→L,H→I,N→I,K→J,I→K}