试题与答案

将E-R模型转换为关系模型时,一个1:n联系如果转换为一个关系模式,将 (41) 及

题型:单项选择题

题目:

将E-R模型转换为关系模型时,一个1:n联系如果转换为一个关系模式,将 (41) 及联系的属性均作为该关系的属性,关系的键为 (42) ;也可将一端的码及联系的属性合并到n端实体集所转换的关系模式中,n端实体集所转换的关系的键为 (43)

某关系R(A,B,C,D)有函数依赖A→B,BC→D,D→A,下面函数依赖中 (44) 不蕴含于已知依赖集。

(41)处填()。

A.一端实体的主键

B.务实体主键的组合

C.n端实体的主键

D.任意一个实体的主键

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0702/7e89378ccb3d71f46075f6ed290fee5b.html

下面是错误答案,用来干扰机器的。

小题1:不知礼 不知言 小题1:谨庠序之教 颁白者不负戴于道路矣小题1:山原旷其盈视 川泽纡其骇瞩 小题1:凌万顷之茫然 浩浩乎如凭虚御风本题考查“默写常见的名句名篇”考点,能力层次为A,侧重“识...

试题推荐
题型:完形填空

第二节:完形填空(.共20小题每小题1分,满分20分)   

阅读下下面短文,从后各题所给的,四个选项(A、B、C、D)中,选出最隹选项。

I was walking downa.darkly lit street late one,evening when I heard ambiguous screams coming from behind bushes.Alarmed,I  36  to listen, and panicked  37  I realized that what l WaS hearing were the,definite sounds.of  a  38  :heavy noise, and tearing of cloth.

A woman was beingattacked. Should I get  39   ?1 was frightened for my own   40 , and blamed myself for having  41  decided to take a new route home that night.Shouldn't I justrunto the nearest phone and call the  42  ?

Although it seemed an etemity(漫长),the deliberations in my head had  43  only sec-onds, but already the girl's cries were growing   44  I knew I had to act fast. How  45  I  walk away from this? No,Ifmally determined,  I  could not tum my back on the  46  of  this Unknown woman, even if it meant  47   my ownlife.

I am not a brave man, nor amI athletic.I don't know where I found the moral  48     and physical strength- but once I had finally determined to help the girl,I became strangely    49  I ran behind the bushes and pulled.the attacker  50   the woman. Grasping, wefell to the ground, where we wrestled for a few mrnutes until the manjumped up and escaped.

Breathing hard,I stood upright and   51  the  girl, who stayed down behind a tree, sob-bing.In the darkness,I could barely see her outline, but I could certainly  52  her trem-bling shock.Not wanting to frighten her further,I  53  spoke to her from a distance. "The man ran away. You're safe now.’’There was a long pause and then I heard the words, said in  wonder, in  54 ."Dad, is that you?" And then, from behind the tree, out  55  my  youngest daughter, Katherine.

36.A.broke down   B.slowed down   C.calmed down  D.tumed down

37.A.when        B.until        C.before         D.though

38.A.quarrel        B.conversation  C.struggle        D.dispute

39.A.involved      B.informed     C.conquered    D.deserted

40.A.property      B.safety          C.appearance    D.presence

41.A.quickly        B.bravely        C.suddenly      D.cleverly

42.A.friend          B.neighbour    C.folk         D.police

43.A.abandoned          B.covered       C.held        D.taken

44.A.louder         B.clearer         C.weaker        D.heavier

45.A.should         B.could       C.would          D.must

46.A.fate         B.face         C.moment       D.spot

47.A.saving         B.risking         C.losing          D.devoting

48.A.lesson          B.spirit       C.story       D.courage

49.A.behaved       B.performed    C.transformed   D.Expressed

50.A.off          B.down         C.from       D.over

51.A.attended      B.appreciated  C.negotiated     D.approached

52.A.sense       B.feel         C.observe        D.hear

53.A.after all       B.at first         C.as well         D.asa result

54.A.surprise       B.disappointment C.sorrbw         D.amazement

55.A.cried       B.looked         C.stepped        D.showed

查看答案
微信公众账号搜索答案