问题
单项选择题
下述关于数据库系统的叙述中正确的是( )。
A．数据库系统减少了数据冗余
B．数据库系统避免了一切冗余
C．数据库系统中数据的一致性是指数据类型一致
D．数据库系统比文件系统能管理更多的数据
答案
参考答案：B
解析：数据库系统的数据具有高共享性和低冗余性，但不能完全避免数据冗余；数据的一致性是指在系统中同一数据的不同出现应保持相同的值。
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下述关于数据库系统的叙述中正确的是( )。
A．数据库系统减少了数据冗余
B．数据库系统避免了一切冗余
C．数据库系统中数据的一致性是指数据类型一致
D．数据库系统比文件系统能管理更多的数据
参考答案：B
解析：数据库系统的数据具有高共享性和低冗余性，但不能完全避免数据冗余；数据的一致性是指在系统中同一数据的不同出现应保持相同的值。
Heaviest snow in half a century hit the south of the country. It snowed continuously for half a month, ___41__ the railways, highways, and runways in the airfields. Ice wrapped and paralyzed (使瘫痪)the power and communication system. Many people were trapped in railway stations, bus stations and airports, and ___42___ in cars, buses and trains. Governments and people did everything they could ___43___ the snow disaster, no one was killed __ 44___ cold and hunger. Gradually, trapped people all went back home safely. Many moving stories happened during the ___45___. While fighting the snow, people forgot their animal friends until a moving story of a swallow couple was ___46___on the internet. The swallow couple had not eaten anything for several days ___47 _ the snow. They tried to fly into people's home to warm themselves, but every house was closed ___48 _. They got to a side of a balcony (阳台) ___49 _ wind could not reach. They jumped and flapped their wings to attract the attention of the people inside the house, who were busy with their own things. The wife's body was __50__, she could not move any longer. The husband came near and wrapped his wife with his wings. The husband lost his __51__ soon because of his opened wings. The couple died in the cold and hunger, one __52__ another. The next morning, the housemaster went to the balcony to check his flowers and saw a __53__ swallow outside the window pane, touching it, he found that they were two embracing together. Thinking of the __54__ the snow had brought to the people, he was __55__ to tears. He took them in, giving them some warmness which they could not __56__ any longer. He found a small cardboard box, filled it with some hay and __57__ the swallow couple in. He buried them in the back garden. In my hometown in the countryside, a swallow family lives in the roof of my house. They come back from the __58__ every spring to have babies. Then in autumn, when babies have grown up, they fly to the south for __59__. I wonder if they will come back this spring as they __60__. 41．A．protecting B．maintaining C．blocking D．keeping 42．A．even B．still C．yet D．nevertheless 43．A．fight B．fighting C．to fight D．fought 44．A．to B．from C．with D．for 45．A．process B．procedure C．practice D．progress 46．A．common B．widespread C．well-known D．familiar 47．A．regardless of B．instead of C．in addition to D．because of
50．A．frozen B．terrified C．worried D．scared 51．A．faith B．heart C．courage D．heat 52．A．fastening B．packing C．wrapping D．fixing 53．A．dead B．live C．lively D．lovely 54．A．need B．hardship C．poverty D．shortage 55．A．affected B．moved C．encouraged D．satisfied 56．A．find B．gain C．own D．feel 57．A．laid B．lay C．let D．allowed 58．A．west B．east C．south D．north 59．A．spring B．winter C．summer D．autumn 60．A．were B．had C．do D．did |