问题 单项选择题

数据仓库的内容是随时间变化的,这种变化趋势不包括______。

A.不断增加新的数据内容

B.捕捉到的新数据会覆盖旧的快照

C.不断删去过期的数据内容

D.综合数据将随时间变化而不断地进行重新综合

答案

参考答案:C

解析:[分析] 数据仓库是决策支持系统(dss)和联机分析应用数据源的结构化数据环境。数据仓库研究和解决从数据库中获取信息的问题。数据仓库的特征在于面向主题、集成性、稳定性和时变性。数据仓库是不可更新的,数据仓库主要是为决策分析提供数据,所涉及的操作主要是数据的查询;数据仓库是随时间而变化的,传统的关系数据库系统比较适合处理格式化的数据,能够较好地满足商业商务处理的需求。稳定的数据以只读格式保存,且不随时间改变。

单项选择题

A

“Did you hear what happened to Adam Last Friday?”Lindsey whipers to Tori.

With her eyes shining,tori brags,“You bet I did,Sean told me two days ago.”

Who are Lindsey and Tori talking about?It just happened to be yours truly,Adam Freedmam,I can tell you that what that what they are saying is (a) not nice and (b) not even true.Still,Lindsey and Tori aren’t very different from most students here at Linton Higt School,including me.Many of our conversations are gossip(闲话)。I have noticed three effects of gossip:it can hurt people,it can give gossipers a strange kind of satisfaction,and it can cause social pressures in a group.

An important negative effect of gossip is that it can hurt the person being talked about.Usually,gossip spreads information about a topic-breakups,trouble at home,even dropping out-that a person would rather keep secret.The more embarrassing or shameful the secret is,the juicier the gossip it makes.Probably the worst type of gossip is the absolute lie.People ofen think of gossipers as harmless,but cruel lies can cause pain.

If we know that gossip can be harmful,then why do so many of us do it?Tht answer lies in another effect of gossip:the satisfaction it gives us.Sharing the latest rumor(传言)can make a person feel important because he or she knows something that others don’t.Similarly,hearing the latest rumor can make a person feel like part of the “in group.”In other words,gossip is satisfying because it gives people a sense of belonging or even superiority(优越感).

Gossip also can have a third effect:it strengthens unwritten,unspoken rules about how people should act.Professor David Wilson explains that gossip is important in policing behaviors in a group.Translated into high school terms, this means that if everybody you hang around with is laughing at what John wore or what Jane said,then you can bet that wearing or saying something similar will get you the same kind of negative attention.The do’s and don’ts conveyed through gossip will never show up in any student handbook.

The effects of gossip vary depending on the situation.The next time you feel the urge to spread the latest news,thing about why you want to gossip and what effects your “juicy story”might have.

What advice does the author give in the passage?()

A.Never become a gossiper

B.Stay away from gossipers

C.Don’t let gossip turn into lies

D.Think twice before you gossip

判断题