在数据库的三级组织结构中存在着两种映射:一是 【10】 之间的映射,二是模式与子模式

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问题:

在数据库的三级组织结构中存在着两种映射:一是 【10】 之间的映射,二是模式与子模式之间的映射。

考点:计算机等级考试数据库技术三级数据库技术笔试
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新华网石家庄 2008年9月2日 电,3年前崔彤的爸爸突遭车祸,成为医学上的植物人。但在1 2岁的女儿孝心滋润下,三个多月的病榻之痛竟然创造了一个生命的奇迹。随后,从孝心到爱心,这一奇迹被传播,直至倾城……崔彤的故事感动了廊坊,廊坊也报以倾城之爱滋润着这个阳光女孩。于是,崔彤以及崔彤背后的爱心故事一直延续到今天。  

根据材料说明,建设和谐文化我们公民应该  

① 在全社会形成互爱互助的良好社会风尚   

② 调动广大人民群众参与其中,用爱心感动他人  

③ 让中 * * 优良的传统美德发扬光大  

④ 加强社会主义核心价值体系建设  

A.①②③

B.②③④

C.①②④

D.①②③④

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高压配电网架应与二次送电网密切配合,且比后者有更强的适应性,一般采用()等结线方式。

A.放射式

B.格网式

C.环式

D.多回线式

E.联络线

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据专家测算,3个关不紧的水龙头一个月能浪费掉18吨水,某单位有5个关不紧的水龙头,如果不及时修理,一个月能浪费掉多少吨水?一年呢?(用比例方法解)

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治疗劳作过度引起肩周疼痛,疼痛拒按,舌暗,脉涩,除肩部穴外,还应选取( )

A.后溪、申脉
B.三阴交、气海
C.外关、风池
D.内关、膈俞
E.合谷、风池

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Questions 6~10


It is Monday morning, and you are having trouble waking your teenagers. You are not alone. Indeed, each morning, few of the country’s 17 million high school students are awake enough to get much out of their first class, particularly if it starts before 8 am. Sure, many of them stayed up too late the night before, but not because they wanted to.
Research shows that teenagers’ body clocks are set to as schedule that is different from that of younger children or adults. This prevents adolescents from dropping off until around 11 pm, when they produce the sleep-inducing hormone melatonin, and waking up much before 8 am when their bodies stop producing melatonin.
The result is that the first class of the morning is often a waste, with as many as 28 percent of students falling asleep; according to a National Sleep foundation poll. Some are so sleepy they do not even show up, contributing to failure and dropout rates.
Here is an idea: stop focusing on testing and instead support changing the hours of the school day, starting it later for teenagers and ending it later for all children. Indeed, no one does well when they are sleep-deprived, but insufficient sleep among children has been linked to obesity and to learning issues like attention deficit/hyperactivity disorder. You would think this would spur educators to take action, and a few have.
In 2002, high schools in Jessamine County in Kentucky pushed back the first bell to 8:40 am, from 7:30 am. Attendance immediately went up, as did scores on standardized tests, which have continued to rise each year. In Minneapolis and Edina, Minnesota, which instituted high school start times of 8:40 am and 8:30 am respectively in 1997, students’ grades rose slightly and lateness, behavioral problems and dropout rates decreases. Later is also safer. When high schools in Fayette County in Kentucky delayed their start times to 8:30 am, the number of teenagers involved in car crashes dropped, even as they rose in the state.
So why has not every school board moved back that first bell Well, it seems that improving teenagers’ performance takes a back seat to more pressing concerns: the cost of additional bus service, the difficulty of adjusting after school activity schedules and the inconvenience to teachers and parents.
But few of these problems actually come to pass, according to the Center for Applied Research and Educational Improvement at the University of Minnesota. In Kentucky and Minnesota, simply flipping the starting times for the elementary and high schools meant no extra cost for buses.
There are other reasons to start and end school at a later time. According to Paul Reville, a professor of education policy at Harvard and chairman of the Massachusetts Board of Education, "trying to cram everything out 21th-century students need into a 19th-century six-and-a-half-hour day just isn’t working". He said that children learn more at a less frantic pace, and that lengthening the school day would help "close the achievement gap between disadvantaged students and their better-off peers".

According to the passage, what determines a person’s body clock is ______.

A. melatonin production
B. one’s lifestyle
C. schedule setting
D. one’s sleep patterns

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