数据库物理设计的目标是为应用数据提供合适的数据存储结构,同时要保证数据库系统具有良好的性能。关于数据库物理设计,下列说法中错误的是( )。
A. 数据库物理设计需要考虑数据的存储方式、存取路径和具体的实现细节,还需要考虑数据的加载方式
B. 数据库物理设计一般需要根据数据的存储需求和使用需求确定数据库管理系统的配置参数
C. 数据库物理设计需要权衡系统的时间效率、空问效率、维护代价和各种用户要求,因此可能会产生多个备选方案
D. 在数据库物理设计后期,可以根据实际需要适当降低某些关系模式的规范化程度,以提高查询效率
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下列关于Windows 2003系统DHCP服务器的描述中,错误的是( )。
A. DHCP服务器负责多个网段IP地址分配时,需要配置多个作用域
B. 客户机与DHCP服务器不在一个网段时,需DHCP中继转发DHCP消息
C. DHCP中继转发DHCP发现消息时,需修改该消息中的相关字段
DHCP中继转发客户机的消息时,仍使用广播方式发送给DHCP服务器
To absorb a younger work force, many companies offered retirement plans as incentives for older workers to retire and make way for the younger ones who earned lower salaries.
A. rewards
B. opportunities
C. motives
D. stimulus
阅读材料,回答题。 Deport them or notIn a country that defines itself by ideals,not by shared blood,who should be allowed to come,work and live here?In the wake of the Sept.1 1 attacks these questions have never seemed more pressing.On Dec.11,2001,as part of the effort to increase homeland security,federal and local authorities in 14 states staged“Operation Safe Travel”-raids on airports to arrest employees with false identification(身份证明).In Salt Lake City there were 69 arrests.But those captured were anything but terrorists,most of themillegal immigrants from Central or South America.Authorities said the undocumented workers’illegal status made them open to blackmail(讹诈)by terrorists.Many immigrants in Salt Lake City were angered by the arrests and said they felt as if they were being treated like disposable goods.Mayor Anderson said those feelings were justified to a certain extent,“We’re saying we want you to work in these places,we’re going to look the other way in terms of what our laws are,and then when it’s convenient for us,or when we can try to make a point in terms of national security,especially after Sept.1 1,then you’re disposable.There are whole families being uprooted for all of the wrong reasons,”Anderson said.If Sept.1 1 had never happened.the airport workers would not have been arrested and could have gone oil quietly living in America.probably indefinitely.Ana Castr0,a manager at a Ben&Jerry’s ice cream shop at the airport,had been workin9 10 years with the same false Social Security card when she was arrested in the December airport raid.Now she and her family are living under the threat of deportation(驱逐出境).Castro’s case is currently waiting to be settled.While she awaits the outcome,the government has granted her permission to work here and she has returned to her job at Ben&Jerry’s.According to the author,the United States claims to be a nation__________.
A. composed of people having different values
B. encouraging individual pursuits
C. sharing common interests
D. founded on shared ideals
(题共用题干)患者,男性,68岁,风湿性心脏瓣膜病,二尖辫狭窄10余年。3天前受凉后出现咳嗽,咯黄色黏痰,伴发热,体温最高为38.3℃,伴胸闷、心悸气短,上5层楼梯需中间休息5分钟,自服感冒药后未见改善,急诊以“风湿性心脏瓣膜病、心衰、肺部感染”收入院。引起该患者发生心衰的基本病因是
A. 原发性的心肌损害
B. 继发性心肌代谢障碍
C. 心室后负荷过重
D. 心室舒张充盈受限
E. 心室前负荷过重