在关系模型中,关系的“元数”(arity)是指 (22) 。有关系R和S,R∩S的运

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问题:

在关系模型中,关系的“元数”(arity)是指 (22) 。有关系R和S,R∩S的运算等价于 (23) 。设关系R和S的属性个数分别为r和s,则(R×S)操作结果的属性个数为 (24)

A.行数

B.元组个数

C.关系个数

D.列数

考点:计算机软件水平考试初级网络管理员初级网络管理员上午试题
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何谓效果、效率和效益?人类一切活动为何要遵循效益原理?

题型:单项选择题

阅读理解。

     High unemployment is the biggest threat to the global recovery,the head of the International

Monetary Fund (IMF) warned.Dominique StraussKahn,the IMF's managing director,warned

against selfsatisfaction as he pointed out "we are still in a crisis" in spite of the improving

economic conditions.The key to steady growth of economy,he said,would be jobs.

     "A year ago,my worry was a recovery without jobs.This is now certainly a recovery with

not enough jobs,"he said."For_the_young,there_is_now_a_risk_that_will_turn_into_a_life_

sentenee."

     Britain is one of several developed nations facing high levels of joblessness.Total

unemployment is running at 7.8%,but one in five 16 to 24year olds is out of work and the

percentage is still rising,according to the Office for National Statistics.In Italy,youth

unemployment is running at about 30% and at 43% in Spain.The US announced a 27,000

 increase in a weekly unemployment report on Thursday,and unemployment is running at 8.8%.

     Mentioning the disturbing state in the Middle East and North Africa,he added,"Inclusive

growth-sharing the benefits of economic growth fairly,not enough of which is a threat to that

growth,is very important.We have to care about more inclusive growth.We need more than

growth;we need active policies."Mr.StraussKahn said there was "more focus on

unemployment and unfairness" in the IMF.

     Rising food prices also hold back the global recovery,both Mr.StraussKahn and World

Bank President Robert Zoellick warned.Mr.Zoellick said food prices were in the "danger

zone",pushing 44 millon people into poeverty.Rising prices have been driven by the changing

 diet of the rising middle classes in new markets.The problem is being "made worse" by

businessmen and traders.

     He also mentioned some countries' food investment policies.An Asian country has bought

huge areas of fields in Africa to grow enough food to feed its growing middle class.

1.According to the passage,with the recovery of economy,governments should ________.

A.remember the sufferings of the economic crisis

B.be satisfied and pleased with the achievements

C.find methods to deal with high unemployment rates

D.improve working conditions to protect their workers

2.What does the underlined sentence probably mean?

A.More young people will be given a life sentence.

B.There will be more young people breaking the law in the future.

C.The government's law and rules are too long for the young.

D.It will be a long time before there are enough jobs for the young.

3.The author takes Britain,Italy and Spain for example to ________.

A.remind other countries to avoid the same problem

B.show that the unemployment rate of the young is high

C.remind the young to work hard to fight against the crisis

D.encourage other countries to help them go through the crisis

4.Which of the following statements is TRUE?

A.Many countries have bought fields in Africa to grow food.

B.Global recovery is also influenced by rising food prices.

C.Unemployment problems only exist in developing countries.

D.The high unemployment is caused by rising food prices.

5.What does the passage mainly talk about?

A.Joblessness-the biggest threat to the global recovery.

B.The poverty of the developing countries in North Africa.

C.The IMF's determination to take control of food prices.

D.The ways used by the IMF to cut down food prices.

6.用30词左右概括文章大意

__________________________________________________________________________

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先天性卵巢发育不全综合征患儿成年后是否有生育能力取决于()

A.新生儿期即开始治疗

B.使用的雌激素种类

C.染色体核型

D.是否加用人生长激素

E.青春期即开始治疗

题型:单项选择题

某地一位司机在车祸中受重伤,被同行的人送到附近一家医院抢救。经查:伤员多发性骨折,多脏器破裂,如不及时手术,会有生命危险。但手术需要亲属签协议书。可伤员的同行者谁也不敢代签。这时,主刀医师的上级医生签了协议书,表示承担责任。经过医务人员的全力抢救,伤员脱险。

对该上级医生的做法的正确伦理评价应该是()

A.正确,医生在医患关系中居主导地位,最有权力决策

B.正确,权威医生在任何时候都可以代替患者做主

C.正确,医生既已受到患者信托,必要时必须承担责任

D.错误,未经家属委托

E.错误,医生本人和医院承担的风险太大

题型:单项选择题

高压直流系统正常运行方式有:()、()、()。

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