在关系模型中，“关系中不允许出现相同元组”的约束是通过【 】实现的。

抽出物为不凝固血液（）

A．腹内实质性脏器损伤

B．肠道损伤

C．胃破裂

D．胆囊破裂

E．膀胱破裂 根据下列伤后腹腔穿刺情况，可以初诊为哪种损伤

某房地产企业计划一季度在本公司A、B、C三个地区市场按4000元／m²、5000元／m²、6000元／m²、的价格销售商品房2000m²、2500m²、3000m²、但季末检查的情况是A地区以3900元／m²、的价格售出2300m²、，B地区以460元／m²、的价格售出2200m²、，C地区以6000元／m²、的价格售出3300m²、。

通过分析，可以得出以下结论（）。

A.企业在A地区的竞争地位上升

B.企业在C地区竞争地位上升得更快

C.企业在B地区销售不理想的原因可能是原来的目标定得不妥

D.难以比较企业在各地区市场上的竞争地位

阅读理解

     ALMOST everyone wants to get smarter. We struggle to improve our memory, intelligence, and

attention span. We drink cup after cup of coffee to help us get through the day.

     However, a new study published in the journal Current Directions in Psychological Science warns that

there are limits to how smart humans can get, and trying to increase your thinking ability could be urisky.

     Each of our body parts evolved in a certain way for a reason. For example, we are not 3 meters tall

because most people's hearts are not strong enough to send blood up that high. Scientists are now saying

that our thinking ability works in the same way. A baby's brain size is limited by a series of factors, such as the size of the mother's pelvis (骨盆). If our brains evolved to vbe bigger, there could be more deaths

during childbirth.

     The study of Ashkenazi Jews (德裔犹太人), who have an average IQ much higher than other

Europeans, showed that they were more likely to develop diseases of the nervous system. This might be

because of their increased brainpower.

     If intelligence cannot be improved, can we at least get better at concentrating? Not really, say scientists. They studied drugs like caffeine that improve attention span. They found that the drugs only helped people with serious attention problems. For those who did not have trouble paying attention, the drugs could have the opposite effect. Scientists say that this suggests there is an upper limit to how much people can or

should concentrate.

     Our memory is also a "double-edged sword (双刃剑)". People with extremely vivid (生动的)

memories could end up having a difficult life because they cannot forget bad things that happen to them.

Thomas Hills of the University of Warwick in the UK, one of the authors of the paper, said that

considering all the problems in trying to get smarter, it's unlikely there will ever be a "supermind".

1. Which of the following aspects do the scientists refer to in order to explain that there will never be a

"supermind"?

  a. intelligence   b. nervous system    c. concentration ability  d. memory  e. heart disease

A. abc        

B. acd          

C. bcd              

D. cde

2. Our heights and babies' brain size are mentioned to prove that ______.

A. there are limits to people's intelligence

B. a baby's IQ is determined by the mother's pelvis

C. most people's hearts are not that strong to make them smarter

D. it's likely that people's body parts will continue to evolve

3. Which of the following is TRUE on concentration in the fifth paragraph?

A. There is no case where concentration is improved.

B. Coffee does help a little in some people's concentration.

C. The drugs work for those who do not have attention trouble.

D. With the help of the drugs, we can gain better concentration.

4. What does the author mean by saying "Our memory is also a 'double-edged sword '"?

A. Good memory can lead to bad results, too.

B. Good memory will lead to diseases in people's body.

C. Without memory, people will lead a better life.

D. Poor memory makes people more generous.

抗日战争时期，中国沿海地区和一些抗战前沿省份的部分厂矿进行了大规模内迁，人们称之为“中国实业界的敦克尔刻”。它

①改变了近代中国的工业布局②促进了民族工业的迅速发展

③奠定了抗战胜利的物质基础④引起了近代中国工业结构的变化[ ]

A．①③④

B．①②③

C．②③④

D．①②③④

数字录像设备的故障监测包括：（）

A、录像状态

B、硬盘空间占用

C、视频丢失

D、硬盘故障

E、进程异常

F、心跳超时