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。

题型:填空题

问题:

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。

考点:计算机等级考试VISUALFOXPRO计算机二级(VF)54
题型:填空题

下列各句中没有语病的一项是(    )

A.卢浮宫、白金汉宫等世界著名宫殿见证了帝国的兴衰和文明的构建,它们以固态的建筑、雕刻、绘画、艺术等诉说着流动的历史和文化。

B.造成高房价的原因主要是土地财政的病灶、腐败枉法的危害、房地产商唯利是图的不良行为和炒房者“搅浑水”的混乱等因素引起的。

C.据郑州市房地产开发协会在房交会上的统计,约有70﹪的被调查者有购房计划,但如何让这些购房需求变成购房行动,是开发商最头疼的问题。

D.事业单位大多数是服务行业,都要制定各自的职业道德和行为规范,促使从业人员养成良好的职业习惯和敬业奉献精神。

题型:填空题

One day while walking along the bank of a river, a rabbit couple(夫妇) saw a wounded(受伤的) ant lying unconsciously(没有直觉地) on the grass. The rabbit couple gently put the ant on the leaf(叶子) of a nearby plant. She soon recovered and saw the rabbit couple sitting beside her.

The ant remembered that she had found herself under the foot of a cat by chance and fainted(晕倒). She asked how she reached the leaf top. The rabbit couple told her what had happened. The ant thanked them and said she would help them when they needed help.

The rabbit couple went further up the river to enjoy the bright sun. They had been there many times and would spend many hours playing and relaxing in the sun.

One fine day, the couple were again on their way to the river while the ant was playing on the leaf of a tree. She saw the rabbit couple walking towards the river. A few hours later she saw the rabbit couple sleeping peacefully on the soft grass by the river. Suddenly she saw a lion moving towards the grass where the rabbit couple were sleeping. The loin saw the rabbit sleeping, and started walking quietly to attack them.

Realizing the hazard getting close to the rabbits, the ant jumped from the leaf to the lion’s shoulder and bit(咬) the lion’s back. The lion cried out in pain, waking the rabbit couple. The rabbits ran away quickly and the ant jumped off the lion’s back into the grass.

A white pigeon(鸽子) who watched this event cheered at the courage(勇气) of the ant and told the whole story to the rabbits. The rabbit couple were moved and thanked the ant. They became best friends.

小题1:From the first three paragraphs, we can learn that _____.

A.the rabbit couple put the ant on the leaf of a plant to hide her

B.the ant was wounded after fighting with a cat

C.the rabbit couple and the ant knew each other very well before

D.the rabbit couple often went to the river小题2:According to the passage, which of the following is TRUE?

A.The ant was hurt by the lion.

B.The ant was small but clever.

C.The white pigeon was as brave as the ant.

D.The lion wanted to play a joke on the rabbit couple.小题3:According to the passage, which is the correct order of the following events?

a.      The ant jumped into the grass to hide.

b.      The ant bit the lion’s back.

c.      The lion moved towards the rabbit couple.

d.      The rabbit couple saved the ant.

e.      The ant saw the rabbit couple sleeping on the grass.

A.d,c,e,a,b

B.d,e,c,b,a

C.e,c,b,a,d

D.c,d,e,b,a小题4:The underlined word “hazard” in the fifth paragraph probably means “_____”.

A.reality

B.warning

C.experience

D.danger

题型:填空题

矿山企业安全管理的主要目的是保护国家矿产资源,使本企业的财产、生产设备免遭损失。

题型:填空题

以下那一项不是政府用于刺激投资的方法()。

A.增加企业信心

B.降低投资成本

C.购买积存的存货

D.增加借贷的可获得性

题型:填空题

肝破裂USG的表现中,哪些描述正确()。

A.肝内血肿-呈无回声区

B.肝内血凝块-呈低回声区

C.肝急性破裂-呈强回声区

D.肝包膜破裂-呈无回声区

E.肝血肿纤维化-呈低回声区

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