若D1=a1,a2,a3),D2=b1,b2,b3,则D1×D2集合中共有元组___

题型:填空题

问题:

若D1=a1,a2,a3),D2=b1,b2,b3,则D1×D2集合中共有元组______个。

考点:计算机等级考试数据库技术三级数据库技术笔试
题型:填空题
In California, there lives a pretty girl called Donna Green. She is   26__  18-year-old girl with big eyes and golden hair. She is good at singing and  27_  the first place in the Singing Competition three times.
However, She became very weak two years ago. She had an unhealthy heart. “Donna needs a new heart,   28  she will die soon,” the doctor said.
Jim Smith,   29  was worried about Donna, was her best friend. He liked her very much and didn’t want her   30 . Jim talked to his mother about Donna. “If I am going to die, I   31  my heart to Donna.” Jim’s mother didn’t pay much attention to him. She thought, “Jim is strong and healthy. He is still young.”
But Jim was not healthy at all. He   32  had terrible headaches. One morning, he woke up   33  a sharp pain in his head and   34  breathe. The Smiths rushed Jim to the hospital, but the doctor couldn’t save him. The Smiths were heart-broken. Yet they remembered Jim’s words. Jim wanted to give his heart to Donna!
After several tests, Jim’s heart   35  out and put into Donna’s chest. In a short time, the heart began to beat. The operation was a success.
Now, Donna can sing again. She is thankful to Jim for the great gift.
小题1:  
A.aB.anC.theD./
小题2:
A.winsB.wonC.has wonD.had won
小题3:
A.orB.andC.butD.so
小题4:
A.whomB.whoC.whichD.that
小题5:
A.dieB.to dieC.dyingD.died
小题6:  
A.give B.have givenC.would giveD.will gave
小题7:  
A.some timeB.some timesC.sometimeD.sometimes
小题8:  
A.in B.withC.of D.on
小题9:  
A.couldn’tB.mustn’tC.might notD.shouldn’t
小题10: 
A.tookB.is takenC.was takenD.has taken
题型:填空题

如图所示是用电流传感器(相当于电流表,其电阻可以忽略不计)研究自感现象的实验电路,图中两个电阻的阻值均为R,L是一个自感系数足够大的自感线圈,其直流电阻值也为R,下图是某同学画出的在t0时刻开关S切换前后,通过传感器的电流随时间变化的图象,关于这些图象,下列说法中正确的是

[ ]

A.甲图是开关S由断开变为闭合,通过传感器1的电流随时间变化的情况

B.乙图是开关S由断开变为闭合,通过传感器1的电流随时间变化的情况

C.丙图是开关S由闭合变为断开,通过传感器2的电流随时间变化的情况

D.丁图是开关S由闭合变为断开,通过传感器2的电流随时间变化的情况

题型:填空题

腔隙性脑梗死

A.是发生卒中的先兆
B.可能发展为严重的偏瘫
C.可能发展为失语症
D.可能发展为共济失调
E.一般不损伤高级皮质功能

题型:填空题

一等奖学金:学期综合素质考评总分排名介于本班级()

A.5-15%

B.10-15%

C.15-20%

D.20-30%

题型:填空题

储运商品的化学变化有()。

A.化合与分解

B.水解

C.氧化

D.锈蚀

E.老化

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