在关系代数中有一种连接操作，要求执行该连接操作的两个关系中进

搜题请搜索小程序“爱下问搜题”

问题单项选择题

在关系代数中有一种连接操作，要求执行该连接操作的两个关系中进行比较的分量必须是相同的属性或属性组，并且在结果中去掉重复的属性。这种连接操作称为（）。

A．半连接

B．等值连接

C．自然连接

D．θ连接

答案

参考答案：C

阅读理解

Read and tick or cross.阅读短文，判断对(√)错(×)。

Uncle Wang has a farm. It's very big. There are many animals on his farm. Look, the horses and

the cows are in the field. They're eating grass. The rabbits are hopping in the field. The ducks are

swimming in the pond (浊塘). Some chickens are on the ground. The pigs are eating some fruits

under the tree. The dog is inside its house.

( )1. The farm is big.

( )2. There are many animals on Uncle Wang's farm

( )3. The pigs are in the river.

( )4. The ducks are swimming.

( )5. The cat is inside its house.

单项选择题 A1/A2型题

男性，45岁。身高168cm，体重83kg，近两个月来，经常于进餐前出现饥饿感，心悸，多汗，进餐后症状缓解，自测空腹血糖6.5mmol／L，为明确诊断。该患最合适的检查为（）。

A.甲状腺功能监测

B.胰腺CT

C.心电图

D.尿常规

E.OGTT