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关系R1和R2如下图所示：

若进行R1∞R2运算，则结果集分别为（）元关系，共有（）个元组。

已知关系模式：图书（图书编号，图书类型，图书名称，作者，出版社，出版日期，ISBN），图书编号唯一识别一本图书。建立“计算机”类图书的视图Computer-BOOK，并要求进行修改、插入操作时保证该视图只有计算机类的图书。实现上述要求的SQL语句如下：
    CREATE  （）
    AS SELECT图书编号，图书名称，作者，出版社，出版日期
    FROM图书
    WHERE图书类型=＇计算机＇
    （）；
 

某企业有生产部和销售部，生产部负责生产产品并送入仓库，销售部从仓库取出产品销售。假设仓库可存放n件产品。用PV操作实现他们之间的同步过程如下图所示。
其中，信号量S是一个互斥信号量，初值为（）； S1是一个（）；S2是一个（）。

假设关系R1和R2如下图所示：

若进行R1∞R2运算，则结果集分别为（）元关系，共有（）个元组。

某企业有生产部和销售部，生产部负责生产产品并送入仓库，销售部从仓库取出产品销售。假设仓库可存放n件产品。用PV操作实现他们之间的同步过程如下图所示。
其中，信号量S是一个互斥信号量，初值为（）； S1是一个（）；S2是一个（）。

已知关系模式：图书（图书编号，图书类型，图书名称，作者，出版社，出版日期，ISBN），图书编号唯一识别一本图书。建立“计算机”类图书的视图Computer-BOOK，并要求进行修改、插入操作时保证该视图只有计算机类的图书。实现上述要求的SQL语句如下：
    CREATE  （）
    AS SELECT图书编号，图书名称，作者，出版社，出版日期
    FROM图书
    WHERE图书类型=＇计算机＇
    （）；

某企业有生产部和销售部，生产部负责生产产品并送入仓库，销售部从仓库取出产品销售。假设仓库可存放n件产品。用PV操作实现他们之间的同步过程如下图所示。
其中，信号量S是一个互斥信号量，初值为（）； S1是一个（）；S2是一个（）。

分配给某公司网络的地址块是220．17．192．0／20，该网络被划分为（）个C类于网，不属于该公司网络的子网地址是（）。

Computers will become more advanced and they will also become easier to use.
Improved speed recognition will make the operation of a computer easier. Virtual reality（虚拟现实）， the technology of（） with a computer using all of the human senses， will also contribute to better human and computer（）. Other， exotic （奇异的） models of computation are being developed， including biological computing that uses living organisms， molecular computing that uses molecules with particular（）， and computing that uses DNA， the basic unit of heredity（遗传）， to store data and carry out operations. These are examples of possible future computational platforms that， so far， are limited in abilities or are strictly（） . Scientists investigate them because of the physical limitations of miniaturizing circuits embedded in silicon. There are also（） related to heat generated by even the tiniest of transistors.

 分配给某公司网络的地址块是220．17．192．0／20，该网络被划分为（）个C类于网，不属于该公司网络的子网地址是（）。

Computers will become more advanced and they will also become easier to use.
Improved speed recognition will make the operation of a computer easier. Virtual reality（虚拟现实）， the technology of（） with a computer using all of the human senses， will also contribute to better human and computer（）. Other， exotic （奇异的） models of computation are being developed， including biological computing that uses living organisms， molecular computing that uses molecules with particular（）， and computing that uses DNA， the basic unit of heredity（遗传）， to store data and carry out operations. These are examples of possible future computational platforms that， so far， are limited in abilities or are strictly（） . Scientists investigate them because of the physical limitations of miniaturizing circuits embedded in silicon. There are also（） related to heat generated by even the tiniest of transistors.

Computers will become more advanced and they will also become easier to use.
Improved speed recognition will make the operation of a computer easier. Virtual reality（虚拟现实）， the technology of（） with a computer using all of the human senses， will also contribute to better human and computer（）. Other， exotic （奇异的） models of computation are being developed， including biological computing that uses living organisms， molecular computing that uses molecules with particular（）， and computing that uses DNA， the basic unit of heredity（遗传）， to store data and carry out operations. These are examples of possible future computational platforms that， so far， are limited in abilities or are strictly（） . Scientists investigate them because of the physical limitations of miniaturizing circuits embedded in silicon. There are also（） related to heat generated by even the tiniest of transistors.

Computers will become more advanced and they will also become easier to use.
Improved speed recognition will make the operation of a computer easier. Virtual reality（虚拟现实）， the technology of（） with a computer using all of the human senses， will also contribute to better human and computer（）. Other， exotic （奇异的） models of computation are being developed， including biological computing that uses living organisms， molecular computing that uses molecules with particular（）， and computing that uses DNA， the basic unit of heredity（遗传）， to store data and carry out operations. These are examples of possible future computational platforms that， so far， are limited in abilities or are strictly（） . Scientists investigate them because of the physical limitations of miniaturizing circuits embedded in silicon. There are also（） related to heat generated by even the tiniest of transistors.

Computers will become more advanced and they will also become easier to use.
Improved speed recognition will make the operation of a computer easier. Virtual reality（虚拟现实）， the technology of（） with a computer using all of the human senses， will also contribute to better human and computer（）. Other， exotic （奇异的） models of computation are being developed， including biological computing that uses living organisms， molecular computing that uses molecules with particular（）， and computing that uses DNA， the basic unit of heredity（遗传）， to store data and carry out operations. These are examples of possible future computational platforms that， so far， are limited in abilities or are strictly（） . Scientists investigate them because of the physical limitations of miniaturizing circuits embedded in silicon. There are also（） related to heat generated by even the tiniest of transistors.