题目内容
在关系代数中，从两个关系的笛卡尔积中选取它们的属性或属性组问满足一定条件的元组得到新的关系的操作称为【 】。
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某部门网络管理员使用DHCP服务器对公司内部主机的IP地址进行管理，已知：
①该公司共有40个可用IP地址为202.112.11.11～202.112.11.50。
②DHCP服务器使用Windows2003操作系统，其IP地址为202.112.11.11。
③连接该子网络路由器端口的IP地址为202.112.11.12。
④DHCP客户端使用WindowsXP操作系统。
请回答下列问题：
(1) 配置DHCP服务器作用域时，起始IP地址输入“202.112.11.11
11.
Go into any average provincial town and the last thing you will
find is a decent book-shop. More than one great industrial town of
a population of over a hundred thousand has only one such shop,
and that is generally kept going by the sale of school-books.
It is because we cannot afford to buy books. We spend six 【S1】______
hundred million pounds a year on the beer, but we certainly do not 【S2】______
spend six hundred million pence on literature. Many people can 【S3】______
afford to buy motor-cars with anything from seven hundred pounds 【S4】______
would be aghast at the idea of spending a single pound occasionally
on a book. Yet, merely like furniture, books are a cheaper and 【S5】______
better decoration than blue chinas or the eighteenth century chairs. 【S6】______
They are better because they put out the stamp of individuality 【S7】______
upon a house. The desire of the eighteenth century chairs and blue 【S8】______
china may represent not as a genuine personal taste for beautiful 【S9】______
things, but an artificial passion for rare and expensive ones. On
the other hand, a collection of books will give a house character
and meaning. It should tell you about its. 【S10】______
【S1】
如图3-4所示为在一台主机上用Sniffer捕捉的数据包，其中数据包标号[No.]为“7”的条目中[Summary]栏中的部分信息被隐去。请根据图3-4显示的信息回答下列问题：
(1) 该主机正在访问的WWW服务器IP地址是 (16) 。
(2)根据图3-4中[No.]栏中标号，表示TCP连接3次握手过程开始的数据包的标号是 (17) 。
(3)标号为“7”的数据包的源端口号应为 (18) ，该数据包TCPFlag的ACK位应 (19) 。
(4)标号为“7”的数
16.
？Read the text below about how to order products.
？In most of the lines (41-52) there is one extra word. It is either grammatically incorrect or does not fit in with the sense of the text. Some lines, however, are correct.
？If a line is correct, write CORRECT on your Answer Sheet.
？If there is an extra word in the line, write the extra word in CAPITAL LETTERS on your Answer Sheet.
Special Products Co.—How to Order
Our specialty is our convenient catalogue system. Instead of spending time going to a shop, you simply order with it directly from us.
41．Ordering is easy and delivery fast. Once received, your order will
42．normally be dispatched within 72 hours. We will inform. to you
43．immediately should any items be out of stock. If you are not happy
44．with your purchases please return them to us within the 15 days in their
45．original packaging and we will return you for in full. Quality is our main
46．criterion. Each item is under unconditionally guaranteed for 6 months.
47．You will receive a receipt and with your order which is your guarantee.
48．In the unlikely event of damage to an item during delivery, should please
49．contact with us immediately on 56513726 and we will arrange for
50．its return or replacement.
51．All prices and promotional
52．offers are valid until 30th September.
(41)
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