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问题 单项选择题

在分布式数据库的数据分配策略中，若全局数据存在多个副本，且在每个物理场地都保存一个完整的数据副本，则该策略属于______。

A．集中式策略

B．分割式策略

C．全复制式策略

D．混合式策略

答案

参考答案：C

解析： 全复制式策略指在分布式数据库的数据分配策略中，全局数据存在多个副本，且在每个物理场地都保存一个完整的数据副本。因此本题答案为C。

单项选择题

Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (6) from a friend who asks you to open it. This is what happens with Melissa and several other similar email (7) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’address book, previous emails, web pages (8) .
As administrators seek to block dangerous email attachments through the recognition of well-known (9) , virus writers use other extensions to circumvent such protection. Executable(.exe)files are renamed to .bat and .cmd plus a whole list of other extensions and will still run and successfully infect target users.
Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwouds and give the (10) access to your network.

A．names

B．cookies

C．software

D．extensions
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单项选择题

女性，28岁，既往有关节痛史，劳累后心悸、气短3年，下肢水肿3个月。X线示左右心室扩大，左房增大，食管局限性压迹，血压130/50mmHg，有枪击音。最可能的诊断是（）

A.风湿性心脏病二尖瓣狭窄兼关闭不全

B.风湿性心脏病二尖瓣狭窄

C.风湿性心脏病二尖瓣狭窄，主动脉瓣关闭不全

D.风湿性心脏病主动脉瓣关闭不全

E.心肌病
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