以下关于公钥基础设施概念的描述中,错误的是()。 A.为用户建立一个安全的物联网运行

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问题:

以下关于公钥基础设施概念的描述中,错误的是()。

A.为用户建立一个安全的物联网运行环境,使用户能够方便地使用数字签名技术

B.保证物联网上数据的机密性、完整性与不可抵赖性

C.PKI包括认证与注册认证中心、策略管理、密钥与证书管理、密钥备份与恢复等

D.PKI系统中的信息需要用户定期维护

考点:物联网技术与运用物联网技术与运用题库
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果园里梨树与桃树的比是3:5,已知桃树有40棵.这个果园共有果树多少棵?

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阅读理解

     Our children and grandchildren may not have a chance to visit many of the most famous places around

the world. War, weather, age, traffic and pollution damage these famous places. Looking after these places often costs more than one country can afford.

     In the early 1970s, world governments decided that if they joined together, they would be able to

preserve our history. If every country paid some money, they said, it would be possible to look after

important historic places. Also, if they discovered that a monument needed urgent help, they would have

money for repairs. For these reasons, countries around the world united to form the World Heritage

Organization in 1972. Today, the organization helps to maintain and restore the most important places from our history.

     However, one of the biggest problems for historic places is vandalism. People sometimes enter the sites and destroy or damage the buildings. At some sites, such as Stonehenge(巨石阵) in England, governments have built high fences to protect the site from vandals.

     There are many different ideas about how to solve the problem of vandalism. Stone experts say that if

guards patrolled the sites, vandals would not be able to get in. Some experts say that if they fixed more

television cameras, they would not need so many guards. Other experts say that the best solution is

education. If people learned to respect history, they would not destroy or damage it. They would also want to spend money looking after old places. For this reason, the World Heritage Organization helps to spread information about the value of historic sites.

1. According to this passage, ____ is NOT mentioned in Paragraph 1 for the reasons why the famous

places are damaged?  

A. people's awareness            

B. pollution  

C. war and climate              

D. traffic

2. Which of the following shows us the action of vandalism?

A. Governments build high fences to protect the site from vandals

B. Guards patrolled the sites and they fixed more television cameras

C. People enter the sites and cause damage to the buildings

D. They collect as much money as they can to preserve the buildings

3. What's the best way to solve the biggest problem of preserving our history?

A. Every country spends more money looking after these places

B. To form the World Heritage Organization

C. Too many guards are needed to prevent vandals getting in

D. To make people know more about the value of historic sites

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抵押协议一旦正式签署,立即生效。()

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《汉书》:“下无倍畔之心,上无诛伐之志。”颜注:“倍()背。”

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控制水痘传播的主要措施有哪些()

A.隔离水痘病人至皮疹完全结痂或出疹后7天

B.易感人群积极使用抗病毒药物

C.消毒水痘病人的分泌物污染物品

D.必要时向易感人群提供被动或主动免疫预防感染

E.带状疱疹病人也应该严密隔离

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