问题 单项选择题

在网络安全中,截取是指未被授权的实体得到了资源的访问权。这是对( )。

A.可用性的攻击

B.完整性的攻击

C.保密性的攻击

D.真实性的攻击

答案

参考答案:C

解析: 安全攻击的类型主要有四种:中断、截取、修改和捏造。中断是指系统资源造到破坏和变得不能使用,这是对可用性的攻击。截取是指未被授权的实体得到了资源的访问权,这是对保密性的攻击,未授权实体可以是一个人、一个程序或一台计算机。修改是指未被授权的实体不仅得到了访问权,而且还篡改了资源,这是对完整性的攻击。捏造是指未被授权的实体向系统中插入伪造的对象,这是对真实性的攻击。

阅读理解

阅读理解。

     Photographs are everywhere. They decorate (装饰) the walls of

homes and are used in stores for sales of different goods. The news

is filled with pictures of fires, floods, and special events. Photos record

the beauties of nature.They can also bring things close that are

far away. Through photos, people can see wild animals, cities in foreign

lands, and even the stars in outer space. Photos also tell stories.

     Reporting the news through photos is called photojournalism.

At times photojournalists tell their stories through a single picture.

At other times, they use a group of pictures to tell a story. Each picture

is like a chapter in a book, which can do more than record the

facts. It can also be a strong force for social change.

     Jacob Riis was among the first photojoumalists. He took pictures

of parts of New York City where the poor lived. Riis believed

that poverty(贫穷 )caused crime, and he used photos to help him

prove his point. A few years later,the photos of small children working

in factories by Lewis Hine shocked the public. Hine's pictures

helped bring about laws to protect such children.

     Hundreds of pictures may have to be taken in order to get one

or two really good photos. It takes science to have the photo come

out clearly and art to make a photo that has a good design and expresses

feeling. Photojournalists make an actual record of what they

see. A photo, however, can be both a work of art and an actual record.

It can record an important event as a beautiful or exciting picture.

     As historical and artistic documents (文献), photos can become

more important over time. Today photojournalists still have

their pictures appear in newspapers and magazines. They also publish

(发表) them in books and on the Internet.

1. The underlined word"They" in the first paragraph refers to __.  

A. beauties  

B. photos      

C. goods      

D. events

2. The photos of the small children by Hine show us that photos __.   

A. are also works of art

B. are popular ways of reporting news

C. often shock the public

D. can serve as a force for social change

3. What can we learn from the passage?   

A. News with pictures is encouraging.

B. Photos help people improve their life.

C. News photos mean history in a sense.

D. People prefer to read news with pictures.

 4 The text is mainly about __. 

A. telling the story through pictures

B. decorating the walls of homes

C. publishing historical papers

D. expressing feeling through pictures

单项选择题