问题 单项选择题

信息认证主要是验证

A.信息发送者的真实性和信息的完整性

B.信息传输过程中是否出错

C.信息中是否有误码

D.信息传输的速率

答案

参考答案:A

解析: 信息认证,首先是验证信息的发送者的真实性,即不是假冒的;其次是验证信息的完整性,即验证信息在传输或存储过程中未被篡改、重放或延迟等。因此信息认证主要是验证信息发送者的真实性和信息的完整性。

阅读理解

阅读理解

     It was a dark and cold night. The taxi driver didn't have even one passenger all day. When he went by

the railway station, he saw a young man coming out with two bags in his hands. So he quickly opened the

door of the car and asked, "Where do you want to go, sir?"

     "To Star Hotel," the young man answered. When the taxi driver heard this, he didn't feel happy any more.

He knew the young man could give him only three dollars because the hotel was not far from the railway

station. But suddenly, he had an idea. He took the passenger through many streets of the big city.

     After a long time, the car arrived at the hotel at last."You should pay me fifteen dollars," the driver said to

the young man."What? Fifteen dollars! Do you think I'm a fool? Only last week, I took a taxi from the railway

station to this same hotel and I only gave the driver thirteen dollars. I know how much I have to pay for the

trip. I won't pay you one dollar more than I paid to the other taxi driver last week."

1. How did the taxi driver feel when he knew where the young man wanted to go? 

    _____________________________________________________________

2. Who cheated (欺骗) the young man, the first taxi driver or the second one? 

    _____________________________________________________________

3. How much did the young man want to pay? 

    _____________________________________________________________

4. What do you think of the two taxi drivers? 

    _____________________________________________________________

5. 将文中画线部分的句子翻译成汉语。

    _____________________________________________________________

单项选择题