问题 单项选择题

下面关于ATM技术说法正确的是( )。

A.ATM的中文名称是同步数字系统

B.ATM技术适合低带宽和高时延的应用

C.ATM信元中,前两个字节是信头

D.ATM协议本身不提供差错控制

答案

参考答案:D

解析:[分析] ATM是异步传输模式,它特别适合高带宽和低时延应用:仅仅把数据从一个端点传输到另一个端点,它本身并不提供差错恢复。ATM信元由53字节组成:前5个字节是信头,其余48字节是信息字段。

阅读理解

阅读下列短文,从各题A、B、C、D中选出能回答所提问题或完成所给句子的最佳答案。

      It is Sunday afternoon. Mary goes to do the shopping with her mother. Her mother wants to buy some

  food for supper. Mary wants to buy a new skirt and some school things. They come to a shop.

     "What does your shop sell?"  Mary asks, "A lot of things." The girl in the shop says. "You can buy

 food, drinks, clothes in our shop and school things, too."

     Mary and her mother go in. There are many people in the shop. Mary looks at a nice white skirt.

     "How much is the skirt?" Mary asks the girl in the shop.

     "It's eighty yuan."

     "That's too dear."

     "What about the green one? It looks nice. And it's only thirty yuan."

     "OK, thanks a lot."

     "You are welcome."

     After that, Mary buys some school things, too. Here mother buys a lot of food, like bread, cakes, meat

  and fish. They get home very late.

1. Mary goes to do the shopping with her mother on _____.

     A. Saturday afternoon      

     B. Saturday morning

     C. Sunday morning      

     D. Sunday afternoon

2. Mary wants to buy a new skirt and _____.

     A. some food

     B. some drinks

     C. come clothes

     D. some school things

3. The white skirt is _____.

    A. ¥30

    B. ¥110

    C. ¥80

    D. ¥100

4. Mary buys a _____ skirt.

    A. white

    B. green

    C. red

    D. dear

5. The green skirt is _____.

    A. nice and cheap          

    B. nice but dear

    C. not nice but cheap        

    D. not nice or cheap

填空题