问题 单项选择题

ATM适配层的功能是( )。

A.比特定时
B.信元校验
C.分割和合并用户数据
D.信元头的组装和拆分

答案

参考答案:C

解析: TM适配层(AAL)负责处理高层来信息,发送方把高层的数据分割成48字节长的ATM负载,接收方把ATM信元的有效负载重新组装成用户数据报。

完形填空
完型填空。
    When you look into the sky at night, you can see a large number of stars. Besides,
you can see the   1   too. It's bright   2   beautiful. People write many songs and
poems (诗歌)   3   it.
    In the 1960s, some   4   wanted to be the first one to send a man to the moon.
America and Russia were in this "space race". They   5   a lot of money   6   it.
The   7   man in space was Yuri Gagarin, a Russian. He went into the space   8   1961.
A few years later, an American spaceship flew to the moon. Neil Armstrong walked out.
He was the first man   9   on the moon.
    China is interested in the space too. In 2003, Yang Liwei, China's hero, flew  10  
the earth in space.
( )1. A. moon     
(     )2. A. but      
(     )3. A. on       
(     )4. A. country  
(     )5. A. spend    
(     )6. A. on       
(     )7. A. first    
(     )8. A. on       
(     )9. A. walk     
(     )10. A. around  
B. sun       
B. and       
B. about     
B. city      
B. spent     
B. in        
B. second    
B. at        
B. walking   
B. to        
C. earth    
C. or       
C. of       
C. cities   
C. cost     
C. to       
C. third    
C. in       
C. to walk  
C. towards  
D. stars       
D. /           
D. from        
D. countries                  
D. took        
D. about       
D. fourth      
D. of          
D. walks       
D. through     
多项选择题