试题与答案

为了使终端设备的数据能够可靠地进行发送和接受,数字用户电路要求必须具备什么功能?

题型:问答题 论述题

题目:

为了使终端设备的数据能够可靠地进行发送和接受,数字用户电路要求必须具备什么功能?

答案:

参考答案:

1提供两个双向传输数字话音或数据的基本通道,一个双向传输控制信号和低速数据的信号通道D;

2具有对2B+D线路的启动和停止功能;

3将B通道和D通道分开,并进行链路口规范处理;

4通过D通道将终端送来的信号送到交换机控制系统和信号系统进行相应处理;

5路由寻找和为B和D通道进行路由选择;

6对每条数字线路可进行单独测试,维护和特殊保护;

7其它如何回声抑制,过压保护,线路馈电及故障检测等功能;

试题推荐
题型:阅读理解

阅读理解。

     During his life Dr James Naismith worked as a doctor, taught P.E and wrote several books. While he never

thought it very important, Dr Naismith is today best known for one thing. He was the inventor of basketball.   

     Dr James Naismith was born in Canada in 1861 and his first job was at a special sports school in the USA.

One day the school principal told James he was having a problem with the students. Because of heavy snow,

the students could not go outside. He told James that they needed a sport the boys could play indoors and gave

the teacher two weeks to think of something.   

     It was on the very last day that James came up with his idea. The "birth of basketball" is said to be on

December 21, 1891, when two teams from the school played the first game. It was quite different from the

basketball games of today. It had 9 players on each team and footballs were used instead of basketballs. Soon

after, the game changed to 5 players on each side, using special"basketballs" through nets.   

     Although Dr Naismith did not live to see basketball become the worldwide game it is today, in 1936, just

three years before his death, basketball became an Olympic sport at the games in Berlin.

1. Which of the following things did Dr James Naismith NOT do?

A. Teach P.E in school.

B. Write some books.

C. Work at hospital.

D. Take part in the Olympic Games.

2. In which season did Dr Naismith invent basketball?

A. Summer.

B. Winter.

C. Spring.

D. Autumn.

3. Why is December 21 thought to be the birthday of basketball?  

A. It was on this day that Dr Naismith came up with his idea for basketball.  

B. It was the day on which Dr Naismith was born.  

C. It was the day on which Dr Naismith was asked by his boss to invent a new game.  

D. It was on this day that the first game of basketball was played.

4. At the time of Dr Naismith's death, which of the following was true?

A. Basketball was already a worldwide game.

B. Basketball was played with 9 players on each side.

C. Basketball was an Olympic sport.

D. Basketball was still played using footballs. 

5. What would be the best title for this story?

A. History of Basketball

B. How Basketball Has Changed

C. Father of Basketball

D. Happy Birthday, Basketball

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