问题 问答题 简答题

简述通信系统需要完成的任务。

答案

参考答案:

通信系统需要完成的任务如下。

(1)信号接口:产生或接收符合通信协议的信号。

(2)路由和寻址:为发出信号选择到达目的地的路径。

(3)呼叫和应答:信号发送前先呼叫,接收方应答后建立通信链路,这个过程叫握手。

(4)可靠传输:采用各种措施保证数据传输的正确性。

问答题
阅读理解

There’s been a lot of talk about white-and-blue collar(衣领) workers, and you may have even heard of gold collar workers, but lately a new color of collar is making its way into China’s urban vernacular(土话)—green. Green collars say no when work is life and life is work. They choose to get out of the fast lane(车道), and explore new ways of living “green”.

Living green doesn’t mean someone is working as an environmentalist, biologist or scientist. Instead it is more of a lifestyle choice. A typical green collar is well educated like a white-collar but physically tough like a blue-collar, likely born in the 70s or 80s of the last century and living in one of China’s big cities, with a monthly income well above 5,000 yuan(about US $700).

The life of a green collar may go something like this: Turn off the mobile phone after work, eat only healthy food rich in vitamins, go on hikes every weekend, and like to help the underprivileged.

Green collars even have their own club. In Beijing, the Green Collar Club is for people who share a “be happy, healthy and helpful” spirit. The club often holds charity parties and uses the donations for environmental protection and poverty relief projects in China.

“They are successful in their careers, but do not miss the pleasures in life. They have a lot of money, but do not fall slave to it.” said Zuo Shiguang, one of the founding members of the club.

小题1:What is the passage mainly about?

A.Differences between white-and-blue collars and green collars.

B.The increasing awareness(意识) of environmental protection.

C.New trends of life in China’s big cities.

D.The lifestyle of green collars.小题2:Green collars are living green because _________.

A.they have a large income to use

B.they refuse to live an unhealthy life

C.they spend a lot of money and time in the open air

D.they devote themselves to environmental protection小题3:What’s Zuo Shiguang’s attitude towards green collars?

A.Appreciative.

B.Doubtful.

C.Negative(否定的).

D.Neutral(中立的).小题4:The underlined part “the underprivileged” probably refers to those who are_________.

A.in heavy polluted areas

B.in faraway places

C.in a poor state of education

D.in unfavourable(不利的) conditions