问题 单项选择题

在 ISO/OSI 参考模型中,网络层的主要功能是______。

A.组织两个会话进程之间的通信,并管理数据的交换

B.数据格式变换、数据加密与解密、数据压缩与恢复

C.路由选择、拥塞控制与网络互连

D.确定进程之间通信的性质,以满足用户的需要

答案

参考答案:C

解析:网络层的功能是在信源和信宿之间建立逻辑链路,为报文或报文分组的传递选择合适的路由以实现网络互联。为进行路由选择,要选择合适的路由选择算法,并针对网络情况实现拥塞控制。

写作题

Most people feel lonely sometimes, but it usually only lasts between a few minutes and a few hours. This kind of loneliness is not serious. In fact, It is quite normal. For some people, though, loneliness can last for years. Psychologists are studying this complex phenomenon in an attempt to better understand long-term loneliness. These researchers have already identified three different types of loneliness.

The first kind of loneliness is temporary. This is the most common type. It usually disappears quickly and does not require any special attention.

The second kind, situational loneliness, is a natural result of a particular situation ---for example, a divorce, the death of a loved once, or moving to a new place. Although this kind of loneliness can cause physical problems, such as headaches and sleeplessness, it usually does not last for more than a year. Situational loneliness is easy to understand and to predict.

The third kind of loneliness is the most severe. Unlike the second type, chronic loneliness usually lasts more than two years and has no specific cause. People who experience habitual loneliness have problems socializing and becoming close to others. Unfortunately, many chronically lonely people think there is little or nothing they can do to improve their condition.

[写作内容]:

1) 以约30词概括短文的要点;

2) 以约120词就“孤独”这一话题谈谈你的看法,并包括以下要点:

a. 描述你感到孤独的某个时刻;

b. 解释你为什么觉得孤独,你怎样排除孤独感;

c. 根据你的经历,给出排除孤独的建议。

[写作要求]:

1. 可以使用实例或其他论述方法支持你的论点,也可以参照阅读材料的内容,但不得

直接引用原文中的句子;

2.作文中不能出现真实姓名和学校名称。

[评分标准]:

概括准确、语言规范、内容合适、篇章连贯。

问答题