问题 单项选择题

以下关于网络结构与拓扑构型设计方法的描述中,错误的是 (18)

A.核心层网络用于连接分布在不同位置的子网,实现路由汇聚等功能
B.汇聚层根据接入层的用户流量,进行本地路由、安全控制、流量整形等处理
C.接入层网络用于将终端用户计算机接入到网络之中
D.核心层设备之间、核心层设备与汇聚层设备之间通常采用冗余链路的光纤连接

答案

参考答案:A

解析: 通常,大中型网络系统采用分层的设计思想,可以方便地分配与规划带宽,有利于均衡负荷,提高网络效率,是解决网络系统规模、结构和技术的复杂性的有效方法。大中型企业网、校园网或机关办公网基本上都采用3层网络结构。其中,核心层网络用于连接服务器集群、各建筑物子网交换路由器,以及与城域网连接的出口;汇聚层网络用于将分布在不同位置的子网连接到核心层网络,实现路由汇聚的功能;接入层网络用于将终端用户计算机接入到网络之中。
通常,核心层设备之间、核心层设备与汇聚层设备之间直接使用具有冗余链路的光纤连接;汇聚层设备与接入层设备之间、接入层设备与用户计算机之间可以视情况而选择价格低廉的非屏蔽双绞线(UTP)连接。

阅读理解

阅读理解。

Dear editor,

     I read with interest the article on American families. In general I agree with it, but there are some important

things it left out. It didn't tell the reader much about the life of a househusband. It's not an easy life. I know,

because I'm now a househusband myself. A househusband has to change many of his ideas and his ways.

     First of all, he has to change the way he thinks about time. Before I was a househusband, I worked full-time

for the New York Times. I was a reporter, and time was always important. Everyone was always in a hurry.

     However, it's different at home. The househusband cannot be in a hurry all the time. If you rush around,

you will make everyone unhappy because they don't understand. For them, time is not important. So you have

to learn to slow down. That is the first and most important rule for a househusband.

     What's more, there is something else the househusband must learn. You must learn to show how you feel

about things. Many men do not know how to talk about their anger, worries, or love. But children need to know

how much you love them. If you are angry, they need to know why. So does your wife. If you do not say

anything, your family may get the wrong idea. Then there may be serious problems.

     People talk a lot about househusbands these days. Usually they talk about men doing the housework, the

cooking, cleaning, and shopping. But in my opinion, these are the easiest things to learn. It is much harder for

me to change the way I think and the way I act with my family. I think other men will also find this harder,

but, like me, will find it necessary if they want to have a happy family! 

                                                                                                                             Ted Diamond

                                                                                                                             Hartwell, New Jersey

1. The text is mainly about ____.

A. fathers and children

B. life as a househusband

C. ideas about time

D. American families

2. Family problems can occur if ____.

A. men get wrong ideas about something

B. men talk too much with their families

C. men don't talk enough with their families

D. people talk a lot about househusbands

3. Ted thinks ____.

A. learning about housework is easy

B. learning about housework is a problem

C. being a househusband is an easy task

D. cooking is the easiest thing to learn

4. How is the text developed?

A.  B.  C.  D.

(① = paragraph l; ② = paragraph 2; ③ = paragraph 3;

④ =paragraph 4; ⑤ = paragraph 5)

多项选择题