问题 单项选择题

在Ethernet交换机的帧转发方式中,交换延时最短的是( )。

A.直接交换方式

B.存储转发交换方式

C.改进的直接交换方式

D.以上都不是

答案

参考答案:A

解析: Ethernet交换机的帧转发方式可以分为3类:直接交换方式、存储转发交换方式、改进的直接交换方式。直接交换方式的优点是交换延迟时间短,缺点是缺乏差错检测能力,不支持不同输入输出速率的端口之间的帧转发。存储转发交换方式的优点是具有差错检测能力,并能支持不同输入输出速率的端口之间的帧转发,缺点是交换延迟时间将会增长。改进的直接交换方式的交换延迟时间介于前两者之间。

阅读理解

第三部分:阅读理解:(共20小题;每小题2分,满分40分)阅读下列短文,从每题所给的四个选项中,选出最佳选项。

(A)

What makes a house a home? A home is a place of companionship with people in it who love each other, who are harmonious (和谐的) and closer with one another than with those in the workplace or with classmates at school. A home is a place that’s so magnetic(有吸引力的) that it’s difficult to leave. In a home there is love, sharing and appreciation, and the members help one another.

I have seen families on the street. But if they live, sleep, talk, and eat together, they are a family, even if they are poorly off. You don’t need a roof to make a home. The truly homeless are some of the rich people who build multi-million-dollar houses and are too busy to really live in them. The truly homeless are those who have turned their home into a hotel lobby. The parents work and the children misbehave. They don’t talk and eat together every day. They rarely see each other. The truly homeless people are those with babysitters, caretakers, gardeners and maids. However, people are unaware of this, as they are too busy making money outside the home that they don’t live in. This is another way of looking at the rich and the homeless. Who is to be pitied?

Control of the computer and the Internet is also important to make a house into a home. If the computer is on all the time, the house turns into an office, even if everyone is at home. Many homes these days are just offices. Human communication has stopped. The computer eats up all the time that one should be giving to others within the home. Using the computer moderately gives us time for play and communication, not with a screen, but with other people.

56. Which of the following may serve as the best title for this passage?

A. How to make a house a home?

B. What makes a house a home?

C. Who are truly homeless?

D. What is a home for?

57. The purpose of the first paragraph is to _________.

A. tell us that where there is home there is love

B. tell us what people think a home is

C. tell us the author’s concept(理解)of home

D. tell us how to have a happy home

58. The underlined word “those” refers to ________.

A. people who build multi-million-dollar houses

B. people who have lost their family members

C. people who don’t spend time with the family

D. homeless families living on the street in America

59. Which of the following is FALSE according to the passage?

A. A home is a place where you are willing to stay.

B. Even the poorest people can have a happy home.

C. Computers and the Internet are important for a happy home.

D. Sometimes it’s the rich that should be pitied.

单项选择题