问题 单项选择题

IEEE 802.5令牌环(Token Ring)网中,时延是由 (1) 决定。要保证环网的正常运行,环的时延必须有一个最低限度,即 (2) 。如果达不到这个要求,可以采用的一种办法是通过增加电缆长度,人为地增加时延来解决。

设有某一个令牌环网长度为400m,环上有28个站点,其数据传输率为4Mbit/s,环上信号的传播速度为200m/μs,每个站点具有1bit时延,则环上可能存在的最小和最大时延分别是 (3) bit和 (4) bit。当始终有一半站点打开工作时,要保证环网的正常运行,至少还要将电缆的长度增加 (5) m。

4()

A.9

B.28

C.36

D.48

答案

参考答案:C

问答题

阅读短文,并按照题目要求用英语回答问题。

I’m a 34-year-old man, married, lived in a nice house, and have a successful career as an educational consultant. But my life was not always so great. I had a learning disability from an early age. I went to a special school where I got plenty of extra help. Still, I suffered the rest of my school days in public schools.

My life improved remarkably when I discovered art. The art world gave me a chance to express myself without words. I went to a workshop and gradually got good at making things with clay(黏土). Here I learned my first important lesson: disabled as I was in language. I could still be smart and well express myself with clay. And my confidence came along.

I got my next lesson from rock climbing. It was a fun thing but I was scared from the start. I soon noticed it wasn’t a talent thing; it was practice. So I did it more. After about five years of climbing, I found myself in Yosemite Valley on a big wall. I learned that if you fall in love with something and do it all the time, you will get better at it.

Later I decided to apply my previous experience to learning how to read and write. Every day I practiced reading and writing, which I used to avoid as much as possible. After two hard years, I was literate.

Having gone through the long process with art, rock climbing, and reading and writing, now I’ve got to a point in my life where I know I am smart enough to dive into an area that is totally unknown, hard, but interesting.

 

Why did art give the author confidence? (No more than 10 words)

多项选择题