问题 单项选择题

一旦介质空闲就发送数据,假如介质是忙的,继续监听,直到介质空闲后立即奉送数据;如果有冲突就退避,然后再尝试的退避算法称为()算法。

A.非坚持CSMA

B.1-坚持CSMA

C.P-坚持CSMA

D.Y-坚持CSMA

答案

参考答案:B

解析:

CSMA (载波监听多路访问) 控制策略中有3种坚持退避算法,其中一种是:“一旦介质空闲就发送数据,假如介质是忙的,继续监听,直到介质空闲后立即奉送数据;如果有冲突就退避,然后再会试”的退避算法称为1-坚持CSMA算法。这种算法的主要特点是介质利用率高,但无法避免冲突。CSMA/CD在CSMA的基础上增加了冲突检测功能。

完形填空

第Ⅱ卷(共35分)

第四部分:写作(共两节,满分35分)

第一节:对话填空(共10小题;每小题1分,满分10分)

阅读下面对话,掌握其大意,并根据所给首字母的提示,在标有题号的右边横线上写出一个英语单词的完整、正确的形式,使对话通顺。

(M="Man      " W=Woman)

W: Good morning, Dr. Brown. Good to see you again.

M: Well, I have to be down in New York at the end of this week.

Is there still any (76)r_______ on any of the flight?                                 76__________

W: I’ll see. When do you want to leave?

M: Friday night or Saturday morning at the (77)l________ .                      77__________

W: I’ll see what’s available. Yes. There are still a few (78)s_______                78__________

available. But it’s the last flight on Friday night (79)l_______ here                 79__________

at 10:15.

M: When would we (80)a________ in New York?                                   80__________

W: Just after midnight.

M: Not ideal, but could not be worse. Reserve a seat for me on that one, then.

W: Gladly. Are you (81)t_______ for business and pleasure?                           81__________

M: I’m supposed to (82)a_______ a medical conference at the weekend,         82__________

but I hope I’ll have a (83)c_______ to get in some jazz, too. I’ve                   83__________

always been a great jazz (84)f_______.                                           84__________

W: OK. I’ve (85)m_______ your reservation. Have a good trip.                  85__________

M: Thank you.

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