问题 问答题

某局域网采用CSMA/CD协议实现介质访问控制,数据传输速率为10Mbps,主机甲和主机乙之间的距离为2km,信号传播速度是200000km/s。请回答下列问题,并给出计算过程。

若主机甲和主机乙发送数据时发生冲突,则从开始发送数据时刻起,到两台主机均检测到冲突时刻止,最短需经过多长时间最长需经过多长时间(假设主机甲和主机乙发送数据过程中,其他主机不发送数据)

答案

参考答案:当甲乙同时向对方发送数据时,两台主机均检测到冲突所需时间最短:


当一方发送的数据马上要到达另一方时,另一方开始发送数据,两台主机均检测到冲突所需时间最长:

完形填空

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、正确形式,使对话通顺。

W:Oh,did you really like it?

M:Yes,very much.It was excellent!

W:Well,thank you for(77)s________ so.                                                    77.              

M:In fact,could I (78)a_________you for the recipe(烹饪方法)?                 78.              

W:  (79)S_________.It’s really very easy                                                 79.              

(80)F_________,mix together one egg, two teaspoons of salt,                 80.              

and two pounds of ground beef.(81)T__________,add twelve                      81.              

ounces milk an a cup of bread crumbs(面包屑). Are you with me so far? 

M:Yes,I’m with you

W:Okay.(82)N___________,put the mixture into a baking pan And              82.              

(83)a_________that,bake an hour and fifteen minutes at 350 degrees.        83.              

M:Wait a minute!I didn’t get the last (84)s________.Could you repeat          84.              

that part?

W:Sure.Bake an hour and fifteen minutes at 350 degrees.

M:Now I’ve got it.Is that it?

W:Yes.That’s it!

M:Thanks very much.

W:My(85)p____________.                                                                       85.              

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