问题 单项选择题

以下关于IEE802.3ae标准的描述中,错误的是 (8)

A.支持IEEE 802.3标准中定义的最小和最大帧长

B.支持IEEE 802.3ad链路汇聚协议

C.使用10um单模光纤作为传输介质,光纤最大长度可达40km

D.使用50um多模光纤作为传输介质,光纤最大长度可达10km

答案

参考答案:D

解析:[要点解析] 遵循IEEE 802.3ae标准的万兆以太网(10Gbps Ethernet)的帧格式和传统以太网 (10Mbps Ethernet)、快速以太网(100Mbps Ethernet)、千兆以太网(1Gbps Ethernet)的帧格式完全相同,它还保留了IEEE 802.3标准对Ethernet最小帧长度和最大帧长度的规定。由于数据传输速率高达10Gbps,传输介质只使用光纤;只以全双工方式工作,不存在信道争用问题,无须使用CSMA/CD协议;只具有SDH某些特性,只有异步的以太网接口,并没有提供SONET/SDH的同步接口。
在10000Base-ER、10000Base-EW、10000Base-LR和10000Base-L4标准中,网络拓扑为星型结构,物理层采用1550nm或1310nm波长激光,在使用10am单模光纤作为传输介质时,光纤最大长度可达40 km。
在10000Base-SW和10000Base-SR标准中,网络拓扑为星型结构,物理层采用850nm波长激光,在-使用62.5um或50um多模光纤作为传输介质时,光纤最大长度分别为35m与300m。

阅读理解

Marie Claire Magazine is one of the top women’s health, beauty and  fashion magazines in the world It has over 14 million readers all over the world.Maire Magazine is published in 32 countries including France, the Untied States ,Australia, China, the United Kingdom, Russia ,Spain Italy and many other nations.

Marie Claire Magazine has stood by its motto"More than a Pretty Face" since Jean Prouvost created it in France in1937. It was soon released every Wednesday and was an immediate success. Unfortunately, because of World War n, it stopped printing in 1940. But it b began in  again in 1954 as a monthly publication(出版物)instead of a weekly one.

The magazine has provided women throughout the world with information on health ,struggles and life stories of women. The magazine also focuses on current affairs all women would be interested in .It also has a part that specifically answers readers' questions.

The magazine discusses all of the latest and hottest things in clothing and accessories(首饰).It also provides its readers with shopping information to help find the best deals for the latest fashions.

The cover of Marie Claire Magazine has been graced(使增光)by many famous faces ,Although it is aimed at women, it broke new ground in 2003. The US publication featured a  man一Tom Cruise on its cover for the first time.Marie Claire Magazine has continued to be a pioneer in the magazine industry.

小题1:When was Marie Claire Magazine created?

A. In 1937.

B. In 1940.

C. In 1954.

D. In 2003.小题2:Marie Claire Magazine includes sections on                .

①health   ②fashion     ③first aid          ④current affairs

⑤babies   ⑥shopping   ⑦women's life stories ⑧readers' questions

A.①②③④⑤⑥

B.②③④⑤⑥⑦

C.②③⑤⑥⑦⑧

D.①②④⑥⑦⑧小题3:According to the passage,Marie Claire Magazine________.

A.pays a lot of attention to readers's responses

B.has been a monthly magazine since 1937

C.often has Tom Cruise on its cover

D.changed its boss in 1954小题4:What do we know about Marie Claire Magazine?

A.It is a local European magazine.

B. It never refers to hot social problems.

C. It contains beautiful pictures and useful articles.

D. It has more readers than any other magazine of the same kind

单项选择题