问题 填空题

在点对点网络中,分组从通信子网的源结点到达目的结点的路由是由______决定的。

答案

参考答案:路由选择算法

解析: 由于连接多台计算机之间的线路结构可能是复杂的,因此从源结点到目的结点可能存在多条路由。决定分组从通信子网的源结点到达目的结点的路由由路由选择算法决定。采用分组存储转发与路由选择是点对点式网络与广播式网络的重要区别之一。

单项选择题
阅读理解

Facebook users may feel socially successful in the web world but they are more likely to perform poorly in exams. The majority of students who use Facebook every day are doing badly compared with those who don’t. About 83% of British 16 to 24-year-old people are using social networking site such as Facebook and MySpace, to keep in touch with friends and organize their social activities.

“Our study shows people who spend more time on Facebook spend less time studying,” said Aryn Karpinski, a researcher. “Every generation has its distractions(娱乐), but I think Facebook is a unique phenomenon.” Karpinski and a colleague questioned 219 US undergraduates and graduates about their study and general Internet use, as well as their specific use of Facebook. They found 65% of Facebook users accessed their account daily, checking it several times to see if they had received new messages. The amount of time spent on Facebook at each log-in(登录) varied from just a few minutes to more than an hour.

Some UK students have already realized the potential danger. Daisy Jones, 21, an undergraduate, realized the time she was spending on Facebook was threatening her grades, urging her to deactivate(使无效) her account, “I was in the library and tried to write a 2,000-word essay when I realized my Facebook habit had got out of hand,” she said. “I couldn’t resist going online, when thinking about it. Before you know it , a couple of minutes have turned into a couple of hours and you haven’t written a word.”

Jones is among the few to have realized the risks. 79% of the users, however, believed the time they spent on the site had no impact on their work. The CEO of Facebook said, “There is also academic research that shows the benefits of services like Facebook. It’s in the hands of students to decide how to spend their time.”

小题1:What can we know from Paragraph 1?

A.All the students who don’t use Facebook do well in exams.

B.Social networking sites have both advantages and disadvantages.

C.Facebook is the main site for British people to keep in touch.

D.Most of British students use social networking sites daily.小题2:Facebook users check their account frequently to ____________.

A.spend less time on study

B.make sure new messages aren’t missed

C.practise specific use of Facebook

D.accumulate amount of time spent on Facebook.小题3:Why did Daisy Jones deactivate her account?

A.She was warned about the risk of using Facebook.

B.Spending much time on Facebook affected her study

C.She wanted to write a long article in the library.

D.There was something wrong with her eyes.小题4:What’s the best title of the passage ?

A.Facebook fans do worse in exams

B.Social networking sites and their fans

C.Facebook helps organize social activities

D.How to use social networking sites correctly.