问题 单项选择题

万维网(World Wide Web,WWW)信息服务是Internet上的一种最主要的服务形式,它进行工作的方式是基于______。

A.单机

B.浏览器/服务器

C.对称多处理器

D.客户/服务器

答案

参考答案:B

解析: 随着网络技术的发展,万维网(World Wide Web,WWW)信息服务已经迅速成为Internet上的一种最主要的服务形式,它采用客户/服务器模式进行工作。WWW服务器负责存放和管理大量的网页文件信息,并负责监听和查看是否有从客户端传过来的连接。

判断题
问答题

Going to the ballpark, visiting friends and playing bingo are simple diversions for many of us. But for the elderly, these social pastimes may play a critical role in preserving their physical and mental health.

(46) In fact, a new study suggests that the less time older people spend engaged in social activity, the faster their motor function tends to decline. "Everybody in their 60s, 70s and 80s is walking more slowly than they did when they were 25," says Dr. Aron Buchman, a neurologist at the Rush University Medical Center in Chicago and leading author of the study, which was published in the June 22nd issue of the Archives of Internal Medicine. (47) "Our study shows the connection between social activity and motor function--and opens up a whole new universe of how we might intervene. "

(48) An increasing body of evidence has suggested that participating in mentally stimulating activity, socializing frequently and exercising may help protect against age-related decline-at least cognitive decline. As early as 1995, neuroscientist Carl Cotman, who studies aging and dementia at the University of California at Irvine, published a paper in Nature showing that physical exercise produces a protein that helps keep neurons from dying and spurs the formation of new neural connections in the brain. (49) More recently, Cotman demonstrated in studies of elderly dogs and mice that enriching their social environment is associated with improvement in brain function.

Researchers are also finding that social activity may be linked to the same protective effect in people. A recent study of 2 500 adults ages 70 to 79, published in the journal Neurology, found that those who were able to stay mentally sharp were also those who exercised once a week or more, had at least a ninth grade literacy level and were socially active.

While further research needs to be done to establish the exact impact of social activity and exercise on specific age-related declines (50) it’s likely that a reduction in social activity may simply be a symptom of physical decline, since people may naturally withdraw from social engagement as they lose motor skills-most researchers would agree that it is not unreasonable to encourage seniors to get out there more. Only 10% of people over 65 get the recommended amount of exercise (at least 2. 5 to 5 hours a week), and given that seniors already tend to be more socially isolated than younger adults, it’s difficult to motivate them to become more active. "If you are alone, you are less likely to follow recommendations," notes Verghese. It might help, though, if you visit Grandma more often and let her know that a regular pastime may just help her stay fitter and sharper longer.

(47) "Our study shows the connection between social activity and motor function--and opens up a whole new universe of how we might intervene. "