未分类题

TCP/IP是一个协议族,它的体系结构分4层:应用层、网际层、网络接口层和(46),其中ARP协议属于(47)。为了在源主机和目的主机之间传送数据,IP协议需要确定源主机和目的主机是否在同一个网络中。

A.会话层
B.传输层
C.网络层
D.表示层

【参考答案】

它的体系结构分4层:应用层、网际层、网络接口层和传输层
其中ARP协议属于网络层
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There is extraordinary exposure in the United States to the risks of injury and death from motor vehicle accidents. More than 80 percent of all households own passenger cars or light trucks and each of these is driven an average of more than 11,000 miles each year. Almost one-half of fatally injured drivers have a blood alcohol concentration (BAC) of 0.1 percent or higher. For the average adult, over five ounces of 80 proof spirits would have to be consumed over a short period of time to attain these levels. One third of drivers who have been drinking, but fewer than 4 percent of all drivers, demonstrate these levels. Although less than 1 percent of drives with BACs of 0.1 percent or more are involved in fatal crashed, the probability of their involvements is 27 times higher than for those without alcohol in their blooD.There are a number of different approaches to reducing injuries in which drinking plays a rolE.Based on the observation that excessive consumption correlates with the total alcohol consumption of the country's population, it has been suggested that higher taxes on alcohol would reduce both. While the heaviest drinkers would be taxed the most, anyone who drinks at all would be punished by this approach.To make drinking and driving a criminal offense is an approach directed only at drinking drivers. In some states, the law empowers police to request breath tests of drivers committing any traffic offense and higher BAC can be basis for arrest. The National Highway Traffic Safety Administration estimates, however, that even with increased arrests, there are about 700 violations for every arrest. At this level there is little evidence that laws are effective ways to reduce drunk driving. In Britain, motor vehicle accidents fell 25 percent immediately following implementation of he Road Safety Act in 1967. As Britishers increasingly recognized that they could drink and not be stopped, the effectiveness declined, although in the following three years the death-rate seldom reached that observed in the seven years prior to the Act.Whether penalties for driving with a high BAC or excessive taxation on consumption of alcoholic drink will deter the excessive drinker responsible for most accidents is unclear. One thing is clear, however, unless we deal with automobile and highway safety and reduce accidents in which alcoholic drinking plays a role, many will continue to diE.The author is primarily concerned with______A.interpreting the results of surveys on traffic accidentsB.reviewing the effectiveness of attempts to reduce drank drivingC.analyzing the causes of the large number of annual traffic deathsD.making an international comparison of experience with drank driving
A.1
B.1
C.
D.
E.
The
F.interpreting
G.reviewing
H.analyzing
I.making
未分类题
Generally speaking, a British is widely regarded as a quiet, shy and conservative person who is 【21】______ only among those with whom he is acquainteD.When a stranger is at present, he often seems nervous, 【22】______ embarrasseD.You have to take a commuter train any morning or evening to 【23】______ the truth of this. Serious-looking businessmen and women sit reading their newspapers or dozing in a comer; hardly anybody talks, since to do so would be considered quite offensivE.【24】______ , there is an unwritten but clearly understood code of behavior. which, 【25】______ broken, makes the offender immediately the object of 【26】______ .It has been known as a fact that a British has a 【27】______ for the discussion of their weather and that, if given a chance, he will talk about it 【28】______ . Some people argue that it is because the British weather seldom 【29】______ forecast and hence becomes a source of interest and 【30】______ to everyonE.This may be so. 【31】______ a British cannot have much 【32】______ in the weathermen, who, alter promising fine, sunny weather for the following day, are often proved wrong 【33】______ a cloud over the Atlantic brings rainy weather to all districts! The man in the street seems to be as accurate -- or as inaccurate -- as the weathermen in his 【34】______ .Foreigners may be surprised at the number of references 【35】______ weather that the British make to each other in the course of a single day. Very often conversational greetings are 【36】______ by comments on the weather. 'Nice day, isn't it?' 'Beautiful day!' may well be heard instead of 'Good morning, how are you?' 【37】______ the foreigner may consider this exaggerated and comic, it is worthwhile pointing out that it could be used to his advantagE.【38】______ he wants to start a conversation with a British but is 【39】______ to know where to begin, he could do well to mention the state of the weather. It is a sale subject which will 【40】______ an answer from even the most reserved of the British.【21】A.relaxedB.frustratedC.amusedD.exhausted
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C.
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【21】
A.relaxed
B.frustrated
C.amused