搜题请搜索小程序“爱下问搜题”
问题 单项选择题 共用题干题

When the system upon which a transport entity is running fails and subsequently restarts,the(21) information of all active connections is lost. The affected connections become half-open, as the side that did not fail does not yet realize the problem.The still active side of a half-open connections can close the connection using a(22)timer. This timer measures the time the transport machine will continue to await an (23) of a transmitted segment after the segment has been retransmitted the maximum number of times.When the timer (24),the transport entity assumes that either the other transport entity or the intervening network has failed. As a result, the timer closes the connection, and signals an abnormal close to the TS user. In the event that a transport entity fails and quickly restarts, half-open connections can be terminated more quickly by the use of the RST segment, the failed side returns an RST i to every segment i that it receives. When the RST i reaches the other side, it must be checked for validity based on the (25) number i, as the RST could be in response to an old segment. If the reset is valid, the transport entity performs an abnormal termination.

空白处（24）应选择（）

A.stops

B.restarts

C.expires

D.abandons

答案

参考答案：C

解析：分析当传输实体发送失败，系统随后重新启动时，所有活动连接的状态信息都会丢失。受影响的连接则变成半开放的，没有失败的一端并不知道另一端发生的问题。半开放连接中活动的一端可以使用“放弃”计时器来关闭连接。当传输机器把一个包重新发送最大次数后，将持续等待传输包的回应，这时计时器就计算时间。当时间终了时，传输实体就假设另一个端的传输实体或中间的网络失败。因而，计时器关闭连接，且给TS用户发送一个异常关闭的信号。在一个传输实体失败并立即重新开始的事件中，可以使用RST包更快地结束半开放的连接。失败的一端返回一个RST（i）给它收到的每一个包i。当这个RST到达另一端时，必须进行基于序号i的有效性检查，就像这个RST响应原来的包一样。如果重置无效，则传输实体异常终止。

单项选择题

《本草纲目》记载的药味数是（）

A.850种

B.1892种

C.365种

D.1742种

E.730种
查看答案
完形填空

根据首字母提示完成短文, 每空一词。

Learning to save money when you’re young is an i_______小题1:lesson. All good habits should begin early, and saving is a skill that everyone needs. But many people do not have a good sense of s______小题2:for the long run. 　　

I have been lucky to learn this lesson early because I have had a grass-cutting business s____小题3:I was 10 years old. Of the money I make I spend about 10 p_______小题4:and save the other 90%. 　　

Making sure you save and don’t spend too much is a good way to build up wealth (财富). I have put my earnings in a bank. However, many teens I know usually s_______小题5:all the money they earn, so it never has a chance to grow. Young people should r______小题6:that their teenage years are a great time to begin saving. 　　

At high school your parents will p_______小题7:for almost everything you need, so your expenses (消费) can be small. If you have a job, you should have fun with some of the money. But you should also save some so that it will grow. Then you can begin planning for your f_______小题8:. When you spend money, you not only lose that money, but also lose the interest you could have earned by saving it. 　　

After high school, college is expensive and then “real” life begins, with expenses such as food and rent. If you can hold onto a good percentage of the money you earn as a teen, going to college and buying a new h_______小题9:of your own will be much easier. If you are in your teen without any savings, you will always have to struggle. The e_______小题10:you begin saving, the easier it is to create a nest egg.

查看答案