问题 单项选择题

以太网策略中有3种监听方法,其中一种是,一旦“介质空闲就发送数据,假如介质忙,继续监听,直到介质空闲后立即发送数据”,这种算法称为 (31) 监听算法。这种算法的主要特点是 (32) 。 CSMA/CD协议具有:中突检测功能,网络中的站点一旦检测到>中突,就立即停止发送,并发阻塞码,其他站点都会 (33) 。如果基带总线的段长为d=1000m,中间没有中继器,数据速率为R=10Mbit/s,信号传播速率为V=200m/μs,为了保证在发送期间能够检测到冲突,则该网络上的最小帧长为 (34) bit。对于具有同样参数的宽带总线网络,最小帧长应为 (35) bit。

A.坚持型

B.非坚持型

C.P-坚持型

D.0-持型

答案

参考答案:A

解析:以太网策略中有3种监听方法,其中—种是,一旦“介质空闲就发送数据,假如介质忙,继续监听,直到介质空闲后立即发送数据”,这种算法称坚持型。这种算法在网络空闲时减少了发送时延,从而提高了介质利用率,但是会在同时监听的站之间引起>中突,所以网络在繁忙时可能会降低介质利用率。答案为A。

单项选择题 B1型题
完形填空
When my son was first diagnosed with autism (孤独症), it was a very hard time for us.In some ways it was a  16_ because we finally knew the name.of the disease after visiting many hospitals, but it also  17__ years bf uncertainty, and we didn't know what  18_was like.
When I  19__the news with my coworkers, I was so surprised but happy to receive so much immediate   20  from them .They were focused on what we_21___, not how it would affect my ability to work.
One coworker in particular was  22__, She was always kind and considerate; She called me into her  23__ a few days later, and gave me a(n) "  24__stone''.It is a small stone with an indention (凹陷)for your  25__, It gives you something to  26__ when you're worried . rubbing your thumb around on this stone.It was a lovely 27__.It turned out to be an effective way to reduce anxiety.
She then made a permanent offer to 28_ us to any appointment or testing we needed. Considering the fact that we_ 29__ 90 minutes from where most.treatments took place, this was a(n)  30_offer.She made it very clear to me that this offer  31_last-minute trips or emergencies.Anytime we needed to go anywhere , She was willing to be our transportation.
We never did need to bother her,   32__ knowing it was there and that she was so willing to 33__ made it feel like we were much less _34  
I'm very grateful to her and.  35__ around us who came together to be a support system in our time of need.We were really moved by the level of support we received.
小题1:
A.surpriseB.reliefC.pleasure D.success .
小题2:
A.meantB.brokeC.endedD.explained
小题3:
A.a dreamB.4 planC.the futureD.the job
小题4:
A.receivedB.doubtedC.heardD.shared
小题5:A.treatment         B.love            C, complaints           D.gifts
小题6:
A.neededB.sawC.failedD.learned
小题7:
A.rudeB.gratefulC.amazingD.cold
小题8:
A.officeB.school.C.gardenD.restaurant
小题9:
A.-fearB.peaceC.angerD.worry
小题10:
A.ringB.thumbC.luckD.courage
小题11:
A.focus onB.believe inC.care aboutD.know about
小题12:
A.languageB.expressionC.gesture D.message
小题13:
A.devoteB.attachC.introduceD.drive
小题14:
A.ranB.livedC.walkedD.rode
小题15:
A.finalB.firmC.greatD.unconditional
小题16:
A.refusedB.welcomedC.passedD.included
小题17:
A.butB.LC.because D.if
小题18:A, move            B.wait               C.help          D.pay
小题19:
A.importantB.aloneC.awakeD.busy
小题20:
A.bothB.fewC.nobodyD.everyone