IEEE802.11MAC层具有多种功能,其中分布式协调功能采用的是哪一协议,用于支

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问题:

IEEE802.11MAC层具有多种功能,其中分布式协调功能采用的是哪一协议,用于支持突发式通信( )。

A.CSMA/CA

B.CSMA/CB

C.CSMA/CD

D.CSMA/CF

考点:计算机等级考试网络工程师网络工程师综合题
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One day, Peter had a fight with one of his classmates. Then he went to his grandfather and told him his story     .“He is really bad,”the boy said,“and I      him.”
The grandfather said,“      me tell you a story. When I was a boy, I too, sometimes hated others for what they did.”
As Peter         carefully, the grandfather went on.“There are always two tigers inside my heart. One is        and kind. He gets on well       everything around him. But       is bad and unfriendly. Even the smallest thing will make him angry. He fights with everyone all the time, and for no reason. He can’t think carefully       he always hates others. It is difficult to live with these two tigers inside my heart. They both try to control(控制)me.”
Peter looked into his grandfather’s         and asked,“      tiger always controls you, Grandfather?”
The old man said slowly and seriously,“The one that I feed. I always feed the good and kind tiger, so I never hate others and seldom(很少)get angry now.”
小题1:
A.happilyB.friendlyC.hardlyD.angrily
小题2:
A.loveB.hateC.knowD.enjoy
小题3:
A.MakeB.HelpC.LetD.Ask
小题4:
A.sawB.feltC.talkedD.listened
小题5:
A.goodB.badC.lazyD.quiet
小题6:
A.atB.onC.withD.about
小题7:
A.otherB.othersC.anotherD.the other
小题8:
A.becauseB.thoughC.beforeD.but
小题9:
A.eyesB.earsC.nose D.mouth
小题10:
A.WhoB.WhichC.WhereD.When
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下列关于地面水污染源的简化要求,说法错误的是()。

A.根据污染源的具体情况,排放形式可简化为点源、线源、面源,排放规律可简化为连续恒定排放和非连续恒定排放

B.在地面水环境影响预测中,通常可以把排放规律简化为连续恒定排放

C.无组织排放可以简化成面源;从多个间距很近的排放口排水时,可以简化为点源

D.评价等级为三级时,海湾污染源简化与大湖(库)相同

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患者,男,72岁,因慢性阻塞性肺气肿住院治疗。今早9时起开始静脉输入5%葡萄糖溶液500ml,滴速为80滴/分。10时左右,当护士来巡房时,发现患者咳嗽、咳粉红色泡沫样痰,呼吸急促,大汗淋漓。

护士首先应做的事情是()。

A.立即通知医生

B.给患者吸氧

C.安慰患者

D.立即停止输液

E.协助患者取端坐位,两腿垂直

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宁夏平原自古被称作“塞上明珠”,“其地饶五谷,尤宜稻麦,所产大米,清朝居贡米之列……,岁无旱涝之虞”。读图回答22—23题。

小题1:宁夏平原生产“贡米”等优质农产品,最优越的自然条件是

A.夏季高温多雨,热量充足

B.内陆晴天多,昼夜温差大

C.黄河水质好,营养丰富

D.纬度较高,生长期较长小题2:宁夏平原“地饶五谷,岁无旱涝之虞”,主要原因是

A.地处贺兰山山麓,冰雪融水丰富

B.地处贺兰山迎风坡,夏季降水丰沛

C.自古有黄河流经,灌溉水源充足稳定

D.自古有长城贯穿,抗灾减灾设施齐全

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危险物资包装标志的作用是什么?

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