第51題： 某簡(jiǎn)單無向連通圖G的頂點(diǎn)數(shù)為n，則圖G最少和最多分別有（  ）條邊。
A.n,n2/2
B.n-1,n*(n-1)/2
C.n,n*(n-1)/2
D.n-1,n2/2
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第52題： 根據(jù)漸進(jìn)分析，表達(dá)式序列：n4, lgn, 2n, 1000n, n2/3, n!從低到高排序?yàn)椋?nbsp; ）。
A.Ign,1000n, n2/3, n4, n!, 2n
B.n2/3,1000n, lgn, n4, n!, 2n
C.lgn,1000n, n2/3, 2n, n4, n!
D.Ign, n2/3, 1000n, n4, 2n, n!
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第53題： 采用DHCP動(dòng)態(tài)分配IP地址，如果某主機(jī)開機(jī)后沒有得到DHCP服務(wù)器的響應(yīng)。則該主機(jī)獲取的IP地址屬于網(wǎng)絡(luò)（  ）。
A.202.117.0.0/24
B.192.168.1.0/24
C.172.16.0.0/16
D.169.254.0.0/16
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第55題： 當(dāng)修改郵件時(shí)，客戶與POP3服務(wù)器之間通過（  ）建立連接，所使用的端口是（  ）。
1)A.HTTP
B.TCP
C.UDP
D.HTTPS
2)A.52
B.25
C.1100
D.110
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第56題： 因特網(wǎng)中的域名系統(tǒng)(Domain Name System)是一個(gè)分層的域名，在根域下面是頂級(jí)域，以下頂級(jí)域中，（  ）屬于國(guó)家頂級(jí)域。
A.NET
B.EDU
C.COM
D.UK
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第57題： Regardless of how wellDesigned,Constructed,And testedA system orApplication mayBe, errors orBugs will inevitably occur. OnceA system hasBeen（  ），it enters operationsAnd support.
Systems support is the ongoing technical support for user,As wellAs the maintenance required to fixAny errors, omissions,or new requirements that mayArise.BeforeAn information systemCanBe（  ）, it mustBe in operation. System operation is theDay-to-day, week-to-week, month-to-month,And year-t-year（  ）ofAn information system'sBusiness processesAndApplication programs.
Unlike systemsAnalysis,Design,And implementation, systems supportCannot sensiblyBe（  ）intoActual phases thatA support project must perform. Rather, systems supportConsists of four ongoingActivities thatAre program maintenance, system recovery, technical support,And system enhancement.EachActivity isA type of support project that is（  ）byA particular problem,event, or opportunity encountered with the implemented system.
1)A.designed
B.implemented
C.investigated
D.analyzed
2)A.supported
B.tested
C.implemented
D.constructed
3)A.construction
B.maintenance
C.execution
D.implementation
4)A.broke
B.formed
C.composed
D.decomposed
5)A.triggered
B.leaded
C.caused
D.produced
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