The insurance policy does not cover damage to the goods caused by normal _____. A: wear and sear B: sear and tear C: wear and tear
The insurance policy does not cover damage to the goods caused by normal _____. A: wear and sear B: sear and tear C: wear and tear
2016年12月四级真题第三套段落匹配题SectionBDirections:Inthissection,youaregoingtoreadapassagewithtenstatementsattachedtoit.Eachstatementcontainsinformationgiveninoneoftheparagraphs.Identifytheparagraphfromwhichtheinformationisderived.Youmaychooseaparagraphmorethanonce.Eachparagraphismarkedwithaletter.AnswerthequestionsbymarkingthecorrespondingletteronAnswerSheet2.CanBurglarsJamYourWirelessSecuritySystem?A.Anyproductthatpromisestoprotectyourhomedeservescarefulexamination.Soitisn’tsurprisingthatyou’11findplentyofstrongopinionsaboutthepotentialvulnerabilitiesofpopularhome—securitysystems.B.Themostlikelytypeofburglary(人室盗窃)byfaristheunsophisticatedcrimeofopportunity,usuallyinvolvingabrokenwindoworsomeforcedentry.AccordingtotheFB1.crimesliketheseaccountedforroughlytwo.thirdsofallhouseholdburglariesintheUSin2013.Thewidemajorityoftherestwereillegal.unforcedentriesthatresultedfromsomethinglikeawindowbeingleftopen.TheoddsofacriminalusingtechnicalmeanstobypassasecuritysystemaresosmallthattheFBIdoesn’teventrackthosestatistics.C.Oneofthemaintheoreticalhome—securityconcernsiswhetherornotagivensystemisvulnerabletobeingblockedfromworkingaltogether.Withwiredsetups,thefearisthataburglar(人室盗贼)mightbeabletoshutyoursystemdownsimplybycuttingtherightcable.Withawirelesssetup.youstickbattery—poweredsensorsuparoundyourhomethatkeepaneyeonwindows。doors,motion,andmore.Iftheydetectsomethingwrongwhilethesystemisarmed.they’lltransmitawirelessaleftsignaltoabasestationthatwillthenraisethealarm.Thatapproachwilleliminatemostcord—cuttingconcerns--butwhatabouttheirwirelessequivalent,jamming?withthefightdevicetunedtothefightfrequency,what’stostopathieffromjammingyoursetupandblockingthatalertsignalfromeverreachingthebasestation?D.Jammingconcernsarenothingnew,andthey’renotuniquetosecuritysystems.Anydevicethat’sbuilttoreceiveawirelesssignalataspecificfrequencycanbeoverwhelmedbyastrongersignalcominginonthesamefrequency.Forcomparison.1et’ssayyouwantedto“jam”aconversationbetweentwopeople—allyou’dneedtodoisyellinthelistener’sear.E)Securitydevicesarerequiredtolistthefrequenciestheybroadcaston—matmeansthatapotentialthiefcanfindwhattheyneedtoknowwithminimalGoogling.Theywill.however.needtoknowwhatsystemthey’relookingfor.Ifyouhaveasigninyouryarddeclaringwhatsetupyouuse,that’dpointthemintherightdirection,thoughatthatpoint,we’retalkingaboutahighlytargeted,semi—sophisticatedattack,andnotthesortofforced—entryattackthatmakesupthemajorityofburglaries.It’seasiertofindandacquirejammingequipmentforsomefrequenciesthanitisforothers.F)Wirelesssecurityproviderswilloftentakestepstohelpcombatthethreatofjammingattacks.SimpliSafe,winnerofourEditors’Choicedistinction.utilizesaspecialsystemthat’scapableofseparatingincidentalRFinterferencefromtargetedjammingattacks.Whenthesystemthinksit’sbeingjammed,it’llnotifyyouviapushalert(推送警报).Fromthere,it’suptoyoutosoundthealarmmanually.G)SimpliSafewassingledoutinonerecentarticleonjamming,completewithavideoshowingtheentiresystembeingeffectivelybypassedwithhandheldjammingequipment.AftertakingappropriatemeasurestocontaintheRFinterferencetoourtestlab,wetestedtheattackoutforourselves,andwereabletoverifythatit’spossiblewiththerightequipment.However.wealsoverifiedthatSimpliSafe’santi-jammingsystemworks.Itcaughtusintheact,sentanalerttomysmartphone,andalsolistedourRFinterferenceonthesystem’seventlog.Theteambehindthearticleandvideoinquestionmakenomentionofthesystem,orwhetherornotitdetectedthem.H)Weliketheuniquenatureofthatsoftware.Itmeansthatathieflikelywouldn’tbeabletoGooglehowthesystemworks.thenfigureoutawayaroundit.Eveniftheycould,SimpliSafeclaimsthatitssystemisalwaysevolving,andthatitvariesslightlyfromsystemtosystem,whichmeanstherewouldn’tbeauniversalmagicformulaforcrackingit.Othersystemsalsoseemconfidentonthesubjectofjamming.TheteamatFrontpointaddressestheissueinablogonitssite,citingtheirownjamprotectionsoftwareandclaimingthattherearen’tanydocumentedcasesofasuccessfuljamattacksincethecompanybeganofferingwirelesssecuritysensorsinthel980s.I)Jammingattacksareabsolutelypossible.Assaidbefore.withthefightequipmentandtherightknow—how,it’spossibletojamanywirelesstransmission.Buthowprobableisitthatsomeonewillsuccessfullyjamtheirwayintoyourhomeandstealyourstuff?J)Let’simaginethatyouliveinasmallhomewithawirelesssecuritysetupthatoffersafunctionalanti—jammingsystem.First,athiefisgoingtoneedtotargetyourhome,specifically.Then,he’sgoingtoneedtoknowthetechnicaldetailsofyoursystemandacquirethespecificequipmentnecessaryforjammingyourspecificsetup.Presumably,youkeepyourdoorslockedatnightandwhileyou’reaway,sothethiefwillstillneedtobreakin.Thatmeansdefeatingthelocksomehow,orbreakingawindow.He’11needtobejammingyouatthispoint,asabrokenwindoworopeneddoorwouldnormallyreleasethealarm.S0,too,wouldthemotiondetectorsinyourhome,sothethiefwillneedtocontinuejammingoncehe’sinsideandsearchingforthingstosteal.However.he’11needtodosowithouttrippingtheanti-jammingsystem,thedetailsofwhichhealmostcertainlydoesnothaveaccessto.K)Attheendoftheday,thesekindsofsystemsareprimarilydesignedtoprotectagainstthesortofopportunisticsmash—and—grabattackthatmakesupthemajorityofburglaries.They’realsoonlyasinglelayerinwhatshouldideallybeamany—sidedapproachtosecuringyourhome,onethatincludescommonsensethingslikesoundlocksandproperexteriorlightingatnight.Nosystemisimpenetrable,andnonecanpromisetoeliminatetheworstcasecompletely.Everyoneofthemhasvulnerabilitiesthataknowledgeablethiefcouldtheoreticallyexploit.Agoodsystemisonethatkeepsthatworst—casesettingasimprobableaspossiblewhilealsoofferingstrongprotectionintheeventofaless-extraordinaryattack.--1.Itispossibleforburglarstomakejammingattackswiththenecessaryequipmentandskill.--2.Interferingwithawirelesssecuritysystemissimilartointerferingwithaconversation.--3.Aburglarhastocontinuouslyjamthewirelesssecuritydevicetoavoidtriggeringthealarm,bothinsideandoutsidethehouse.--4.SimpliSafeprovidesdevicesthatareabletodistinguishincidentalradiointerferencefromtargetedjammingattacks.--5.Onlyaverysmallproportionofburglariesarecommittedbytechnicalmeans.--6.ItisdifficulttocrackSimpliSafeasitssystemkeepschanging.--7.Wirelessdeviceswilltransmitsignalssoastoactivatethealarmoncesomethingwrongisdetected.--8.Differentmeasuresshouldbetakentoprotectone’shomefromburglaryinadditiontothewirelesssecuritysystem.--9.SimpliSafe’sdevicecansendawarningtothehouseowner’scellphone.--10.Burglarscaneasilygetasecuritydevice’sfrequencybyInternetsearch.
2016年12月四级真题第三套段落匹配题SectionBDirections:Inthissection,youaregoingtoreadapassagewithtenstatementsattachedtoit.Eachstatementcontainsinformationgiveninoneoftheparagraphs.Identifytheparagraphfromwhichtheinformationisderived.Youmaychooseaparagraphmorethanonce.Eachparagraphismarkedwithaletter.AnswerthequestionsbymarkingthecorrespondingletteronAnswerSheet2.CanBurglarsJamYourWirelessSecuritySystem?A.Anyproductthatpromisestoprotectyourhomedeservescarefulexamination.Soitisn’tsurprisingthatyou’11findplentyofstrongopinionsaboutthepotentialvulnerabilitiesofpopularhome—securitysystems.B.Themostlikelytypeofburglary(人室盗窃)byfaristheunsophisticatedcrimeofopportunity,usuallyinvolvingabrokenwindoworsomeforcedentry.AccordingtotheFB1.crimesliketheseaccountedforroughlytwo.thirdsofallhouseholdburglariesintheUSin2013.Thewidemajorityoftherestwereillegal.unforcedentriesthatresultedfromsomethinglikeawindowbeingleftopen.TheoddsofacriminalusingtechnicalmeanstobypassasecuritysystemaresosmallthattheFBIdoesn’teventrackthosestatistics.C.Oneofthemaintheoreticalhome—securityconcernsiswhetherornotagivensystemisvulnerabletobeingblockedfromworkingaltogether.Withwiredsetups,thefearisthataburglar(人室盗贼)mightbeabletoshutyoursystemdownsimplybycuttingtherightcable.Withawirelesssetup.youstickbattery—poweredsensorsuparoundyourhomethatkeepaneyeonwindows。doors,motion,andmore.Iftheydetectsomethingwrongwhilethesystemisarmed.they’lltransmitawirelessaleftsignaltoabasestationthatwillthenraisethealarm.Thatapproachwilleliminatemostcord—cuttingconcerns--butwhatabouttheirwirelessequivalent,jamming?withthefightdevicetunedtothefightfrequency,what’stostopathieffromjammingyoursetupandblockingthatalertsignalfromeverreachingthebasestation?D.Jammingconcernsarenothingnew,andthey’renotuniquetosecuritysystems.Anydevicethat’sbuilttoreceiveawirelesssignalataspecificfrequencycanbeoverwhelmedbyastrongersignalcominginonthesamefrequency.Forcomparison.1et’ssayyouwantedto“jam”aconversationbetweentwopeople—allyou’dneedtodoisyellinthelistener’sear.E)Securitydevicesarerequiredtolistthefrequenciestheybroadcaston—matmeansthatapotentialthiefcanfindwhattheyneedtoknowwithminimalGoogling.Theywill.however.needtoknowwhatsystemthey’relookingfor.Ifyouhaveasigninyouryarddeclaringwhatsetupyouuse,that’dpointthemintherightdirection,thoughatthatpoint,we’retalkingaboutahighlytargeted,semi—sophisticatedattack,andnotthesortofforced—entryattackthatmakesupthemajorityofburglaries.It’seasiertofindandacquirejammingequipmentforsomefrequenciesthanitisforothers.F)Wirelesssecurityproviderswilloftentakestepstohelpcombatthethreatofjammingattacks.SimpliSafe,winnerofourEditors’Choicedistinction.utilizesaspecialsystemthat’scapableofseparatingincidentalRFinterferencefromtargetedjammingattacks.Whenthesystemthinksit’sbeingjammed,it’llnotifyyouviapushalert(推送警报).Fromthere,it’suptoyoutosoundthealarmmanually.G)SimpliSafewassingledoutinonerecentarticleonjamming,completewithavideoshowingtheentiresystembeingeffectivelybypassedwithhandheldjammingequipment.AftertakingappropriatemeasurestocontaintheRFinterferencetoourtestlab,wetestedtheattackoutforourselves,andwereabletoverifythatit’spossiblewiththerightequipment.However.wealsoverifiedthatSimpliSafe’santi-jammingsystemworks.Itcaughtusintheact,sentanalerttomysmartphone,andalsolistedourRFinterferenceonthesystem’seventlog.Theteambehindthearticleandvideoinquestionmakenomentionofthesystem,orwhetherornotitdetectedthem.H)Weliketheuniquenatureofthatsoftware.Itmeansthatathieflikelywouldn’tbeabletoGooglehowthesystemworks.thenfigureoutawayaroundit.Eveniftheycould,SimpliSafeclaimsthatitssystemisalwaysevolving,andthatitvariesslightlyfromsystemtosystem,whichmeanstherewouldn’tbeauniversalmagicformulaforcrackingit.Othersystemsalsoseemconfidentonthesubjectofjamming.TheteamatFrontpointaddressestheissueinablogonitssite,citingtheirownjamprotectionsoftwareandclaimingthattherearen’tanydocumentedcasesofasuccessfuljamattacksincethecompanybeganofferingwirelesssecuritysensorsinthel980s.I)Jammingattacksareabsolutelypossible.Assaidbefore.withthefightequipmentandtherightknow—how,it’spossibletojamanywirelesstransmission.Buthowprobableisitthatsomeonewillsuccessfullyjamtheirwayintoyourhomeandstealyourstuff?J)Let’simaginethatyouliveinasmallhomewithawirelesssecuritysetupthatoffersafunctionalanti—jammingsystem.First,athiefisgoingtoneedtotargetyourhome,specifically.Then,he’sgoingtoneedtoknowthetechnicaldetailsofyoursystemandacquirethespecificequipmentnecessaryforjammingyourspecificsetup.Presumably,youkeepyourdoorslockedatnightandwhileyou’reaway,sothethiefwillstillneedtobreakin.Thatmeansdefeatingthelocksomehow,orbreakingawindow.He’11needtobejammingyouatthispoint,asabrokenwindoworopeneddoorwouldnormallyreleasethealarm.S0,too,wouldthemotiondetectorsinyourhome,sothethiefwillneedtocontinuejammingoncehe’sinsideandsearchingforthingstosteal.However.he’11needtodosowithouttrippingtheanti-jammingsystem,thedetailsofwhichhealmostcertainlydoesnothaveaccessto.K)Attheendoftheday,thesekindsofsystemsareprimarilydesignedtoprotectagainstthesortofopportunisticsmash—and—grabattackthatmakesupthemajorityofburglaries.They’realsoonlyasinglelayerinwhatshouldideallybeamany—sidedapproachtosecuringyourhome,onethatincludescommonsensethingslikesoundlocksandproperexteriorlightingatnight.Nosystemisimpenetrable,andnonecanpromisetoeliminatetheworstcasecompletely.Everyoneofthemhasvulnerabilitiesthataknowledgeablethiefcouldtheoreticallyexploit.Agoodsystemisonethatkeepsthatworst—casesettingasimprobableaspossiblewhilealsoofferingstrongprotectionintheeventofaless-extraordinaryattack.--1.Itispossibleforburglarstomakejammingattackswiththenecessaryequipmentandskill.--2.Interferingwithawirelesssecuritysystemissimilartointerferingwithaconversation.--3.Aburglarhastocontinuouslyjamthewirelesssecuritydevicetoavoidtriggeringthealarm,bothinsideandoutsidethehouse.--4.SimpliSafeprovidesdevicesthatareabletodistinguishincidentalradiointerferencefromtargetedjammingattacks.--5.Onlyaverysmallproportionofburglariesarecommittedbytechnicalmeans.--6.ItisdifficulttocrackSimpliSafeasitssystemkeepschanging.--7.Wirelessdeviceswilltransmitsignalssoastoactivatethealarmoncesomethingwrongisdetected.--8.Differentmeasuresshouldbetakentoprotectone’shomefromburglaryinadditiontothewirelesssecuritysystem.--9.SimpliSafe’sdevicecansendawarningtothehouseowner’scellphone.--10.Burglarscaneasilygetasecuritydevice’sfrequencybyInternetsearch.
氢原子轨道的能级高低是 A: E(1s)<E(2s)<E(2p)<E(3s)<E(3p)<E(3d)<E(4s) B: E(1s)<E(2s)<E(2p)<E(3s)<E(3p)<E(4s)<E(3d) C: E(1s)<E(2s)=E(2p)<E(3s)=E(3p)<E(4s)<E(3d) D: E(1s)<E(2s)=E(2p)<E(3s)=E(3p)=E(3d)<E(4s)
氢原子轨道的能级高低是 A: E(1s)<E(2s)<E(2p)<E(3s)<E(3p)<E(3d)<E(4s) B: E(1s)<E(2s)<E(2p)<E(3s)<E(3p)<E(4s)<E(3d) C: E(1s)<E(2s)=E(2p)<E(3s)=E(3p)<E(4s)<E(3d) D: E(1s)<E(2s)=E(2p)<E(3s)=E(3p)=E(3d)<E(4s)
E→ E + E | E - E | E * E | E / E | ( E ) | i 下面的推导过程是句子i+i*i的规范推导的是: E=>E*E=>E*i=>E+E*i=>E+i*i=>i+i*i|E=>E*E=>E*i=>E+E*i=>i+E*i=>i+i*i|E=>E+E=>E+E*E=>E+E*i=>E+i*i=>i+i*i|E=>E+E=>E+E*E=>E+i*E=>E+i*i=>i+i*i
E→ E + E | E - E | E * E | E / E | ( E ) | i 下面的推导过程是句子i+i*i的规范推导的是: E=>E*E=>E*i=>E+E*i=>E+i*i=>i+i*i|E=>E*E=>E*i=>E+E*i=>i+E*i=>i+i*i|E=>E+E=>E+E*E=>E+E*i=>E+i*i=>i+i*i|E=>E+E=>E+E*E=>E+i*E=>E+i*i=>i+i*i
下列情况中，属于饱和状态的是（ ）。 A: E≠e B: E＞e C: E=e D: E＜e
下列情况中，属于饱和状态的是（ ）。 A: E≠e B: E＞e C: E=e D: E＜e
一维、二维、三维k空间中，能级密度Z(E)与能量E之间的关系分别对应满足( ) A: Z(E)=常数、Z(E)∝√E、Z(E)∝１／√E B: Z(E)∝√E、Z(E)=常数、Z(E)∝１／√E C: Z(E)∝√E、Z(E)∝１／√E、Z(E)=常数 D: Z(E)∝１／√Z(E)=常数、Z(E) ∝√E
一维、二维、三维k空间中，能级密度Z(E)与能量E之间的关系分别对应满足( ) A: Z(E)=常数、Z(E)∝√E、Z(E)∝１／√E B: Z(E)∝√E、Z(E)=常数、Z(E)∝１／√E C: Z(E)∝√E、Z(E)∝１／√E、Z(E)=常数 D: Z(E)∝１／√Z(E)=常数、Z(E) ∝√E
掺铒光纤放大器（EDFA）中Er A: E吸收＞E激发＋E自发 B: E自发＞E吸收＋E激发 C: E激发＞E自发＋E吸收 D: E自发＜E吸收＋E激发
掺铒光纤放大器（EDFA）中Er A: E吸收＞E激发＋E自发 B: E自发＞E吸收＋E激发 C: E激发＞E自发＋E吸收 D: E自发＜E吸收＋E激发
下列关于停留时间分布密度函数的描述，正确的是 。 A、E（φ）=E（τ） B、E（φ）=τE（τ） C、E（τ）=τE（φ） D、以上均不正确 A: E（φ）=τE（τ） B: E（φ）=E（τ） C: E（τ）=τE（φ） D: 以上均不正确
下列关于停留时间分布密度函数的描述，正确的是 。 A、E（φ）=E（τ） B、E（φ）=τE（τ） C、E（τ）=τE（φ） D、以上均不正确 A: E（φ）=τE（τ） B: E（φ）=E（τ） C: E（τ）=τE（φ） D: 以上均不正确
语句while（!e）；中条件!e等价于（ ）。A:e==0 B:e!=1 C:e!=0 D:-e A: e==0 B: e!=1 C: e!=0 D: -e
语句while（!e）；中条件!e等价于（ ）。A:e==0 B:e!=1 C:e!=0 D:-e A: e==0 B: e!=1 C: e!=0 D: -e
以下哪个文法存在二义性（ ） A: E → E+T | TT → T*F | FF → (E) | i B: S → aSaS → bSbS → ε C: E → E + E E → E * E E → ( E ) E → i D: S → aSS → bSS → ε
以下哪个文法存在二义性（ ） A: E → E+T | TT → T*F | FF → (E) | i B: S → aSaS → bSbS → ε C: E → E + E E → E * E E → ( E ) E → i D: S → aSS → bSS → ε