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已知边长为的空间四边形ABCD的顶点都在同一个球面上，若，二面角A﹣BD﹣C的余弦值为，则该球的体积为 ．
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高三下学期数学《》真题及答案
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若一个四边形的一条对角线把四边形分成两个等腰三角形我们把这条对角线叫这个四边形的和谐线这个四边形叫做
下列说法不正确的是
空间中，一组对边平行且相等的四边形是一定是平行四边形；
同一平面的两条垂线一定共面；
过直线上一点可以作无数条直线与这条直线垂直，且这些直线都在同一个平面内；
过一条直线有且只有一个平面与已知平面垂直.
邻边不相等的平行四边形纸片剪去一个菱形余下一个四边形称为第一次操作在余下的四边形纸片中再剪去一个菱形
邻边不相等的平行四边形纸片剪去一个菱形余下一个四边形称为第一次操作在余下的四边形纸片中再剪去一个菱形
一个六棱柱的底面是正六边形其侧棱垂直底面已知该六棱柱的顶点都在同一个球面上且该六棱柱的高为底面周长为
在四边形ABCD中已知AD∥BC.若再添加一个条件能使四边形ABCD成为平行四边形则这个条件可以是写
邻边不相等的平行四边形纸片剪去一个菱形余下一个四边形称为第一次操作在余下的四边形纸片中再剪去一个菱形
四边形ABCD中已知AB＝CD若再增加一个条件只填写一个可得四边形ABCD是平行四边形.
已知各顶点都在同一个球面上的正四棱柱的高为4体积为16则这个球的表面积是..
如图四棱锥P﹣ABCD中PA⊥平面ABCD四边形ABCD为正方形PA=AB=2四棱锥P﹣ABCD的
下列说法不正确的是
空间中，一组对边平行且相等的四边形是一定是平行四边形；
同一平面的两条垂线一定共面；
过直线上一点可以作无数条直线与这条直线垂直，且这些直线都在同一个平面内；
过一条直线有且只有一个平面与已知平面垂直.
如图3×3网格中一个四边形ABCD若小方格正方形的边长为1则四边形ABCD的周长是______
下列四边形中四个顶点一定在同一个圆上的是
平行四边形
菱形
矩形
直角梯形
已知各顶点都在同一个球面上的正四棱锥高为3体积为6则这个球的表面积是_____.
邻边不相等的平行四边形纸片剪去一个菱形余下一个四边形称为第一次操作在余下的四边形纸片中再剪去一个菱形
如图在5×5的方格纸中每一个小正方形的边长都为1.四边形ABCD的顶点都在格点上.1∠BCD是不是直
邻边不相等的平行四边形纸片剪去一个菱形余下一个四边形称为第一次操作在余下的四边形纸片中再剪去一个菱形
一个空间四边形ABCD的四条边及对角线AC的长均为二面角D﹣AC﹣B的余弦值为则下列论断正确的是
空间四边形ABCD的四个顶点在同一球面上且此球的表面积为3π
空间四边形ABCD的四个顶点在同一球面上且此球的表面积为4π
空间四边形ABCD的四个顶点在同一球上且此球的表面积为
不存在这样的球使得空间四边形ABCD的四个顶点在此球面上
邻边不相等的平行四边形纸片剪去一个菱形余下一个四边形称为第一次操作在余下的四边形纸片中再剪去一个菱形
如图在同一个平面内四边形ABCD可以变化到四边形ABEF的位置关于这个过程下列叙述正确的是
四边形ABCD变化为四边形ABEF是图形的平移
四边形ABCD变化为四边形ABEF图形的旋转
点
运动到F.，这个过程是平移D.点D.运动到F.，这个过程是旋转
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图中能正确表示基因分离定律实质的是
Althoughtheideaofzeroemissionnetcarbon﹣positivesustainable可持续developmentwaspromotedworldwidemostcitiesareatalosswhattodoorevensomehaveobjectedtoit.ButinLiuzhouacityinsouthernChinaattitudescouldnotbemoredifferent. TheLiuzhouMunicipalityUrbanPlanningBureauhassignedupItalianarchitectStefanoBoerithefatheroftheforestcitymovementtobuildaself﹣containedcommunityforupto30000people.Heisthego﹣tomanforsuchprojectsthankstothesuccessofhisverticalforeststworesidential住宅的towers.Completedin2014theyremoveupto17.5tonsofsoot煤烟fromtheaireachyearandayearlateroneofthemwasnamedBestTallBuildingWorldwide. TheLiuzhouprojectisamuchmoreambitiousundertakinghowever.Itshomeshospitalshotelsschoolsandofficeswillbebuiltona340﹣acresiteinwhatBoericallsthefirstattempttocreateanurbanenvironmentthatisreallytryingtofindabalancewithnature.Its100speciesofplantlifeareexpectedtoabsorbalmost10000tonsofcarbondioxideand57tonsofpollutantsperyearwhileatthesametimeproducing900tonsoflife﹣givingoxygen. Althoughthearchitectshaven'tpublishedthecostoftheforestcitytheMilantowerscostonlyfivepercentmorethantraditionalskyscrapers. TheconstructionofhisforestcityatLiuzhouissettobeginin2020andthereisstillagreatdealofplanningandresearchrequiredbeforeaprojectedcompletiondatecanbeset.HoweverBoeriremainsoptimisticabouttheprojectandhasconfidenceinthesoundnessofhisvisionIreallythinkthatbringingforestsintothecityisawaytodealwithglobalwarming. 1What'sLiuzhou'sattitudetowardsthesustainabledevelopment? A.Approving. B.Cautious. C.Unfavorable. D.Doubtful. 2WhyisStefanoemployedfortheLiuZhouproject? A.Hevolunteeredtodotheproject. B.Heisafamousarchitectintheworld. C.Heisthefatheroftheforestrecovery. D.Hehasgainedexperienceinsimilarprojects. 3Whatdoestheunderlinedwordtheyreferto? A.Thearchitects. B.Thetwotowers. C.Forestsinthecity. D.Theresidentsofthecity. 4What'sthepurposeofLiuZhouproject? A.Toprovidemorejobs. B.Tobringforestintocity. C.Tosolvehouseshortage. D.Toimprovetheenvironment.
酵母菌进行有氧呼吸和无氧呼吸的共同终产物是
Asafirstresponderyouneverknowwhattypeofsituationyoumightwalkintoorwhoyou'llmeetalongtheway.That'sdefinitelybeenthecaseforJeffreyLanenberga51﹣year﹣oldparamedic急救医务人员since1984. TenyearsintothejobLanenbergreceivedacallthatreportedthatamaninhisearly30shadfallendownintheMallofAmerica.WhenLanenbergandhispartnerarrivedatthescenetheyfoundtheyoungmalefacedownontheground.Hehadgoneunconsciousmakingweakattemptstobreathe.Hiswifestoodbesidehimholdingtheirsmallsoninhorror.Theyquicklyrushedtodefibrillate除颤andcalmthemantokeephimundercontrol.AfterLanenbergdroppedthepatientoffattheneighboringhospitalhethoughtaboutthemanandhisfamilyforalongtime. LanenbergthoughthehadexperiencedeverythingunderthesununtilonerandomvisittoOfficeMaxthreeyearsagowherehemetamanrepeatedlywalkbackandforthwhilestaringathim.Asitturnedoutthemanwasthepatienthehadsaved20yearsearlier. Yougaveme20yearsmorethanIeverthoughtI'dhavethemansaid.HethankedLanenbergrepeatedlyandtoldhimhehadsomeonehewantedhimtomeet.Hesteppedaroundthecornerandreappearedwitha20﹣something﹣year﹣oldman.Lanenberginstantlyknewthatitwasthesonhehadseenstandingbyhismotherallthoseyearsago. ThatdaychangedmylifeLanenbergsaid.Beforethateverythingwasaboutwork…WhenItalktomybeginner﹣trainingclassItellthemyouneverknowtheimpactyoucanhaveonsomeone'slife. 1WhatdidLanenbergdowiththeyoungman? A.Hegavethemanthefirstaid. B.Hecuredthemanatthescene. C.Heonlysentthemantohospital. D.Hetookcareoftheman'swifeandson. 2WhatdidLanenbergthinkoftheencounterwiththeman? A.Itwasunbelievable. B.Itwasacommonroutine. C.Itwasamatterofcourse. D.Itwasadangeroussituation. 3WhywasthemanthankfultoLanenberg? A.Lanenberghelpedbringuphislittleson. B.Lanenbergdonatedtosupporthisfamily. C.Lanenberggavehimthepresenthappylife. D.Lanenbergtaughthissontobeanewdoctor. 4HowdidthemeetingchangeLanenberg'slife? A.Hechangedhisattitudetohisjob. B.Hewasrewardedwithmuchmoney. C.Hegotapromotiontobeateamleader. D.Hetookupteachingworktotrainnewcomers.
LastweekVodafonestartedatestoftheUK'sfirstfull5GserviceavailableforusebybusinessesinSalford.ItispartofitsplantotrialthetechnologyinsevenUKcities.Butwhatcanweexpectfromthenextgenerationofmobiletechnology? Onethingwewillseeinthepreparationforthetestislotsoftrickswiththenewtech.Earlierthisyearoperatorspaidalmost£1.4billionforthe5Gwavelengthsandtocompensateforthatcashtheywillneedtocatchtheeyeofconsumers.InSeptemberVodafoneuseditsbitoftherangetodisplaytheUK'sfirsthologram全息call.TheManchesterCitycaptainStephHoughtonappearedasaholograminNewbury.Itisn'tallhologramshowever5Gwillofferfasterinternetaccess.withOfcom英国通讯管理局suggestingthatvideothattakesaminutetodownloadon4Gwillbeavailableinjustasecond. Thewiderapplicationistosupportconnectedequipmentontheinternetofthings﹣notjusttheinternet﹣enabledfridgethatcanreorderyourmilkforyoubutthenetworkthatwillenabledriverlesscarsanddeliverydrones无人机tocommunicatewitheachother. ProfWilliamWebbhaswarnedthatthetechnologycouldbeacaseoftheemperor'snewclothes.Muchofthespeedincreaseheclaimscouldhavebeenachievedbyputtingmoremoneyinthe4Gnetworkratherthananewtechnology.OtherdifferentvoiceshavesuggestedthatafocusonrollingoutwiderruralbroadbandaccessandaddressingcurrentnetworkcoveragewouldbemorebeneficialtotheUKasawhole. Obviously5Gwillalsobringacosttoconsumers.Itrequiresahandsetforboth5Gand4Gandthefirst5G﹣enabledsmartphonesareexpectedinthecomingyear.Withtheslowpaceofnetworkrolloutsofaritislikelythatconsumerswillendupupgradingtoanew5Gphonewellbefore5Gbecomeswidelyavailableinthenextcoupleofyears. 1WhydoesProfWilliamWebbsaythetechnologycouldbeacaseoftheemperor'snewclothes? A.Heisinfavoroftheapplicationofthenewtechnology. B.5Gwillbringacosttoconsumersintheirdailylife. C.5Ghelpspeoplecommunicatebetterwitheachother. D.Heprefersmoremoneytobespenton4Gnetworks. 2Theunderlinedwordaddressinginthefourthparagraphhastheclosestmeaningto. A.makingaspeechto B.tryingtosolve C.managingtodecrease D.respondingto 3Thelastparagraphindicatesthat. A.it'lltakeseveralyearstomake5GaccessibletothepublicintheUK B.5Gserviceshowshugedevelopmentpotentialandabroadmarket C.customersareeagertouse5Gsmartphonesinsteadof4Gones D.it'sprobablethat5GnetworkrolloutisspeedingupinBritain 4Whatdoweknowaboutthetext? A.Vodafoneissuccessfulinspreadingthe5Gservice. B.StephHoughtonappearedasahologramby4G. C.Theapplicationof5Gwillmakelifemucheasier. D.5GphonesareavailableinruralareasoftheUK.
如图所示的电路中电源电压保持不变R2＝20Ω闭合开关S移动滑动变阻器R2的滑片到中点c时电流表的示数为0.4A移动滑片P到最左端a时电流表的示数为0.3A求电源电压和R1的阻值．
下列关于细胞分裂分化衰老和凋亡的叙述中正确的是
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下列各项应用中主要是利用细胞呼吸原理的是 ①手指受伤时选择透气的消毒纱布包扎 ②稻田定期排水有利根的生长 ③利用葡萄粮食和酵母菌制酒 ④大棚种植用无色透明薄膜
下面是光合作用过程示意图请回答问题． 1光合作用包括两个阶段其中E是在叶绿体的进行该阶段需要D阶段提供的物质是． 2叶绿体的色素分布在．图中A是． 3光合作用发生的部位是． A．叶绿素B．叶绿体C．叶绿体的基粒D．叶绿体的基质
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September222018willbeWorldCar﹣FreeDayadayonwhichpeopleacrosstheglobeareencouragedtofind1methodstomeettheirtransportationneedsandre﹣discoverbusesbikesandtheirown2. Onthisdaypeoplegettogetherinthestreetsintersectionsandneighborhoodblocksto3theworldthatwedon'thavetoacceptourcar﹣controlledsociety. While4alongtheselineshadtakenplacefromtimetotimestarting5the1973oilcrisisitwasonlyinOctober19946astructuredcallforsuchprojectswas7inakeynotespeechbyEricBrittonattheInternationalAccessibleCitiesConferenceheldinToledoSpain. ThefirstnationalcampaignwaslaunchedinBritainin1997andtheFrenchfollowedsuitin1998.In2000carBustersissuedanopen8foraWorldCar﹣FreeDayto9withEurope'sCar﹣FreeDayonSeptember22.10thenwehavebeguntocallforcitizenstoorganize11onornearthisday. Howeverwedonotwant12onedayofcelebrationsandthenreturnto13life.WorldCar﹣FreeDayisthe14timetoremindcityplannersandpoliticiansto15cyclingwalkingandpublictransport.Itisuptouscitiesandgovernmentstohelp16permanentchangesto17pedestrianscyclistsandotherpeoplewhodonotdrivecars. While18accomplishmenthasbeenachievedintermsofmediacoveragetheseevents19tobedifficulttoachieverealsuccessandevenadecadelaterthereisconsiderableuncertaintyabouttheusefulnessofthisapproach.Broadpublicsupportand20tochangeisneededforsuccessfulimplementation执行. 1A.effective B.efficient C.useful D.alternative 2A.legs B.motors C.subway D.feet 3A.recall B.remind C.realize D.recommend 4A.projects B.events C.activities D.meetings 5A.as B.on C.with D.beyond 6A.when B.that C.where D.how 7A.undertaken B.submitted C.developed D.issued 8A.answer B.call C.wish D.longing 9A.connect B.involve C.consist D.concern 10A.Since B.Before C.After D.Right 11A.events B.affairs C.incidents D.accidents 12A.even B.still C.just D.ever 13A.usual B.previous C.ordinary D.average 14A.perfect B.limited C.accurate D.correct 15A.givewayto B.givepriorityto C.giveriseto D.giveinto 16A.employ B.decrease C.create D.increase 17A.assist B.benefit C.instruct D.influence 18A.constant B.similar C.envying D.considerable 19A.turnout B.workout C.carryout D.figureout 20A.approach B.attitude C.chance D.commitment
Thereareseveraldifferenttypesoffiredepartments.Somehirefull﹣timepaidfirefightersandsomearerunentirelybyvolunteers.1afirefightermustgothroughstrictphysicalandacademictrainingtoensureastrongknowledgeoffiresafetyandthephysicalstrengthtohandlethetasksrequiredbymembersofafiredepartment. Joiningafiredepartmentrequiresthatbothphysicalandwrittentestsarepassedwithscoresshowingathoroughknowledgeoffiresafety.2. Thefirststepinjoiningafiredepartmentasapaidfirefighteristosubmitanapplicationaswellasacquiretheappropriatetraining.Usuallyfirefightersmusthaveahighschooldiplomaandsomecompletetwo﹣or﹣four﹣yearprogramsinfirescienceatcommunitycollegesanduniversities.3andifacandidatealreadyhasconnectionsatafiredepartmenthemayapplyforapositionstraightoutofhighschool. Onceacandidateappliesandisacceptedfortrainingatafiredepartmenthemustthencompleteseveralweeksoftrainingatthedepartment'strainingcenter.4.Whenthisisdonethecandidateissenttoafirecompanyforaperiodofprobation实习.Hehastocontinuetraininginthenewpositionwhilebeingdirectedbyexperiencedfirefighters.5.Anapplicationmustbesubmittedtothevolunteerfiredepartmenttheniftheapplicationisacceptedthecandidatewilllakeatrainingprogramandthenberequiredtopassaphysicalandwrittentest.Firefightersmustalsobecomecertified认证asEmergencyMedicalTechniciansEMTs.ThelevelofEMTcertificationisdeterminedbytheindividualdepartments. A.Althoughitisdemanding B.Whichevertypeisdesired C.Howeveranacademicprogramisnotrequired D.Forvolunteerfirefighterstheprocedureissimilar E.Butjoiningavolunteerfiredepartmentistotallydifferent F.Trainingconsistsofclassroomworkandpracticaltraining G.Alsoacandidatemustbeabletorespondquicklyinemergencies
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FromAntiguatoZanzibarfthesespotspromiseanincredibletripfor2019. AntiguaGuatemala Antiguaiswortheverypennybutthatdoesn'tmeanyou'llhavetoemptyyourwalletsaysHudson.Thereareplentyofbudgel﹣carisciousactivities.Itwon'tcostyouacointovisitSantoDomingodelCerroanoutdoorsculpturepark.Wantingsomethingsweet?HeadtoChocoMuseo.Admissionisfreeandsoarethesamples! OdessaUkraine Odessaishavingabitofatourismboomnationwide﹣notthatwe'resurprisedgivenitssandybeachesandpastel﹣coloredbuildings﹣butit'sstillfairlyundertheorderforinternationalaudiences.Youcanalsocountonthisportcityforaffordablefun.TicketstotheOdessaOperaHousestartatamere﹩2! BogotaColombia TravelersonbudgetwillfindColombia'svastcapital.farmoreofabargainandeverybitasfascinatingsaysHudson.It'sfreetovisitMuseodeOroandonSundaysmanyofthebigroadsareclosedtoaccommodatefoodcartsstreetentertainersandpedestrians. Zanzibar Zanzibarattractsvacationerswithitswhitesandbeachesgreenish﹣blueddescolorfulcoralreefsandoceanfrontseaside.OfcoursewanderinginhistoricStoneTownisprettyappealingtoo.Eitherwayyouneedn'tspendapennyinthisamazingplace.It'salsoworthnotingthatJozaniForestistheonlyplaceintheworldyoucan9eeendangeredredcolobusmonkeys. 1Whichofthefollowingrequiresadmissionfee? A.ChocoMuseo. B.StoneTown. C.MuseodeOro. D.OdessaOperHouse. 2WhatisspecialtoZanzibar? A.Whitesandbeaches. B.Colorfulcoralreefs. C.Redcolobusmonkeys. D.HistoricStoneTown. 3Whatdothefourdestinationshaveincommon? A.Theyarecoastalcities. B.Theyareinexpensivetovisit. C.Theywelcomestreetentertainers. D.Theywillmakeyourwalletempty.
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假定英语课上老师要求同桌之间交换修改作文请你修改你同桌写的以下作文.文中共有10处语言错误每句中最多有两处.每次错误仅涉及一个单词的增加删除或修改. 增加在缺词处加一个漏字符号∧并在其下面写出该加的词. 删除把多余的词用\划掉. 修改在错的词下画一横线并在该词下面写出修改后的词. 注意1.每处错误及其修改均仅限一词; 2.只允许修改10处多者从第11处起不计分. Mauritiusanislandnationisworkingtogetridoffossilfuelsbyreplacethemwithsugarcanestalks.Anislandhasreliedonimportedgasasfuelforlongbutitpointsoutwhichitsmaincashcropisprovidingamoreeconomicalchoice. Onceasugarcanestalkhassqueezedapileofdrystalksremain.Theseleftoversarethenburnedtogeneratepoweranditaccountsfor14percentsoftheisland'senergyneeds. Sugarcanesthenation'smaincashcropcontinuesleadingthechargetowardsamoreenvironmentalfriendlyfuture.Currentlyfoursugarcompaniesrunhisownpowerstationtogetherwithgeneratingupto60%oftheisland'selectricity.Howeverthecarbondioxidegeneratedbytheburningprocessisthenusedtoaddtosoftdrinks.
Balletisaformalkindofdanceperformancewitharichandinterestinghistory.ThewordballetcomesfromtheFrenchlanguageand1bebasedontheItalianwordballetto.Ballettomeansalittledance.Ballet'searlyrootsbeganinItalyinthelate1400s.ButitwasinFrance2balletdevelopedintotheformweknowtoday. TheFrenchrulerLouistheFourteenthhadabiginfluence3thedirectionofballetinitsearlyhistory.HeruledFranceforseventy﹣twoyears4startin1643.Hestarteddancingasaboyandworkedharddaily. LouistheFourteenthturnedballetintoaformofdancethatreflected5hepowerandinfluence.Ballet'smanyrulesand6extremedetailedmovementsexpressedaperson'spowerandsocialrelations.Thekingmadesurethatballetbecamea7requireforthepeopleofhiscourt.HealsostartedtheRoyalAcademyofDance8importantpeoplecouldlearnthisart.Theaimofthisdancewasself﹣controlorderandperfection. Balletslowlychangedfromadanceattheking'scourttoone9performbyprofessionaldancers.WhenLouistheFourteenthdiedin1715ballet10bringtoodierpartsofEuropeandwasdevelopinginotherways.
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