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在三棱锥P﹣ABC中,△ABC是边长为4的等边三角形,平面PAB⊥平面ABC,,点M为棱BC的中点,点N在棱PC上且满足,已知使得异面直线MN与AC所成角的余弦值为的λ有两个不同的值λ1,λ2(λ1...
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已知三棱锥P﹣ABC中底面△ABC是边长为3的等边三角形侧棱长都相等.表面积为16π的球O过三棱锥
在三棱锥P﹣ABC中△ABC是等边三角形PB⊥底面ABCAB=2PB=2则该三棱锥的外接球的表面积
如图在三棱锥E.-ABC中平面EAB⊥平面ABC三角形EAB为等边三角形AC⊥BC且AC=BC=OM
2018年·赤峰模拟理科4月三棱锥P﹣ABC中PA⊥平面ABC且PA=3△ABC是边长为的等边三角形
如图所示在三棱锥S.—ABC中SO⊥平面ABC侧面SAB与SAC均为等边三角形∠BAC=90°O.为
在三棱锥S.﹣ABC中底面ABC是边长为3的等边三角形SA⊥SCSB⊥SCSA=SB=2则该三棱锥的
将边长为1的正方形ABCD沿对角线AC折起使得平面ADC⊥平面ABC在折起后形成的三棱锥D.﹣ABC
若沿△ABC三条边的中位线折起能拼成一个三棱锥则△ABC
一定是等边三角形
一定是锐角三角形
可以是直角三角形
可以是钝角三角形
5.00分在三棱锥P﹣ABC中△ABC为等边三角形PA=8PB=PC=AB=3则三棱锥P﹣ABC的
76π
75π
78π
77π
在三棱锥P.-ABC中△PAC和△PBC是边长为的等边三角形AB=2O.是AB的中点.1在棱PA上求
在三棱锥P﹣ABC中平面PAB⊥平面ABC△ABC是边长为6的等边三角形△PAB是以AB为斜边的等
64π
48π
36π
27π
三棱锥P﹣ABC中△ABC为等边三角形PA=PB=PC=2PA⊥PB三棱锥P﹣ABC的外接球的表面积
5.00分在三棱锥P﹣ABC中平面PAC⊥平面ABCAB⊥BC△PAC为等边三角形若则三棱锥P﹣A
如图在三棱锥V-ABC中平面VAB⊥平面ABC△VAB为等边三角形AC⊥BC且AC=BC=OM分别为
已知三棱锥P﹣ABC△ABC为等边三角形△PAC为直角三角形∠PAC=90°∠PCA=30°平面P
三棱锥P﹣ABC的底面ABC是等腰三角形∠C=120°侧面PAB是等边三角形且与底面ABC垂直AC
已知三棱锥P﹣ABC的底面ABC是边长为2的等边三角形PA⊥平面ABC且PA=2则该三棱锥外接球的
20π
48π
2018年·大庆二模已知三棱锥S﹣ABCSA⊥平面ABC△ABC为等边三角形SA=2AB=3则三棱锥
如图以等腰直角三角形ABC的斜边BC上的高AD为折痕把△ABD和△ACD折成互相垂直的两个平面后某学
如图在三棱锥S—ABC中侧面SAB与侧面SAC均为等边三角形∠BAC=90°O为BC中点. 1证明
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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
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.
下列关于细胞分裂分化衰老和凋亡的叙述中正确的是
在豌豆杂交实验中为防止自花传粉应
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
一般情况下活细胞中含量最多的化合物是
下列群落演替的实例中属于初生演替的是
一定属于一对同源染色体的是
决定自然界中生物多样性和特异性的根本原因是生物体内
下列关于现代生物进化理论的叙述正确的是
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
如图为遗传学中的中心法则图解图中①②③分别表示的过程是
一分子ATP中含有的高能磷酸键和磷酸基团的数目分别是
某生物的体细胞含有42条染色体在减数第一次分裂四分体时期细胞内含有的染色单体染色体和DNA分子数依次是
下列物质不能作为调节生命活动的信息分子的是
如图是某草原生态系统中部分生物之间关系的示意图请根据图回答下列问题. 1图中鼠和食草昆虫属于第营养级. 2该生态系统中许多食物链彼此交错连接成. 3图中最长的食物链是. 4若该草原被火灾毁灭多年后重新演替为草原这种演替方式属于演替.
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.
一个DNA分子复制完毕后新形成的DNA子链
下列各对性状中属于相对性状的是
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假定你是李华你和几个朋友打算去参观茶园想邀请美国交流生Henry同往.请你给他写封邮件告知活动安排.内容包括 1.时间和地点; 2.学习如何沏茶品茶; 3.介绍中国茶文化的历史和发展. 注意 1.词数100左右; 2.可以适当增加细节以使行文连贯. DearHenry Yours LiHua
如图是三个相邻的植物细胞之间水分流动方向示意图.图中三个细胞的细胞液浓度关系是
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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