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在空间四边形ABCD各边AB、BC、CD、DA上分别取E、F、G、H四点，如果EF、GH相交于点P，那么（ ）
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空间四边形ABCD中若AB＝BC＝CD＝DA＝AC＝BCE.F.G.H.分别是AB.BC.CD.DA
平行四边形
长方形
菱形
正方形
已知四边形ABCD则下列说法中正确的是
若AB∥CD，AB=CD，则四边形ABCD是平行四边形；
若AC⊥BD，AC=BD，则四边形ABCD是矩形；
若AC⊥BD，AB=AD，CB=CD则四边形ABCD是菱形；
若AB=BC=CD=AD，则四边形ABCD是正方形；
已知四边形ABCD则下列说法中正确的是
若AB∥CD，AB=CD，则四边形ABCD是平行四边形
若AC⊥BD，AC=BD，则四边形ABCD是矩形
若AC⊥BD，AB=AD，CB=CD则四边形ABCD是菱形
若AB=BC=CD=AD，则四边形ABCD是正方形
如图26凸四边形ABCD的四边ABBCCD和DA的长分别是3412和13∠ABC=90°则四边形AB
如图在四边形ABCD中E.为AB上一点△ADE和△BCE都是等边三角形ABBCCDDA的中点分别为P
在空间四边形ABCD中E.F.分别为ABAD上的点且AE∶EB＝AF∶FD＝1∶4又H.G.分别为B
BD∥平面EFG，且四边形EFGH是平行四边形
EF∥平面BCD，且四边形EFGH是梯形
HG∥平面ABD，且四边形EFGH是平行四边形
EH∥平面ADC，且四边形EFGH是梯形
已知如图在四边形ABCD中EFGH分别是ABBCCDDA的中点.求证:四边形EFGH是平行四边形.
在空间四边形ABCD各边AB.BC.CD.DA上分别取E.F.G.H.四点如果EFGH相交于点P.那
点P.必在直线AC上
点P.必在直线BD上
点P.必在平面DBC内
点P.必在平面ABC外
在空间四边形ABCD的边ABBCCDDA上分别取点E.F.G.H.如果EHFG相交于一点M.那么M.
我们给出如下定义顺次连接任意一个四边形各边中点所得的四边形叫中点四边形.1如图1四边形ABCD中点E
我们给出如下定义顺次连接任意一个四边形各边中点所得的四边形叫中点四边形.1如图1四边形ABCD中点E
我们给出如下定义顺次连接任意一个四边形各边中点所得的四边形叫中点四边形.1如图1四边形ABCD中点E
我们给出如下定义顺次连接任意一个四边形各边中点所得的四边形叫中点四边形.1如图1四边形ABCD中点E
空间四边形ABCD各边AB.BC.CD.DA上分别取E.F.G.H.四点如果EFGH=P则点P
一定在直线BD上
一定在直线AC上
在直线AC或BD上
不在直线AC上也不在直线BD上
如图在四边形ABCD中对角线AC.BD相交于点O.下列条件不能判定四边形ABCD为平行四边形的是
AB∥CD，AD∥BC
OA=OC，OB=OD
AD=BC，AB∥CD
AB=CD，AD=BC
我们给出如下定义顺次连接任意一个四边形各边中点所得的四边形叫中点四边形.1如图1四边形ABCD中点E
已知空间四边形ABCD.1求证对角线AC与BD是异面直线;2若AC⊥BDEFGH分别这四条边ABBC
在空间四边形ABCD各边ABBCCDDA上分别取E.F.G.H.四点如果EFGH相交于点P.那么
点P.必在直线AC上
点P.必在直线BD上
点P.必在平面DBC上
点P.必在平面ABC外
我们给出如下定义顺次连接任意一个四边形各边中点所得的四边形叫中点四边形.1如图1四边形ABCD中点E
空间四边形ABCD中P.Q.R.分别ABADCD的中点平面PQR交BC于S求证四边形PQRS为平行四
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下列有机物系统命名正确的是
如图反比例函数y＝x＞0的图象经过矩形OABC对角线的交点M分别交ABBC于点DE．若四边形ODBE的面积为12则k的值为．
如图在菱形ABCD中已知AB＝4∠ABC＝60°∠EAF＝60°点E在CB的延长线上点F在DC的延长线上有下列结论①BE＝CF②∠EAB＝∠CEF③△ABE∽△EFC④若∠BAE＝15°则点F到BC的距离为2﹣2．则其中正确结论的个数是
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如图⊙O的直径AB垂直于弦CD垂足是点E∠CAO＝22.5°OC＝6则CD的长为
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如图1在平面直角坐标系中抛物线y＝﹣x2+bx+c经过点A﹣50和点B10． 1求抛物线的解析式及顶点D的坐标 2点P是抛物线上AD之间的一点过点P作PE⊥x轴于点EPG⊥y轴交抛物线于点G过点G作GF⊥x轴于点F当矩形PEFG的周长最大时求点P的横坐标 3如图2连接ADBD点M在线段AB上不与AB重合作∠DMN＝∠DBAMN交线段AD于点N是否存在这样点M使得△DMN为等腰三角形若存在求出AN的长若不存在请说明理由．
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如图在岷江的右岸边有一高楼AB左岸边有一坡度i＝12的山坡CF点C与点B在同一水平面上CF与AB在同一平面内．某数学兴趣小组为了测量楼AB的高度在坡底C处测得楼顶A的仰角为45°然后沿坡面CF上行了20米到达点D处此时在D处测得楼顶A的仰角为30°求楼AB的高度．
8分Aslifeexpectancyincreasesnowadaystheaveragepersonliveswellbeyondtheageofretirement.Asaresulttheelderlymakeupanever﹣increasingpercentageofsocietywhichmakesitmoreimportantthaneverforarealefforttobemadeinimprovingthelivesofseniorcitizens. Onewaytodealwiththesituationwouldbetoensurethattheelderlyhaveenoughmoneyonwhichtolive.Obviouslywhenapersonstopsworkingtheystillrequireasourceofincometocovertheirbasicneedssuchasfoodaccommodationandheating.Aclearsolutiontotheproblemisforthegovernmenttomakesurethatthestatepensionisadequatefortheseneeds. Stepsshouldalsobetakentoovercomethehealthproblemstheelderlyface.Thegovernmentshouldalsoprovideaccesstothebesthealthcareavailablewhichmaynecessitatepayingforresidentialhomeswheretheelderlycanhaveround﹣the﹣clocknursingorattheveryleastprovidingmedicationfreeofchargetoallpeopleoveracertainage. Thelivesofoldpeoplecouldbeimprovedifattemptsweremadetoaddresstheproblemofsocialisolation.Ifweorganisedtripsfortheelderlytocommunitycentresvisitsfromsocialworkerstheirproblemoflonelinesscanbereducedalotwhichmarksthelivesofsomanyoldpeoplelivingaloneandfarfromtheirfamilies. Onefinalsuggestionwhichwouldhelpenormouslyistochangetheattitudeofthecommunitytowardsitsoldermemberswhoarealltoooftenseenasaburdenonsocietyanddismissedashavinglittletodowithmodernlife.Weneedtobetaughtfromanearlyagetorespecttheviewsofoldpeopleandappreciatetheirbroaderexperienceoflife.Thiswouldhelpsocietyasawholeandencourageappreciationoftherolethatoldpeoplecanstillplaytoday. 1.Whatdoesthepassagemainlytalkabout? A.Alltheelderlycanenjoyfreemedication. B.Thenursescantakegoodcareoftheelderly. C.Somesuggestionswouldbemadetoimprovethelivesoftheelderly. D.Thehealthcareavailabletotheelderlyisgood. 2.TheunderlinedwordaddressinParagraph4probablymeans. A.findout B.dealwith C.putdown D.pickup 3.Whatfactorsaffectedtheoldpeople'slife? a.thestatepension b.thebasicneeds c.theattitudeofthecommunity d.theexperienceoflife e.socialisolation f.medicalcare A.abcd B.bcde C.cdef D.acef 4.Accordingtothelastsuggestiontheoldpeople. A.shouldberespectedbyallofus B.havetogathermorelifeexperience C.mayberegardedasourheavyburden D.mustchangetheirattitudetothecommunity
6分EachmorningGrandpawasupearlysittingatthekitchentablereadinghisbook.Hisgrandsonwantedtobejustlikehimandtriedtocopyhimineverywayhecould.OnedaythegrandsonaskedGrandpaItrytoreadthebookjustlikeyoubutIdon'tunderstanditandIforgetwhatIunderstandassoonasIclosethebook.Whatgooddoesreadingthebookdo? ThegrandpaquietlyturnedfromputtingcoalinthestoveandrepliedTakethiscoalbasketdowntotheriverandbringmebackabasketofwater.Theboydidashewastoldbutallthewaterleakedoutbeforehegotbacktothehouse.ThegrandpalaughedandsaidYou'llhavetomovealittlefasternexttimeandsenthimbacktotheriverwiththebaskettotryagain. Thistimetheboyranfasterbutagainthebasketwasemptybeforehereturned.Outofbreathhetoldhisgrandpathatitwasimpossibletocarrywaterinabasketsohewenttogetabucketinstead.ThegrandpasaidIdon'twantabucketofwater;Iwantabasketofwater.You'rejustnottryinghardenough. Theboyagaindippedthebasketintotheriverandranhardbutwhenhereachedhisgrandpathebasketwasemptyagain.OutofbreathhesaidGrandpait'suseless!Soyouthinkitisuseless?thegrandpasaidLookatthebasket. Theboylookedatthebasketandforthefirsttimeherealizedthatthebasketwasdifferent.Ithadbeentransformedfromadirtyoldcoalbasketandwasnowclean.Grandsonthat'swhathappenswhenyoureadthebook.Youmightnotunderstandorremembereverythingbutwhenyoureadityou'llbechangedinsideandout. 1.Whatpuzzledthegrandsonmostwas. A.whetheritwasusefultoreadbooks B.whyheforgotwhathereadsoon C.whatkindofbookhecouldunderstand D.howhecouldreadbookslikehisgrandpa 2.WhydidGrandpaaskhisgrandsontofetchabasketofwater? A.Totrainhimtorunfaster. B.Tocleanthedirtybasketintheriver. C.Topunishhimfornotreadingcarefully. D.Togethimtorealizetheuseofreadingbooks. 3.Whatlessoncanwelearnfromthestory? A.Theoldarealwayswiserthantheyoung. B.Itisfoolishtocarrywaterwithabasket. C.Readingbookscanchangeapersongradually. D.Youcan'texpecttorememberwhateveryouread.
下列离子方程式书写正确的是
PM2.5是指大气中直径小于或等于2.5微米的颗粒物也叫可入肺颗粒物与肺癌哮喘等疾病的发生密切相关是灰霾天气的主要原因．它主要来自化石燃料的燃烧如机动车尾气燃煤等．下列与PM2.5相关的说法不正确的是
10分Justlikechildrenbabyanimalsspendcountlesshoursatplay.Afterstudyinganimalplayformanyyearsscientistsrecognizethatyounganimalplayispracticeforadultbehavior.Todaythisplayisroughlydividedintothefollowinggroups. Locomotorplayreferstothemovementsanimalscarryoutintheirplay.Runningleapingturningandkickingaresomeofthemostcommonexamplesoflocomotorplay.Anadultdeermayrunleapandtwisttoescapeitsattackers.Playmovementslikethesesurelymakeyounganimalsnimble.Somedaytheseskillsmighthelpsavetheirlives. Movingforwardslowlyattackingsuddenlyandbitingareexamplesofpredatoryplaythathelpyoungpredatorsprepareforalifeofrunningafterandtakingholdofotheranimals.Wildcatswolvesandbearsarepredators.Itisverycommontoseetheseyounganimalsplaythiskindofgameswhichsharpentheirskillsandteachthemabouttheirstrengthsandlimitations. Forchildrenplayingwithtoysisbothfunandeducational.Ithelpsimprovetheirhandandeyemovementsaswellasdevelophandskillstoaccomplishtasks.Itisthesamewithanimals.Youngchimpanzeesimprovetheirhandskillswhileplayingwithsticks.Birdsalsoplaywiththingsinwaysthatteach.Swallowsdropandrecoverfeathersinmidair.Divingsuddenlytocatchthefeathersisagoodpracticeforcatchingflyinginsects. Socialplayhelpsanimalslearnhowtobehavewhentheyrunintootheranimals.Anditteachesanimalsaboutcommunication.Ananimalgivessignalstoletanotheranimalknowitwantstoplay.Manyanimalsgivesignalsbyshowingaplayface.Insomewaysthisfaceislikeahumansmile;theanimalholdsitsmouthinarelaxedandopenmanner.Duringplay﹣fightssomeanimalsmaystepbackwardstosignalthattheyareplayingandnotactingseriously. Untilnowscientistshaveunderstoodplayfulactshelpprepareanimalsfortheirseriousadultsituations.Butthenumbersofplayfulspeciesandexamplesofanimalplayarevast.Thepurposeofanimalplaymayhavemeaningsscientistshavenotdiscoveredyet. 1.Themainpurposeofthetextisto. A.askustotakegoodcareofwildanimals B.encourageustolearnmoreaboutanimals C.entertainuswithinterestinganimalstories D.showussomethingaboutanimalbehavior 2.TheunderlinedwordnimbleinParagraph2canbestbereplacedby. A.cruel B.swift C.curious D.strong 3.Whichofthefollowingbelongstopredatoryplay? A.Adeerrunsleapsandturns. B.Achimpanzeeplayswithastick. C.Alionmovesslowlyandmakesanattacksuddenly. D.Adogholdsitsmouthinarelaxedandopenmanner. 4.BasedonParagraph5aplayfaceis. A.atypeofsignalbetweenanimals B.anameforakindofanimalplay C.anactivitythatinvolvesadultanimals D.anactionthatistaughttoanotheranimal 5.Whichofthefollowingshowsthestructureofthetext?
下列分离或提纯物质的方法正确的是
15分Agroupoffrogsweretravelingthroughthewoodsandtwoofthem1fallintoahole.Alltheotherfrogslookeddown.Whentheysawhowdeep2holewastheytoldthetwofrogsthattheywoulddiesoon. Atfirstbothofthetwofrogsdidn'tcaretheirwordsandtried3besttojumpoutofthehole.Theotherfrogskepttellingthemtostopbecausetheythoughttherewasnochance4jumpoutofsuchadeephole.Finallyoneofthetwofrogsbelievedthesewordsandgaveup.Hefelldownanddied. Theotherfrogcontinuedtojumpashardashecould.Onceagainthecrowdoffrogsshoutedathimtostopthepainandjustdie.Hejumpedeven5hardandfinallysucceeded.WhenhegotouttheotherfrogsaskedDidn'tyouhearus?6theirgreatsurprisethefrogturnedouttobedeaf.Hethoughttheywerehelpinghimallthetimenot7stophim. Thisstoryteachestwolessons:Thereispoweroflifeanddeathinthetongue.Well﹣meantwordscanhelppeopleintrouble.Butevilwordssometimescankillthem.Becarefulof8yousay. Rememberthepowerofwords.Anyonecanspeakwords9arelikelytomakepeoplegiveupindifficult10time. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
设NA表示阿伏加德罗常数下列叙述中正确的是
6分Noonewouldmuchliketheideaofeating61poundsoftomatoesaday.Butiftheirgoodnesswasputintoaneasy﹣to﹣swallowpillthatyouweretoldmightpreventstrokes中风andheartattacksyouwouldprobablybeputtinginanordertomorrow. Researchersbelievetheymayhavecomeupwithjustthataftertrials.Thedailypillcontainsachemicalcalledlycopenewhichmakestomatoesredandisknowntobreakdownfatinthevessels血管.ACambridgeUniversitystudyfoundtakingthepillsimprovedbloodflowandtheliningofvesselsinpatientswithpre﹣existingheartconditions.Italsoincreasedtheflexibilityoftheirvesselsby50percent.Thescientistsbelieveitcouldlimitthedamagecausedbyheartdisease﹣responsiblefor180000deathsayear﹣andhelpcutthe49000deathsayearfromstrokes.Theyalsohopeitcouldbenefitthosewitharthritis关节炎diabetes糖尿病andevenslowtheprogressofcancer. Eachpillisequaltoeatingaround61poundsofripetomatoes.StudieshaveshowneatingaMediterranean﹣styledietrichintomatoesfishvegetablesnutsandoliveoilcansignificantlyreducecholesterol胆固醇andhelppreventcardiovasculardisease. Preliminaryresultsfromatwo﹣monthtrialinwhichthepillwasgivento36heartdiseasepatientsand36healthyvolunteerswithanaverageageof67werepresentedatameetingoftheAmericanHeartAssociation.Itwasshowntoimprovethefunctionoftheendothelium﹣thelayerofcellsliningbloodvessels.Italsoimprovedtheirsensitivitytonitricoxidethegaswhichcausestheenlargementofthevesselsinresponsetoexercise. IanWilkinsonheadofCambridgeUniversity'sclinicaltrialsunitsaidTheseresultsarepotentiallyverysignificantanditmeetsthegoalbutweneedmoretrialstoseeiftheytranslateintofewerheartattacksandstrokes. Furtherstudiesareplannedwithresearchershopingitcouldofferachoiceforheartdiseasesuffererswhocannottakethecholesterol﹣lowingdrugs. MikeKnaptonheadoftheBritishHeartFoundationsaidAlthoughthisshowedlycopeneimprovedbloodflowinpeoplewithheartdiseasethat'salongwayfromdemonstratingthattakingitcouldimproveoutcomesforpeoplewithheartdisease.Thebestwaytogetthebenefitsofagooddietistoeatplentyoffreshfruitandvegetables. 1.WhatcanweinferfromParagraph1? A.Wecaneattoomuchtomatofood. B.Tomatoesarehelpfultostrokesandheartattacks. C.Tomatoeswilllosehealthyelementswereputintopills. D.Wehadbetternoteattomatoes. 2.Wecanlearnfromthepassagethatthepills. A.areattheexperimentstage B.cancureallthedisease C.arewidelyusedamongpatients D.costpatientssolittlemoney 3.WhatWasIanWilkinson'sopiniononthetrial? A.Disappointing. B.Surprising. C.Satisfactory. D.Terrible.
下列关于合成材料的说法中不正确的是
6分NingZetaohasbecomeChina'snewswimmingstarduetohisamazingperformanceatthe2014AsianGamesinIncheon仁川SouthKorea.Withalreadytwogoldmedalsinhandthe21﹣year﹣oldclocked47.70secondsinthe100mfreestylesettinganewAsianrecord.ThisresulthasbeenrecognizedbyFINAastheworld'sthirdbesttimethisyearfastenoughtohavewonagoldmedalinlastyear'sBarcelonaWorldChampionships.ItismyfirstinternationaleventsaidNingwholaterwonafourthgoldmedalinIncheon.Iamhappythatmyresultsareprettyclosetomypersonalbest. BorninthecentralChinesecityofZhengzhouNingenteredthelocalteamattheageof11andjoinedthenavyteamin2007.Hefirstcaughtpeople'sattentionin2009whenhefinishedeighthinthe200mindividualmedley混合泳attheNationalGames. NeverthelessNingsufferedfromboneinfectioninbothkneesforalongtimewhichmadehimunabletotrainhardonhiskicks.Healsohadanindigestionproblemandhadtoeatsoftfoodwhichiseasytodigest.Hispoorstomachevenmadeitimpossibleforhimtocompleteweek﹣longfulltimetraining.Buttheyoungswimmernevergivesup.HisidolisthegreatRussianswimmerAlexanderPopovwhocontinuedtowinOlympicgoldmedalsafterhewasstabbed刺伤onastreet.NingsaidHewasarealfighterandIneedtolearnfromhim. TakenbettercareofbycoachesanddoctorsNingcannowtrainasnormallyasothers.Andthatiswhyhecangettoday'sachievements.ThegoldmedalsattheAsianGamesalsoboostedtheconfidenceofthenewswimmingstarwhohopestoenterthenationalteamandcompeteforChinainmoreinternationalevents.Chinesemaleswimmershaveneverbeenplacedamongtopeightintheshort﹣distancefreestylehesaid.IhopeIcandoitjustlikewhatSunYangdidinthemid﹣longdistancefreestyle. 1.Thebesttitlecouldbe. A.NingZetaoaworldfamousswimmer B.NingZetaoapromisingrisingstar C.NingZetaoastrong﹣willedsoldier D.NingZetaoaworldgoldmedalist 2.Wecanlearnfromthepassagethat. A.theresultsNinggotinIncheonarehisbest B.Ningisgoodatboth100mand200mfreestyle C.NingbrokeanAsianrecordatthe2014AsianGames D.Ninghasalreadygot5goldmedalsintheinternationalevent 3.Itcanbeinferredfromthepassagethat. A.somehealthproblemshavelittleeffectonNing'straining B.beingwellcaredofisthemainreasonforNing'sachievements C.theChineseswimmershavenevergotintothetopeighthintheworldevent D.goldmedalistasNingisheisnotyetamemberofNationalSwimmingTeam
25分假定你是希望中学学生李华得知2017年香港大学要在大陆进行自主招生的消息后有意向香港大学申请参加自主招生考试请用英语写一封自荐信主要包括:1.个人信息2.性格爱好与特长3.学习情况注意:1.词数100左右;2.信的开头已为你写好不计入总词数;3.可根据内容要点适当增加细节以使行文连贯.4.参考词汇:自主招生independentrecruitmentDearSirMynameisLiHuafromHopeHighSchool.YoursLiHua.
某班七个兴趣小组人数如下566x789已知这组数据的平均数是7则这组数据的中位数是
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