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在△ABC中，D为BC边上一点，E是AD中点，若＝，＝+，则λ+μ＝（ ）
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高三下学期数学《》真题及答案
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如图等边△ABC的边长为4AD是BC边上的中线F.是AD边上的动点E.是AC边上一点若AE=2当EF
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在△ABC中AD是BC边上的中线点E.是AD中点过点E.作垂线交BC于点F.已知BC=10△ABD的
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如图在△ABC中D.是BC边上的中点且AD=ACDE⊥BCDE与AB相交于点E.EC与AD相交于点F
如图等边△ABC的边长为6AD是BC边上的中线M.是AD上的动点E.是AC边上一点若AE=2EM+C
如图等边△ABC的边长为4AD是BC边上的中线F.是AD边上的动点E.是AC边上一点若AE=2当EF
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如图以△ABC的BC边上一点O为圆心的圆经过AB两点且与BC边交于点ED为BE的下半圆弧的中点连接A
已知如图在△ABC中D.是BC边上的一点连结AD取AD的中点E.过点A.作BC的平行线与CE的延长线
如图在△ABC中若AD⊥BC点E.是BC边上一点且不与点B.C.D.重合则AD是几个三角形的高线
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在Rt△ABC中∠BAC=90°AB=AC点D为BC的中点点E为AB边上一点若BC=8DE=5则线段
△ABC中D.为BC边上一点BC=3BDAD=∠ADB=135°.若AC=AB则BD=_____.
已知如图在△ABC中D.是BC边上的一点连结AD取AD的中点E.过点A.作BC的平行线与CE的延长线
如图在四棱锥S―ABCD中SA⊥底面ABCD∠BAD=∠ABC=90°.SA=AB=AD=BC=1E
已知等腰△ABC中AB=ACD.为BC边上一点连结AD若△ACD和△ABD都是等腰三角形则∠C.的
如图D为△ABC的BC边上的任意一点E为AD的中点△BEC的面积为5则△ABC的面积为.
在Rt△ABC∠C=90°D为AB边上一点点MN分别在BC.AC边上且DM⊥DN.作MF⊥AB于点F
如图等边△ABC的边长为4AD是BC边上的中线F.是AD边上的动点E.是AC边上一点若AE=2当EF
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如图所示在四棱锥S―ABCD中SA⊥底面ABCD∠BAD=∠ABC=90°SA=AB=AD=BC=1
已知如图在△ABC中D.是BC边上的一点连结AD取AD的中点E.过点A.作BC的平行线与CE的延长线
如图△ABC是等边三角形点D.是边BC上的一点以AD为边作等边△ADE过点C.作CF∥DE交AB于点
如图在△ABC中若AD⊥BC点E.是BC边上一点且不与点B.C.D.重合则AD是几个三角形的高线
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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.
小轿车驾驶室内装有冷暖空调可使小轿车内冬暖夏凉但是在使用空调过程中常易造成前方玻璃模糊影响视线对此叙述正确的有
实验室常用的电流表和电压表都由电流计G其实就是小量程的电流表改装而成的．电流计G也是有电阻的同样遵从欧姆定律．现有一个满偏电流量程为3.0mA内阻为Rg＝1Ω的电流计G．小明同学利用所学的物理知识将该电流计G改装成了一个既可以测量电流也可以测量电压的多用电表其电路原理如图所示．当接AB两个接线柱时可以当作量程是0.6A的电流表使用当接AC两个接线柱时可以当作量程为3V的电压表使用求电阻R1R2的阻值大小结果保留三位小数．
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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.
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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．
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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
用如图所示装置测量动滑轮的机械效率实验时竖直向上的匀速拉动弹簧测力计使挂在动滑轮下面的钩码缓缓上升．实验数据如表 1第①次实验时使钩码匀速升高0.2m所用的时间为2s则作用在绳子自由端的拉力F的功率为0.12W 2第②次实验时测得该动滑轮的机械效率约为90.9%结果保留到0.1% 3提高动滑轮机械效率的办法除了增加所提升的物体钩码的重量还可以减轻动滑轮的重量．如图所示若两次提升同一物体第一次所用的动滑轮重为G1时此时动滑轮的机械效率为75%第二次所用的动滑轮重为G2时此时动滑轮的机械效率为90%则G1与G2之比为31不计绳重及摩擦．
如图所示将同一长方体分别水平与竖直放置在水中都能保持静止下列关于该长方体处于这两种情形的有关分析正确的是
如图所示O是支点在B端挂一重物可以在A端沿不同的方向分别施加F1F2F3三个力均可使杠杆在水平位置保持平衡下列关于这三个力大小关系的表达式正确的是
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标有6V1.5W的小灯泡通过它的电流随两端电压变化的关系如图所示若把这样的三只灯泡串联起来接在12V的电源两端灯泡的实际功率约为W
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如图是自动测定油箱内油量的装置图油量表相当于电压表其中R0是一定值电阻R是弧形变阻器它的金属滑片P是杠杆的一端O为杠杆支点下列判断正确的是
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如图1灯距地面的高度为H身高为h的人自路灯的正下方经过看到自己头部的影子正好在自己脚下．如图2如果人以不变的速度v匀速向前走由A到B则人头部的影子由C运动到D．证明人头部影子的速度为．
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.
面镜不是使光线透过而是使光反射回去的仪器光线遵循反射定律如图甲是凹面镜它将平行主轴的入射的光线会聚在焦点F上这是因为表面每个点的法线方向不同光线以不同的角度反射根据光路可逆性凹面镜不仅可以使平行光线汇聚于焦点还能使过焦点的光线反射成平行于主轴的光请根据以上叙述在图乙中画出H0的成像光路图．
青春期后男生的声音变得“低沉”了这里的“低”主要指的是
在物理学中物体由于被举高而具有的能叫做重力势能可用Ep表示重力势能Ep与物体的质量m与被举的高度h之间的定量关系可用Ep＝mgh表示物体由于运动而具有的能叫动能可用Ek表示物体的动能与物体的质量m运动速度v的定量关系可用Ek＝mv2表示．如图所示一个质量m为5kg的物体从斜长s为10m倾角θ为30°的光滑斜面顶端由静止自由滑行到斜面底部不计空气阻力请完成下列问题 1求该物体自斜面顶端由静止自由滑行到斜面底部的过程中重力对物体做功多少焦耳 2由于斜面光滑且不计空气阻力则乙物体从斜面顶端滑行到斜面底部的过程中其机械能守恒．求该物体从斜面顶端由静止自由滑行到斜面底端的瞬时速度大小为多少
如图是某些细胞器的亚显微结构模式图相关叙述错误的是
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