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已知18x=2y=3,则=( )
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高三上学期数学《》真题及答案
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已知代数式x﹣2y的值是3则代数式1﹣2x+4y的值是.
已知长方形的面积为18x3y4+9xy2﹣27x2y2长为9xy则宽为
2x
2
y
3
+y+3xy
2x
2
y
2
﹣2y+3xy
2x
2
y
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+2y﹣3xy
2x
2
y
3
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已知x﹣2y=3则7﹣2x+4y的值为
﹣1
0
1
2
已知[x﹣y2﹣x+y2+y2x﹣y]÷﹣2y=2求的值.
已知两点
(1,-2),
(-4,-2)及下列四条曲线: ①4x+2y=3 ②x
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2
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=3 其中曲线上存在点P.,使|PA|=|PB|的曲线有( ) A.①③B.②④
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已知x﹣2y=3则代数式2y﹣x2﹣2x+4y﹣1的值为.
已知|x+3|+y﹣22=0求x﹣2y的值.
已知4x=3y求代数式x﹣2y2﹣x﹣yx+y﹣2y2的值.
已知代数式x﹣2y的值是3则代数式15﹣2x+4y的值是.
已知x﹣2y=3那么代数式3﹣2x+4y的值是
﹣3
0
6
9
已知﹣x+2y=3则3x﹣2y2﹣5x﹣2y+6的值是
﹣6
18
38
48
已知z=x﹣2y其中xy满足不等式组则z的最小值为
已知x>y则下列不等式不成立的是
x﹣6>y﹣6
3x>3y
﹣2x<﹣2y
﹣3x+6>﹣3y+6
已知2y﹣x﹣3=0则5x﹣2y2﹣3x﹣2y+40的值是
5
45
94
﹣4
已知x﹣2y+3=0则代数式2y﹣x2﹣2x+4y﹣1的值为.
已知x﹣2y=3则代数式6﹣2x+4y的值为
0
﹣1
﹣3
3
已知点A3﹣6是正比例函数上的一点则这正比例函数的解析式是
y=﹣18x
y=2x
y=﹣2x
y=18x
已知2y﹣x=3则代数式3x﹣2y2﹣5x﹣2y﹣7的值为.
因式分解125x2﹣81y22x3﹣2x2y+xy23x4﹣18x2+81.
已知y=1是方程2-13m-y=2y的解求关于x的方程mx-3-2=m2x-5的解
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执行如图所示的程序框图若输出k的值为8则判断框内可填入的条件是
Someschoolswillhavetomakeinagreementwiththenationalsoccerreform. A.judgments B.adjustments C.comments D.achievements
“m﹣1a﹣1>0”是“logam>0”的一个
IntheUnitedStatesaloneover100millioncell﹣phonesarethrownawayeachyear.Cell﹣phonesarepartofagrowingmountainofelectronicwastelikecomputersandpersonaldigitalassistants.Theelectronicwastestreamisincreasingthreetimesfasterthantraditionalgarbageasawhole. Electronicdevicescontainvaluablemetalssuchasgoldandsilver.ASwissstudyreportedthatwhiletheweightofelectronicgoodsrepresentedbypreciousmetalswasrelativelysmallincomparisontototalwastetheconcentration含量ofgoldandotherpreciousmetalswashigherinSo﹣callede﹣wastethaninnaturallyoccurringminerals. Electronicwastesalsocontainmanypoisonousmetals.Evenwhenthemachinesarerecycledandtheharmfulmetalsremovedtherecyclingprocessofteniscarriedoutinpoorcountriesinpracticallyuncontrolledwayswhichallowmanypoisonoussubstancestoescapeintotheenvironment. Creatingproductsoutofrawmaterialscreatesmuchmorewastematerialupto100timesmorethanthematerialcontainedinthefinishedproducts.Consideragainthecell﹣phoneandimaginetheminesthatproducedthosemetalsthefactoriesneededtomaketheboxandpackaging包装itcamein.Manywastesproducedintheproducingprocessareharmfulaswell. TheU.S.EnvironmentalProtectionAgencynotesthatmostwasteisdangerousinthattheproductiondistributionanduseofproducts﹣aswellasmanagementoftheresultingwaste﹣allresultingreenhousegasrelease.Individualscanreducetheircontributionbycreatinglesswasteatthestart﹣forinstancebuyingreusableproductsandrecycling. Inmanycountriestheconceptofextendedproducerresponsibilityisbeingconsideredorhasbeenputinplaceasanincentive动机forreducingwaste.Ifproducersarerequiredtotakebackpackagingtheyusetoselltheirproductswouldtheyreducethepackaginginthefirstplace? Governments'incentivetorequireproducerstotakeresponsibilityforthepackagingtheyproduceisusuallybasedonmoney.Whytheyaskshouldcitiesortownsberesponsibleforpayingtodealwiththebubblewrap气泡垫thatencasedyourtelevision? Fromthegovernments'pointofviewaprimarygoaloflawsrequiringextendedproducerresponsibilityistotransferboththecostsandthephysicalresponsibilityofwastemanagementfromthegovernmentandtax﹣payersbacktotheproducers. 58.BymentioningtheSwissstudytheauthorintendstotellusthat. A.theweightofe﹣goodsisrathersmall B.E﹣wastedeservestobemadegooduseof C.naturalmineralscontainmorepreciousmetals D.thepercentageofpreciousmetalsisheavyine﹣waste 59.Theresponsibilityofe﹣wastetreatmentshouldbeextended. A.fromproducerstogovernments B.fromgovernmentstoproducers C.fromindividualstodistributors D.fromdistributorstogovernments 60.Whatdoesthepassagemainlytalkabout? A.Theincreaseine﹣waste. B.Thecreationofe﹣waste. C.Theseriousnessofe﹣waste. D.Themanagementofe﹣waste.
如图所示半径为R的光滑圆环固定在竖直平面内ABCD是圆环相互垂直的两条直径CD两点与圆心O等高.一质量为m的光滑小球套在圆环上一根轻质弹簧一端连在小球上另一端固定在P点P点在圆心O的正下方处.小球从最高点A由静止开始沿逆时针方向下滑已知弹簧的原长为R弹簧始终处于弹性限度内重力加速度为g.下列说法正确的是
如图在水平地面的平板小车上放一质量m=2kg的滑块滑块与车上右侧挡板同连接水平的轻弹簧小车在水平向右的力作用下以a=1m/s2的加速度做匀加速运动运动过程中弹簧处于压缩状态弹力为1N滑块与小车保持相对静止现减小外力使小车的加速度逐渐减小到零则
ManyofthethingswenowbenefitfromwouldnotbearoundThomasEdison. A.thanksto B.regardlessof C.asidefrom D.butfor
氢原子的能级公式为En=E1n=123…其中基态能量E1=﹣13.6eV能级图如图所示.大量氢原子处于量子数为n的激发态由这些氢原子可能发出的所有光子中频率最大的光子能量为﹣0.96E1则n和可能发出的频率最小的光子能量分别为
如图固定的斜面底端有一挡板板上固定一轻弹簧弹簧原长时自由端在B点将一小滑块紧靠弹簧放置在斜面上用外力作用滑块使其静止在A点现撤去外力滑块恰能上滑至顶点C然后下滑最终停在斜面上.则
如图甲所示竖直放置的汽缸内壁光滑横截面积为S=10﹣3m2活塞的质量为m=2kg厚度不计.在AB两处设有限制装置使活塞只能在AB之间运动B下方汽缸的容积为1.0×10﹣3m3AB之间的容积为2.0×10﹣4m3外界大气压强p0=1.0×105Pa.开始时活塞停在B处缸内气体的压强为0.9p0温度为27℃现缓慢加热缸内气体直至327℃.求 1活塞刚离开B处时气体的温度t2 2缸内气体最后的压强 3在图乙中画出整个过程中的p﹣V图线.
为测定一仪表专用电池的电动势和内阻某同学设计如图甲所示的电路图. 1请以画线代表导线按图甲连接好图乙的实物图 2连好电路后闭合开关S前应将电阻箱R的阻值调到选填“最大”或“最小” 3闭合开关S后调节R记录多组电压表的示数U和电阻箱阻值R并画出﹣图象如图丙所示由此可算出电池的电动势E=V内阻r=Ω 4由于电压表内阻影响所测得的E与真实值相比选填“偏大”“偏小”或“相同”.
Schoolsshouldbelivelyplaceswhereindividualsareencouragedtototheirgreatestpotential. A.accelerate B.improve C.perform D.develop
Muchtimesittingatadeskofficeworkersaregenerallytroubledbyhealthproblems. A.beingspent B.havingspent C.spent D.spending
随着新能源轿车的普及利用电磁感应原理开发的无线充电技术得到进一步应用.如图所示由地面供电装置主要装置有线圈和电源将电能传送至轿车底部的感应装置主要装置是线圈该装置使用接收到的电能对车载电池进行充电.下列说法正确的是
如图间距为d的足够长光滑导轨PQMN平行放置所在平面与水平面夹角为θPM间接一阻值为R的电阻空间存在磁感应强度大小为B方向垂直导轨平面向上的匀强磁场.一质量为m的导体棒ab由静止沿导轨下滑经一段时间后稳定.下滑过程中棒始终与导轨垂直且保持良好接触.已知导体棒电阻为r不计导轨电阻重力加速度大小为g.求稳定后 1导体棒的速度大小v 2整个回路消耗的电功率P.
FreedomandResponsibility Freedom'schallengeintheDigitalAgeisaserioustopic.Wearefacingtodayastrangenewworldandweareallwonderingwhatwearegoingtodowithit. Some2500yearsagoGreecediscoveredfreedom.Beforethattherewasnofreedom.Thereweregreatcivilizationssplendidempiresbutnofreedomanywhere.EgyptandBabylonwerebothtyranniesoneverypowerfulmanrulingoverhelplessmasses. InGreeceinAthens雅典alittlecityinalittlecountrytherewerenohelplessmasses.AndAthenianswillinglyobeyedthewrittenlawswhichtheythemselvespassedandtheunwrittenwhichmustbeobeyediffreemenlivetogether.Theymustshoweachotherkindnessandpityandthemanyqualitieswithoutwhichlifewouldbeverypainfulunlessonechosetolivealoneinthedesert.TheAtheniansneverthoughtthatamanwasfreeifhecoulddowhathewanted.Amanwasfreeifhewasself﹣controlled.Tomakeyourselfobeywhatyouapprovedwasfreedom.Theyweresavedfromlookingattheirlivesastheirownprivateaffair.EachonefeltresponsibleforthewelfareofAthensnotbecauseitwasforcedonhimfromtheoutsidebutbecausethecitywashisprideandhissafety.Theessentialbeliefofthefirstfreegovernmentintheworldwaslibertyforallmenwhocouldcontrolthemselvesandwouldtakeresponsibilityforthestate. Butdiscoveringfreedomisnotlikediscoveringcomputers.Itcannotbediscoveredonceforall.Ifpeopledonotprizeitandworkforititwillgo.Constantwatchisitsprice.Athenschanged.Itwasachangethattookplacewithoutbeingnoticedthoughitwasoftheextremeimportanceaspiritualchangewhichaffectedthewholestate.IthadbeentheAtheniansprideandjoytogivetotheircity.Thattheycouldgetmaterialbenefitsfromherneverenteredtheirminds.Therehadtobeacompletechangeofattitudebeforetheycouldlookatthecityasanemployerwhopaidhercitizensfordoingherwork.Nowinsteadofmengivingtothestatethestatewastogivetothem.Whatthepeoplewantedwasagovernmentwhichwouldprovideacomfortablelifeforthemandwiththisastheprimaryobjectideasoffreedomandself﹣relianceandresponsibilitywereneglectedtothepointofdisappearing.Athenswasmoreandmorelookedonasacooperativebusinesspossessedofgreatwealthinwhichallcitizenshadarighttoshare. Athensreachedthepointwhenthefreedomshereallywantedwasfreedomfromresponsibility.Therecouldbeonlyoneresult.Ifmeninsistedonbeingfreefromtheburdenofself﹣dependenceandresponsibilityforthecommongoodtheywouldceasetobefree.Responsibilityisthepriceeverymanmustpayforfreedom.Itistobehadonnootherterms.AthenstheAthensofAncientGreecerefusedresponsibilityshereachedtheendoffreedomandwasnevertohaveitagain. ButtheexcellentbecomesthepermanentAristotlesaid.Athenslostfreedomforeverbutfreedomwasnotlostforeverfortheworld.AgreatAmericanJamesMadisonreferredtoThecapacity能力ofmankindforself﹣government.NodoubthehadnotanideathathewasspeakingGreek.Athenswasnotinthefarthestbackgroundofhismindbutoncemanhasagreatandgoodideaitisnevercompletelylost.TheDigitalAgecannotdestroyit.Somehowinthisorthatman'sthoughtsuchanidealivesthoughunconsideredbytheworldofaction.Onecanneverbesurethatitisnotonthepointofbreakingoutintoactiononlysurethatitwilldososometime. 65.WhatdoestheunderlinedwordtyranniesinParagraph2referto? A.Countrieswheretheirpeopleneedhelp. B.Powerfulstateswithhighercivilization. C.Splendidempireswherepeopleenjoyfreedom. D.Governmentsruledwithabsolutepower. 66.Peoplebelievinginfreedomarethosewho. A.regardtheirlifeastheirownbusiness B.seekgainsastheirprimaryobject C.behavewithinthelawsandvaluesystems D.treatotherswithkindnessandpity 67.WhatchangeinattitudetookplaceinAthens? A.TheAtheniansrefusedtotaketheirresponsibility. B.TheAtheniansnolongertookprideinthecity. C.TheAtheniansbenefitedspirituallyfromthegovernment. D.TheAthenianslookedonthegovernmentasabusiness. 68.WhatdoesthesentenceTherecouldbeonlyoneresult.inParagraph5mean? A.Athenswouldcontinuetobefree. B.Athenswouldceasetohavefreedom. C.Freedomwouldcomefromresponsibility. D.FreedomwouldstopAthensfromself﹣dependence. 69.WhydoestheauthorrefertoAristotleandMadison? A.Theauthorishopefulaboutfreedom. B.Theauthoriscautiousaboutself﹣government. C.TheauthorisskepticalofGreekcivilization. D.Theauthorisproudofman'scapacity. 70.Whatistheauthor'sunderstandingoffreedom? A.Freedomcanbemorepopularinthedigitalage. B.Freedommaycometoanendinthedigitalage. C.Freedomshouldhavepriorityoverresponsibility. D.Freedomneedstobeguaranteedbyresponsibility.
图甲为一直角三角形劈倾角∠abc=37°ab长为2Lp为ab的中点小物块从a点由静止释放沿ab滑到b时速度恰好为零小物块与appb两段斜面之间的动摩擦因数分别为μ1和μ2.现将劈顺时针旋转90°如图乙所示小物块从b由静止释放已知sin37°=0.6c0s37°=0.8最大静摩擦力等于滑动摩擦力重力加速度为g则下列说法正确的是
Itmighthavesavedmesometroubletheschedule. A.didIknow B.haveIknown C.doIknow D.hadIknown
如图所示长木板质量M=3kg放置于光滑的水平面上其左端有一大小可忽略质量为m=1kg的物块A右端放着一个质量也为m=1kg的物块B两物块与木板间的动摩擦因数均为μ=0.4AB之间的距离L=6m开始时物块与木板都处于静止状态现对物块A施加方向水平向右的恒定推力F作用取g=10m/s2. 1为使物块A与木板发生相对滑动F至少为多少 2若F=8N求物块A经过多长时间与B相撞假如碰撞过程时间极短且没有机械能损失则碰后瞬间AB的速度分别是多少
请阅读下面文字及图表并按照要求用英语写一篇150词左右的文章. [写作内容] 1.用约30个单词概述上述信息的主要内容 2.结合上述信息简要分析导致交通问题的主要原因 3.根据你的分析从社会规范rulesandregulations和个人行为两方面谈谈你得到的启示不 少于两点. [写作要求] 1.写作过程中不能直接引用原文语句 2.作文中不能出现真实姓名和学校名称 3.不必写标题. [评分标准] 内容完整语言规范语篇连贯词数适当.
火箭是靠火箭发动机喷射工质工作介质产生的反作用力向前推进的飞行器.它自身携带全部推进剂不依赖外界工质产生推力可以在稠密大气层内也可以在稠密大气层外飞行.一枚火箭升空后沿着直线离开某个星球的表面星球很大表面可视为水平面如图所示.若不计星球的自转不计空气阻力则以下轨迹图中虚线可能正确的是
抗菌肽具有热稳定性以及广谱抗细菌等特点其广泛的生物学活性显示了在医学上良好的应用前景.科研工作者将若干编码抗菌肽ABP序列按照首尾相连的方式插在质粒PLG339的布康唑抗性基因内部形成长度为4800bp1bp为一个碱基对的重组质粒PLG339﹣nABP相关过程如图1所示.已知重组质粒中每个编码ABP序列中都含有限制酶AccⅢ的一个切点基因trpA的表达产物可使细胞利用无机氮源合成色氨酸色氨酸是微生物生长必须的氨基酸.请据图回答下列问题 1质粒PLG339的基本单位是. 2若PLG339﹣nABP经限制酶AccⅢ处理后产生66bp和4140bp两种长度的DNA片段单个抗菌肽ABP最多由个氨基酸构成不考虑终止密码. 3现有大肠杆菌和酵母菌两种菌群可作为导入PLG339﹣nABP的受体细胞是理由是. 4若选定的受体细胞为trpA基因缺陷型则需采用两步法筛选含重组质粒的细胞.第一步筛选的固体培养基在营养成分上的要求是不含色氨酸第二步采用“影印法”将第一步所得菌落转移到新的培养基上进行培养该培养基中应添加.通过对照最终选出能在第一步培养基上生长而不能在第二步培养基上生长的菌落即为符合要求的成功导入重组质粒的细胞. 5在测试转基因表达产物ABP对金黄色葡萄球菌的杀菌效果时获得了如图2所示的结果据此可获得的结论是ABP抑菌效果与ABP的和金黄色葡萄球菌的有关.
Itissocoldthatyoucan'tgooutsidefullycoveredinthickclothes. A.if B.unless C.once D.when
IwasrequiredtoreadoneofBernieSiegel'sbooksincollegeandwashookedonhispositivityfromthatmomenton.Thestoriesofhisunconventional36andtheexceptionalpatientshewroteaboutwereso37tomeandhadsuchabig38onhowIsawlifefromthenon.WhoknewthatsomanyyearslaterIwouldlooktoDr.BernieandhisCDsagainto39myowncancerexperience? I'manambitious40andwhenIstartedgoingthroughchemo化疗eventhoughI'mavery41personIlostmydrivetowrite.Iwasjusttootiredandnotinthe42.Onedaywhilewaitingtogoinfor43IhadoneofDr.Bernie'sbooksinmyhand.Anotherpatient44whatIwasreadingandstruckupaconversationwithme45hehadoneofhisbookswithhimaswell.It46thatamongotherthingshewasaneighty﹣year﹣oldwriter.Hewas47apublishedauthorandhewascurrently48onanewbook. Wewouldseeeachotheratvarioustimesand49friends.SometimesheworeaduckhatandIwouldtellmyselfhewasdefinitelyan50ofDr.Bernie.Hereallyputa51onmyface.Heunfortunately52lastyearduetohiscancer53heleftadeepimpressiononmeandgavemethe54topickupmypenagain.I55tomyselfIfhecandoitthensocanI. 36.A.tastes B.ideas C.notes D.memories 37.A.amazing B.shocking C.amusing D.strange 38.A.strike B.push C.challenge D.impact 39.A.learnfrom B.goover C.getthrough D.referto 40.A.reader B.writer C.editor D.doctor 41.A.positive B.agreeable C.humorous D.honest 42.A.mood B.position C.state D.way 43.A.advice B.reference C.protection D.treatment 44.A.viewed B.knew C.noticed D.wondered 45.A.while B.because C.although D.providing 46.A.cameout B.workedout C.provedout D.turnedout 47.A.naturally B.merely C.hopefully D.actually 48.A.deciding B.investing C.working D.relying 49.A.became B.helped C.missed D.visited 50.A.patient B.operator C.fan D.publisher 51.A.sign B.smile C.mark D.mask 52.A.showedup B.setoff C.felldown D.passedaway 53.A.since B.but C.so D.for 54.A.guidance B.trust C.opportunity D.inspiration 55.A.promised B.swore C.thought D.replied
2019年1月3日“嫦娥四号”月球探测器顺利着陆在月球背面成为人类首颗软着陆月背的探测器.着陆前探测器先在距月高度约为100km的圆轨道上运行然后在A点实施变轨使运行轨道变为远月点A高度约为100km近月点P高度约为15km的椭圆轨道再在P点实施制动降落月背.下列说法正确的是
运动神经元病MND患者由于运动神经细胞受损肌肉失去神经支配逐渐萎缩四肢像被冻住一样俗称“渐冻人”.下图甲是MND患者病变部位的有关生理过程NMDA为膜上的结构下图乙中曲线1表示其体内某神经纤维受适宜刺激后膜内Na+含量变化曲线Ⅱ表示膜电位变化.请据图回答问题 1兴奋在神经纤维上的传导形式是. 2据甲图判断谷氨酸是填“兴奋”或“抑制”型神经递质.图中③过程与膜的有关. 3据图分析NMDA的作用有. 4MND的发病机理是突触间隙谷氨酸过多持续作用引起Na+过度内流神经细胞内渗透压最终水肿破裂.某药物通过作用于突触来缓解病症其作用机理可能是. 5乙图中AB段Na+的跨膜运输方式是C点时神经纤维的膜电位表现为.
如图是用高电阻放电法测电容的实验电路图其原理是测出电容器在充电电压为U时所带的电荷量Q从而求出其电容C.该实验的操作步骤如下 ①按电路图接好实验电路 ②接通开关S调节电阻箱R的阻值使微安表的指针接近满刻度记下这时的电压表读数U0=6.2V和微安表读数I0=490μA ③断开电键S并同时开始计时每隔5s读一次微安表的读数i将读数记录在预先设计的表格中 ④根据表格中的12组数据以t为横坐标i为纵坐标在坐标纸上描点图中用“×”表示则 1根据图示中的描点作出图线. 2图示中i﹣t图线下所围的“面积”所表示的物理意义是. 3根据以上实验结果和图线估算当电容器两端电压为U0所带的电量Q0=并计算电容器的电容C=.这两空均保留两位有效数字
如图半径为a的内圆A是电子发射器其金属圆周表圆各处可沿纸面内的任意方向发射速率为v的电子外圆C为与A同心的金属网半径为a.不考虑静电感应及电子的重力和电子间的相互作用已知电子质量为m电量为e. 1为使电子从C射出的速率达到3vCA间应加多大的电压U 2CA间不加电压而加垂直于纸面向里的匀强磁场. ①若沿A径向射出的电子恰好不从C射出求该电子第一次回到A时在磁场中运动的时间t ②为使所有电子都不从C射出所加磁场磁感应强度B应多大.
Therealreasonwhypricesandstillaretoohighiscomplexandnoshortdiscussioncansatisfactorilyexplainthisproblem. A.Were B.willbe C.havebeen D.hadbeen
如图理想变压器原线圈接在电压不变的交流电源上.灯泡L1和L2阻值不变R是定值电阻.同时闭合开关S1S2两灯泡均能正常发光.现断开S1则
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