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在锐角△ABC中,角A,B,C所对的边分别为a,b,c,已知b(1+2cosC)=2acosC+ccosA. (1)证明:a=2b. (2)若△ABC的面积S=4sinC,D为线段AB的中点,|...
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高三上学期数学《》真题及答案
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锐角△ABC中角ABC所对的边分别为abc已知 .
在△ABC中abc分别为角A.B.C所对的边且c=2bsinCⅠ试确定角B的大小Ⅱ若△ABC为锐角三
在△ABC中角A.B.C.所对的边分别为abc已知b=3c=8角A.为锐角△ABC的面积为6.1求角
在锐角三角形ABC中角A.B.所对的边分别为ab.若2asinB.=b则角A.=.
设△ABC的内角
,
,
所对的边分别为a,b,c,若bcosC.+ccosB.=asinA.,则△ABC的形状为( ) A.直角三角形B.锐角三角形 C.钝角三角形
不确定
△ABC中角
,
,
所对的边分别为a,b,c若
<cosA,则△ABC为( ) A.钝角三角形 B.直角三角形 C. 锐角三角形
等边三角形
在锐角△ABC中角ABC所对应的边分别为abc若b=2asinB则角A等于.
△ABC中角
B.C.所对的边分别为a、b、c,若
直角三角形
锐角三角形
等边三角形
在△ABC中角A.B.C.所对的边分别为abc已知b=3c=8角A.为锐角△ABC的面积为6.1求角
锐角△ABC中角ABC所对的边分别为abc已知 .
设△ABC的内角
,
,
所对的边分别为a,b,c,若bcosC+ccosB=asinA,则△ABC的形状为( ) A.锐角三角形B.直角三角形C.钝角三角形
不确定
设△ABC的内角A.B.C.所对的边分别为abc若bcosC.+ccosB.=asinA.则△ABC
在△ABC中三边abc所对的角分别为
,
,
,若a=2bcosC,则△ABC是( ) A.锐角三角形B.等腰三角形C.钝角三角形
直角三角形
△ABC中角
,
,
所对的边分别为a,b,c若
<cosA,则△ABC为( ) A.钝角三角形B.直角三角形C.锐角三角形
等边三角形
△ABC中角
B.C.所对的边分别为a、b、c,若
<cos A.,则△ABC为 A.钝角三角形
直角三角形
锐角三角形
等边三角形
在锐角△ABC中abc分别为角ABC所对的边且a=2csinA角C=.
在锐角△ABC中abc分别为角A.B.C.所对的边且a=2csinA.角C.=________.
设△ABC的内角
,
,
所对的边分别为a,b,c,若bcosC+ccosB=asinA,则△ABC的形状为( ) A.锐角三角形B.直角三角形C.钝角三角形
不确定
在锐角△ABC中角A.B.C.所对的边分别为abc已知a=b=3.Ⅰ求角A.的大小Ⅱ求△ABC的面积
在锐角△ABC中abc分别为角A.B.C.所对的边且a=2csinA则角C.=________.
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设x>0y>0若成等差数列则的最小值为
铁铜等金属及其化合物在日常生产生活中用途非常广泛. Ⅰ.实验室欲制备0.3molCuNO32晶体甲乙两同学分别设计实验方案如下 甲CuCuNO32乙CuCuOCuNO32 1从绿色化学的角度分析同学的方案更合理 2乙同学实验时通入O2的速率不宜过大为便于观察和控制产生O2的速率宜选择装置填字母序号. Ⅱ.某化学实验小组通过实验来探究一包黑色粉是否由Fe3O4CuO组成探究过程如下 1提出假设 假设1.黑色粉末是CuO 假设2.黑色粉末是Fe3O4 假设3.黑色粉末是CuO和Fe3O4的混合物. 2设计探究实验 取少量粉末放入足量稀硫酸中在所得溶液中滴加KSCN试剂. ①若假设1成立则实验现象是溶液显蓝色. ②若假设2或3成立则实验现象是. 为进一步探究继续向所得溶液加入足量铁粉若产生的现象则假设3成立. 有另一小组同学提出若混合物中CuO含量较少可能加入铁粉后实验现象不明显. 查阅资料Cu2+与足量氨水反应生成深蓝色溶液Cu2++4NH3•H2O=CuNH342++4H2O. 为探究是假设2还是假设3成立另取少量粉末加稀硫酸充分溶解后再加入足量氨水若假设2成立则产生现象若假设3成立则产生现象. Ⅲ.由Fe3O4FeOCuOFe组成的固体混合物在加热条件下用足量的CO还原得到金属混合物2.86g将生成的CO2气体用足量的澄清石灰水吸收后产生5.00g白色沉淀.固体混合物的质量是.
设函数fx=对任意x1x2∈0+∞不等式恒成立则正数k的取值范围是.
常温下对于①0.1mol/LCH3COOH溶液②pH=1的HCl溶液③pH=13的NaOH溶液④0.1mol/LCH3COONa溶液下列说法正确的是
SeeacellphonecoverthatyoulikeonTaobao?Forgetaboutplacinganorderpayingthebillonlineandwaitingfordaysforittobedeliveredtoyou.Inthenearfutureyou'llbeabletogetitinminutesjustbyhittingprintonyourcomputer.Youmightfindithardtobelievethatyoucouldactuallyprintanobjectlikeyouwouldapicture.Butitisnotthathardtounderstandhowitwouldwork.Justasatraditionalprinterspraysinkontopaperlinebylinemodern3Dprintersspreadmaterialontoasurfacelayerbylayerfromthebottomtothetopgraduallybuildingupashape. Insteadofinkthematerialsthe3Dprinterusesaremainlyplasticresin树脂andcertainmetals.Thethinnereachlayeris﹣fromamillimetretolessthanthewidthofahair﹣thesmootherandfinertheobjectwillbe.Thismaysoundlikeacompletelynewtechnologybutthetruthisthat3Dprintinghasbeenaroundsincethelate1980s.Backthenitwasbarelyaffordableformostpeoplesofewknewaboutit. Lastyearthoughsawabigchangeinthe3Dprintingindustry﹣printersbecamemuchcheaper.Forexample10yearsagoadesktop3Dprintermighthavecost£20000whilenowtheycostonlyabout£1000accordingtotheBBC.Takenoutofthefactoryandintroducedtomorediverseandcommonuses3Dprintingcancreatejustaboutanythingyoucanthinkof﹣flutesbikinisjewelryaircraftpartsandevenhumanorgans.InfactscientistsfromCornellUniversityinNewYorkhavejustmadeanartificialearusinga3DprinteraccordingtoScienceDaily.Thefakeearlooksandactsexactlylikeanaturalone. Howeveras3Dprintingbecomesmorecommonitmaybringaboutcertainproblems﹣suchaspiracy.Onceyoucandownloadacoffeemakerorprintoutanewsetofkitchenutensils餐具onyourpersonal3Dprinterwhowillvisitaretailstoreagain?anexpertin3DprintingtoldForbesNews.Evenmorefrighteningwhatifanyoneintheworldcouldusea3Dprintertoprintoutafullyfunctioninggun? 32.Accordingtothearticleinthefuturethe3Dprintingtechnologywill. A.enablepeopletomakebetterpurchasesonline B.changethewaywemakemanyproducts C.beappliedaswidelyinourdailylifeascomputers D.shortenthetimeittakesforpeopletogetwhattheybuyonline 33.Whathappenedinthe3Dprintingindustrylastyear? A.The3Dprintingtechnologywastakenoutofthefactory. B.The3Dprintingtechnologybegantobeusedinvariousfields. C.The3Dprinterwasusedformedicaltreatmentforthefirsttime. D.The3Dprinterbecamemoreaffordableforconsumers消费者. 34.Whatisthebesttitleofthepassage? A.GreatDemandfor3DPrinters B.TechnologyintheFuture C.OnlineShoppingDisappearing D.PrintingoutEverything 35.Howisthelastparagraphdeveloped? A.Bygivingexamples. B.Bymakingcomparisons. C.Byanalyzingthecauseandeffect. D.Byusingfigures.
这个游戏的独特之处在于它让孩子学会如何应对现实生活中的问题.whatWhatmakesthegameuniqueisthatithelpschildrenlearnhowtocopewith problemsinreallife..
在公差不为零的等差数列{an}中2a3﹣a72+2a11=0数列{bn}是等比数列且b7=a7则log2b6b8的值为
化学与科技社会生产生活密切相关.下列有关说法不正确的是
街头艺术家运用创意将鲜艳明亮的色彩带进了老社区.bring.
Youthsporthasthepotentialtoaccomplishthreeimportantobjectivesinchildren'sdevelopment.Firstsportprogramscanprovideyouthwithopportunitiestobephysicallyactivewhichcanleadtoimprovedphysicalhealth.Secondyouthsportprogramshavelongbeenconsideredimportanttoyouth'spsychosocialdevelopmentprovidingopportunitiestolearnimportantlifeskillssuchascooperationdisciplineleadershipandself﹣control.Thirdyouthsportprogramsarecriticalforthelearningofmotorskillsthesemotorskillsserveasafoundationforfuturenationalsportstarsandrecreationaladultsportparticipants.Whencoachersdevelopactivitiesforyouthpracticesandwhensportorganizationsdesignyouth﹣sportprogramstheymustconsidertheimplicationofdeliberateplayanddeliberatepractice. ResearchfromTelama2006statesthatregularparticipationindeliberateplayordeliberatepracticeactivitiesduringchildhoodandyouthagesninetoeighteenincreasesthelikelihoodofparticipationinsportsduringadulthoodbysixtimesforbothmalesandfemales.Côté2002definesdeliberateplayactivitiesinsportasthosedesignedtomaximizeenjoyment.Theseactivitiesareregulatedbyflexiblerulesadaptedfromstandardizedsportrulesandaresetupbythechildrenorbyaninvolvedadult.Childrentypicallychangerulestofindapointwheretheirgameissimilartotheactualsportbutstillallowsforplayattheirlevel.Forexamplechildrenmaychangesoccerandbasketballrulestosuittheirneedsandenvironmente.g.inthestreet.onaplayingfieldorinsomeone'sbackyard.Wheninvolvedindeliberateplayactivitieschildrenarelessconcernedwiththeoutcomeoftheiroutcomeoftheirbehavior.whethertheywinorlosethanwiththebehavior.havingfun. OntheotherhandEricsson1993suggeststhatthemosteffectivelearningoccursthroughinvolvementinhighlystructuredactivitiesdefinedasdeliberatepractice.Deliberatepracticeactivitiesrequireeffortproducenoimmediaterewardsandaremotivatedbythegoalofimprovingperformanceratherthanthegoalofenjoyment.Whenindividualsareinvolvedindeliberateplaytheyexperimentwithdifferentcombinationsofbehaviorsbutnotnecessarilyinthemosteffectivewaytoimproveperformance.Incontrastwhenindividualsareinvolvedindeliberatepracticetheyexhibitbehavior.focusedonimprovingperformancebythemosteffectivemeansavailable.Forexamplethebackhandskillsintenniscouldbelearnedandimprovedovertimebyplayingmatchesorbycreatingfunpracticesituations.Howeverplayerscouldmoreeffectivelyimprovetheirbackhandperformancebypracticingdrillsthatmightbeconsideredlessenjoyable.Althoughdrillsareusedinmosteffectivemeansavailablepracticemightnotbethemostenjoyabletheymightbethemostrelevanttoimprovingperformance. NoteAnswerthequestionsorcompletethestatementsinNOMORETHANTENWORDS 78.Besidesthelearningofmotorskillswhataretheothertwoimportantobjectivesofyouthsport?. 79.Ifchildrenparticipateindeliberateplayordeliberatepracticeactivitiestheyaremorelikelyto. 80.Indeliberateplayactivitieswhatdochildrendotomaximizeenjoyment?. 81.Incontrasttodeliberateplaydeliberatepracticeisaimedat.
能正确表示下列反应离子方程式的是
“a=1”是“函数y=cos2ax﹣sin2ax的最小正周期为π”的
下列有关溶液中粒子浓度关系的比较中不正确的是
在△ABC中若2=•+•+•则△ABC是
Papaasasonofadirt﹣poorfarmerleftschoolearlyandwenttoworkinafactoryforeducationwasfortherichthen.Sotheworldbecamehisschool.Withgreatinteresthereadeverythinghecouldlayhishandsonlistenedtothetowneldersandlearnedabouttheworldbeyondhistinyhometown.There'ssomuchtolearnhe'dsay.Thoughwe'rebornstupidonlythestupidremainthatway.Hewasdeterminedthatnoneofhischildrenwouldbedenied拒绝aneducation. ThusPapainsistedthatwelearnatleastonenewthingeachday.ThoughaschildrenwethoughtthiswascrazyitwouldneverhaveoccurredtoustodenyPapaarequest.Anddinnertimeseemedperfectforsharingwhatwehadlearned.Wewouldtalkaboutthenewsofthedaynomatterhowinsignificant微不足道的itwasnevertakenlightly.Papawouldlistencarefullyandwasreadywithsomecommentalwaystothepoint. Thencamethemoment﹣thetimetosharetheday'snewlearning. Papaattheheadofthetablewouldpushbackhischairandpouraglassofredwinereadytolisten. Felicehe'dsaytellmewhatyoulearnedtoday. IlearnedthatthepopulationofNepalis… Silence. Papawasthinkingaboutwhatwassaidasifthesalvation拯救oftheworldwoulddependuponit.ThepopulationofNepal.Hmm.Well…he'dsay.Getthemaplet'sseewhereNepalis.AndthewholefamilywentonasearchforNepal. Thissameexperiencewasrepeateduntileachfamilymemberhadaturn.Dinnerendedonlyafterwehadaclearunderstandingofatleasthalfadozensuchfacts. Aschildrenwethoughtverylittleabouttheseeducationalwonders.Ourfamilyhoweverwasgrowingtogethersharingexperiencesandparticipatinginoneanother'seducation.Andbylookingatuslisteningtousrespectingourinputaffirming肯定ourvaluegivingusasenseofdignity体面Papawasunquestionablyourmostinfluentialteacher. LaterduringmytrainingasafutureteacherIstudiedwithsomeofthemostfamouseducators.Theywereimparting传授whatPapahadknownallalong﹣thevalueofcontinuallearning.Histechniquehasservedmewellallmylife.NotasingledayhasbeenwastedthoughIcannevertellwhenknowingthepopulationofNepalmightproveuseful. 21.Whatdoweknowfromthefirstparagraph? A.Theauthor'sfatherwasborninaworker'sfamily. B.Thosebornstupidcouldnotchangetheirlife. C.Thetownelderswantedtolearnabouttheworld. D.Thepoorcouldhardlyaffordschooleducation. 22.Theunderlinedworditinthesecondparagraphrefersto A.onenewthing B.arequest C.thenews D.somecomment 23.Itcanbelearnedfromthepassagethattheauthor. A.enjoyedtalkingaboutnews B.knewverywellaboutNepal C.feltregretaboutthosewasteddays D.appreciatedhisfather'seducationaltechnique 24.Whatisthegreatestvalueofdinnertimetotheauthor? A.Continuallearning. B.Showingtalents. C.Familyget﹣together. D.WinningPapa'sapproval.
肼N2H4又称联氨广泛用于火箭推进剂有机合成及燃料电池NO2的二聚体N2O4则是火箭中常用氧化剂.试回答下列问题 1肼燃料电池原理如图所示左边电极上发生的电极反应式为 2火箭常用N2O4作氧化剂肼作燃料已知 N2g+2O2g=2NO2g△H=﹣67.7kJ•mol﹣1 N2H4g+O2g=N2g+2H2Og△H=﹣534.0kJ•mol﹣1 2NO2g⇌N2O4g△H=﹣52.7kJ•mol﹣1 试写出气态肼在气态四氧化二氮中燃烧生成氮气和气态水的热化学方程式. 3联氨的工业生产常用氨和次氯酸钠为原料获得也可在高锰酸钾催化下尿素[CONH22]和次氯酸钠﹣氢氧化钠溶液反应获得尿素法反应的离子方程式为. 4如图所示A是由导热材料制成的密闭容器B是一耐化学腐蚀且易于传热的透明气囊.关闭K2将各1molNO2通过K1K3分别充入AB中反应起始时AB的体积相同均为aL. ①B中可通过判断可逆反应2NO2⇌N2O4已经达到平衡. ②若平衡后在A容器中再充入0.5molN2O4则重新到达平衡后平衡混合气中NO2的体积分数填“变大”“变小”或“不变” ③若容器A中到达平衡所需时间ts达到平衡后容器内压强为起始压强的0.8倍则平均化学反应速率vNO2等于. ④若打开K2平衡后B容器的体积缩至0.4aL则打开K2之前气球B体积为L.
阅读下面短文掌握其大意从每题所给的ABCD四个选项中选出最佳选项并在答题卡上将该项涂黑. MyyoungerbrotherwouldbeleavingforcollegeandIwasleavingforanewjobinEurope.Weonlyhadafewpreciousmonthsleftasafamilylivingunderthesame41.Everythingwouldchangeinthe42. Afamilyofmagpies喜鹊43inourmapletree.Thisfamilyseemedtobeextraordinarilylively.Oneearlymorningthenoisewasso44thatmydadwentouttoseewhatthebirdsweredoing.Hefoundayoungmagpie45aroundtheyardflapping拍打hislittlewingsandyelling. DadlookedupinthetreetofindMommyandDaddyMagpiesittingonabranchandglaring46athim.Hehadtodosomethingforthepoorlittlething.Dadcalledthezoofor47.Theytoldhimnotto48itandassuredhimthebabywouldlearntoflyonitsown.Dadnolonger49themagpiearoundtheyard.Hedidhoweverwatchhim50fromthelivingroomwindowjusttomakesureacatdidn'tturnhiminto51. ThenextdayIgota52atmysummerjob.Itwasfrommyfather.Henevercalledme53.HeaskedmeifIsawMoreybeforeIlefthome﹣henamedthebirdMorey. DrivinghomefromworkI54itwasn'tonlyaboutthemagpiebutalsoabouthisownlittlefledglings幼鸟whowere55thenest.Itwasaboutmybrotherandme.DadfeltashelplessastheMommyandDaddybirdwatchinginthetree.Hecouldn'tmakeusflynorcouldhe56catsonceweleftthenest. Igothomeandfoundhimlookingoutofthekitchenwindowwith57inhiseyes.I58himbysayingMoreymighthavelearnttoflywithverygoodparentsraisinghim. SoonitwastheendofAugust.Bagswere59anditwastimeformybrotherandmetoleavethenest.IntheendDadhadnothingtoworryabout.He60hislittlefledglingswell.Andweflew… 41.A.house B.roof C.family D.room 42.A.fall B.spring C.winter D.summer 43.A.cutdown B.tookdown C.settleddown D.broughtdown 44.A.exciting B.low C.frightening D.loud 45.A.flying B.wandering C.running D.jumping 46.A.helplessly B.carefully C.hopefully D.suddenly 47.A.advice B.permission C.leave D.conclusion 48.A.hunt B.touch C.ignore D.chase 49.A.helped B.assisted C.followed D.collected 50.A.coldly B.cautiously C.purposely D.gladly 51.A.taste B.nest C.meat D.lunch 52.A.call B.message C.news D.notice 53.A.athome B.atschool C.atwork D.atnoon 54.A.summarized B.wondered C.realized D.questioned 55.A.building B.leaving C.directing D.quitting 56.A.driveaway B.fightagainst C.arguewith D.associatewith 57.A.light B.doubts C.pain D.tears 58.A.greeted B.comforted C.persuaded D.hugged 59.A.locked B.strengthened C.loaded D.packed 60.A.brought B.loved C.raised D.accompanied
某课外小组欲探究在适当温度和催化剂的条件下SO2与O2反应后混合气体的成分.已知①沸点SO2﹣10℃SO345℃②SO3遇水剧烈反应放出大量热产生酸雾.③98.3%H2SO4可以吸收SO3和酸雾. 提供的药品Na2SO3固体10mol/LH2SO4催化剂V2O5KMnO4固体蒸馏水0.5mol/LBaCl2溶液98.3%H2SO42.0mol/LNaOH溶液品红溶液等. 1该小组同学用Na2SO3固体与10mol/LH2SO4混合制取SO2.发生装置应该选用下图中装置填字母. 2若选用上图中b装置制O2反应的方程式是. 3该小组同学为检验反应后混合气体的成分设计如下装置 ①b中发生反应的化学方程式是. ②c中盛放的试剂是e中盛放的试剂是其作用是. ③某同学提出用饱和的NaHSO3溶液代替98.3%的浓H2SO4请你评价该方案是否可行若可以不必说明理由若不可行简述其理由.
设a∈则使函数y=xa的定义域是R且为奇函数的所有a的值是
若存在实常数k和b使得函数Fx和Gx对其公共定义域上的任意实数x都满足Fx≥kx+b和Gx≤kx+b恒成立则称此直线y=kx+b为Fx和Gx的“隔离直线”.已知函数fx=x2x∈Rgx=x<0hx=2elnx.有下列命题 ①Fx=fx﹣gx在x∈﹣0内单调递增 ②fx和gx之间存在“隔离直线”且b的最小值为﹣4 ③fx和gx之间存在“隔离直线”且k的取值范围是﹣40] ④fx和hx之间存在唯一的“隔离直线”y=2x﹣e. 其中真命题的个数有
学校即将举办读书节目前正广泛征集读书节宣传册图片.假设你是该校学生潘阳你已找到以下三幅图片决定给读书节组委会写一封信推荐其中一幅你的信须包括以下内容 1.简单描述你想推荐的那幅图片 2.阐述你用这幅图片宣传读书节的理由.
下列说法正确的是
已知单调递增的等比数列{an}满足a2+a3+a4=28且a3+2是a2a4的等差中项. Ⅰ求数列{an}的通项公式 Ⅱ若bn=﹣nanSn=b1+b2+…+bn对任意正整数n总有Sn+n+man+1<0成立试求实数m的取值范围.
以直角坐标系的原点O为极点x轴的正半轴为极轴且两个坐标系取相等的长度单位.已知直线l的参数方程为t为参数0<α<π曲线C的极坐标方程为ρsin2θ=4cosθ. 1求曲线C的直角坐标方程 2设直线l与曲线C相交于AB两点当α变化时求|AB|的最小值.
设NA为阿伏加德罗常数的值.下列说法正确的是
汽车尾气中CONOx以及燃煤废弃中的SO2都是大气污染物对它们的治理具有重要意义.吸收SO2和NO获得Na2S2O2和NH4NO3产品的流程图如下Ce为铈元素 1装置Ⅰ中NaOH溶液吸收SO2也可生成Na2SO3和NaHSO3的混合溶液 ①写出NaOH溶液吸收SO2生成等物质的量的Na2SO3和NaHSO3混合溶液时总反应的离子方程式 ②已知混合液pH随nSO32﹣nHSO3﹣变化关系如下表 当混合液中nSO32﹣nHSO3﹣=11时cNa+cHSO3﹣+2cSO32﹣填“>”“=”或“<” 2装置Ⅱ中酸性条件下NO被Ce4+氧化的产物主要是NO3﹣NO2﹣写出只生成NO3﹣的离子方程式 3装置Ⅲ的作用之一是再生Ce4+其原理如图所示. ①生成的Ce4+从电解槽的填字母序号口流出 ②生成S2O42﹣的电极反应式为 4已知进入装置Ⅳ的溶液中NO2﹣的浓度为ag•L﹣1要使1m3该溶液中的NO2﹣完全转化为NO3﹣至少需向装置Ⅳ中通入标准状况下的O2L.用含a代数式表示
下列实验能达到预期目的是 ①用乙醇和浓硫酸除去乙酸乙酯中的少量乙酸 ②用饱和NaCl溶液除去Cl2中的少量HCl ③用饱和NaHCO3溶液除去CO2中的少量SO2 ④用加热的方法提取NH4Cl固体中混有的少量碘 ⑤用醋和澄清石灰水验证蛋壳中含有碳酸盐 ⑥用米汤检验食用加碘盐中含碘 ⑦用纯碱溶液洗涤餐具 ⑧用玻璃棒搅拌漏斗中的液体以加快过滤的速度 ⑨加入盐酸以除去硫酸钠中的少量碳酸钠杂质
1AlN的晶体结构与单晶硅相似在AlN晶体中每个Al原子与个N原子相连与N元素同主族的元素As位于元素周期表的第四周期其基态原子的核外电子排布式为. 2A元素的原子价电子排布为ns2np2B元素的最外层电子数是其电子层数的3倍C元素原子的M电子层p亚层中有3个未成对电子D元素原子核外的M层中只有2对成对电子. ①当n=2时AB2属于分子填“极性”或“非极性”. ②若A元素的原子价电子排布为3s23p2ACD三种元素的第一电离能由大到小的顺序是用元素符号表示 3CaO晶胞如右图所示其中Ca2+的配位数为CaO晶体和NaCl晶体的离子排布方式相同CaO晶体的熔点高于NaCl晶体的熔点的主要原因是.
等比数列{an}中a1=2a8=4函数fx=xx﹣a1x﹣a2…x﹣a8则f′0=.
在等差数列{an}中2a1+3a2=112a3=a2+a6﹣4其前n项和为Sn. 1求数列{an}的通项公式 2设数列{bn}满足bn=求数列{bn}的前n项和Tn.
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