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先化简再求值其中.
化简tan70°cos10°tan20°－1.
化简.
化简逻辑代数的方法有代数化简法和化简法
化简﹣1÷.
已知a+b=ab=1化简a﹣2b﹣2的结果是.
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化简再求值其中
化简求值
化简计算
化简
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数a在数轴上的位置如图所示式子|a﹣1|﹣|a|的化简结果是__________.
先化简再求值其中
先化简再求值其中.
先化简再求值其中.
化简的结果应为
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tan20°
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先化简再求值其中.
化简＝.
化简每小题5分共20分1
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图中游标卡尺和螺旋测微器的读数分别为mm和mm．
学习物理除了知识的学习外还要领悟并掌握处理物理问题的思想与方法．下列关于物理学中的思想方法叙述正确的是
Ofthethreemajordrinksoftheworld﹣teacoffeeandcocoa﹣teaisconsumedbythe1largenumberofpeople. Chinaisthehomelandoftea.Humancultivationofteaplantsdatesbacktotwothousandyearsago.TeafromChinaalong2hersilkandporcelainbegantobeknowntotheworldmorethanathousandyearsagoandsincethenit3beanimportantChineseexport. AtpresentmorethanfortycountriesintheworldgrowteawithAsiancountries4produce90%oftheworld'stotaloutput.AllteatreesinothercountrieshavetheirorigindirectlyorindirectlyinChina.Thewordfortealeavesorteaas5drinkinmanycountriesarederivatives衍生物fromtheChinesecharactercha.TheRussianscallitcha'i6soundslikechayetealeavesasitispronouncedinnorthernChinaandtheEnglishwordteasoundssimilartothepronunciationof7itcounterpart对应物inXiamen.TheJapanesecharacterforteaiswritten8exactthesameasitisinChinesethough9pronouncewithaslightdifference.ThehabitofteadrinkingspreadtoJapaninthe6thcenturybutitwasnotintroducedtoEuropeandAmericatillthe17thand18thcenturies.Nowthenumberoftea10drinkintheworldisstillontheincrease.
下列实验方案设计合理的是
向硝酸铜硝酸银和硝酸铝的混合溶液中加入一定质量的锌粉充分反应后过滤得到滤渣和滤液．以下判断正确的是
Momwantedonlyonethingforherbirthday.Canyoufindmeanothercopyofthissong?sheaskedandhandedmeaworn﹣outcassettetape.IknewexactlywhatwasrecordedonitMyRedeemer救世主.Iheardthesongplayedatleastathousandtimeswhilegrowingup.Aftersomanyyearsthecassettetapewastoowornouttobeused.IpromisedherIwouldfindareplacement. MyRedeemerbecameMom'sfavoritesongaftermyyoungerbrotherTimwaskilledbyadrunkdriverin1973.TheonlythingthathelpedhercalmdownwasthesoulfulsoundofMyRedeemerfromthelocalradiostation. Werecordeditonacassettetapesoshecouldlistentoitanytimeshewantedbutnoneofusknewwhothesoloist独唱者was.ThesedaysIthoughtthesongwouldbeeasytofindout.IwenthomeandsearchedtheInternet.SeveralsongswiththattitlepoppedupbutnoneofthemwastheoneMomloved.Igotfrustrated. Mom'sbirthdaydrewnearandthenonedayIwasdrivinghomelisteningtoourlocalradiostation.Afamiliartunecameon.ItwasMyRedeemer!AssoonasIcouldIphonedthestation.IgotalineonthesoloistwhowascalledAlanParks.ItypedhisnameintoGoogleandfoundhishomenumberinSouthCarolina.MinuteslaterIwastellinghimhowmuchhisrecordingmeanttoMom.HeofferedtoshiptwoCDsouttomepersonally.Igavehimmyaddress. RedLionPennsylvania?hesaid.DoyouknowtheLogans?Theyareourneighbors!I'vebeenfriendswiththemfor25yearsAlansaid.They'llbeatmyconcertatYorkGospelChapelonApril17th.Wouldyouandyourmomcometoo?Wesurewould.MomwasexcitedtohearAlansingMyRedeemertoherliveinconcert﹣ontheeveningofher87thbirthday. 24.WhywasthesongMyRedeemersoimportanttotheauthor'smother? A.Itcouldcomforthersadandpainfulmood. B.Itremindedherofthelovefromherhusband. C.Itwasgiventoherbyaveryimportantfriend. D.Itwastheonlythingthattheauthor'sbrotherlefther. 25.WhatdoestheunderlinedpartgotalineoninParagraph3mean? A.Talkedhappilywith. B.Thoughtalotabout. C.Maderequestof. D.Gotinformationabout. 26.WhatcanwelearnaboutAlanParksfromthispassage? A.HelivedinRedLionPennsylvania. B.Heisakindandwarm﹣heartedmusician. C.Heofferedtogivetheauthortwocassettetapes. D.Hewouldsingfortheauthor'smomontheradiostation. 27.Whichofthefollowingismostsurprising? A.AlanParksandtheauthorlivedinthesameneighborhood. B.AlanParkshappenedtogettoknowtheauthor'smother. C.Theauthor'smotherwenttotheconcertonherbirthday. D.Theauthor'smotherbecamegoodfriendswithAlanParks.
如图所示为电动机提升重物的装置电动机线圈r＝1Ω电动机两端的电压为5V正常工作时匀速提升重物电路中的电流为1A物体A重20N不计摩擦力则下列说法正确的是
某同学现要用图甲所示的电路原理图来测定一节电池的电动势和内电阻．图中R0两端的对应电压U．实验时通过改变电阻箱的阻值从而得到R0两端的不同电压实验中记录下不同的电阻R的阻值和本次实验中电压表的读数．实验后已将实验数据描在了图乙所示的﹣R+r坐标系中．已知R0＝150Ω请完成以下数据分析和处理． 1请根据原理图将图丙中的实物图连接好． 2在图乙中画出﹣R+r关系图线 3由此可得电池电动势E0＝V．结果保留两位有效数字
假如你是李华你的英国朋友Edward正在学习汉语希望你推荐一个适合他学习汉语的网站.请你根据以下内容给他回复邮件. 推荐网站www.edchinese.com 网站内容 1.网络课程中文情景对话中国风俗成语 2.其它中文电影中文歌曲唐诗等 3.有在线教师答疑解惑. 费用全部免费 注意1.词数100左右 2.可以适当增加细节以使行文连贯. .
Asimplegesturecanbeformedintoachild'smemorysoquicklythatitwillcausethechildtogiveafalseanswertoaquestionaccompaniedbythatgesture.Anewfindingsuggeststhatparentssocialworkerspsychologistsandlawyersshouldbecarefulwiththeirhandsaswellastheirwords. WhilememoriesofbothadultsandchildrenareeasytoreacttosuggestionthoseofchildrenareknowntobeparticularlyinfluencedsaidleadresearcherSaraBroadersofNorthwesternUniversity.Kidsareusedtolookingtoadultstotelleventsforthemandcanbemisledevenifnotintentionally. Previousresearchforexamplehasshownthatdetail﹣loadedquestionsoftencausefalseanswerswhenaskedsayDidyoudrinkjuiceatthepicnic?thechildislikelytosayyesevenifnojuicehadbeenavailable.Itisnotthatthechildisconsciouslylyingbutratherthedetailisquicklyformedintohisorhermemory. Toavoidthisproblemsocialworkershavelongbeenadvisedtoaskchildrenonlyopen﹣endedquestionssuchasWhatdidyouhaveatthepicnic?Butanopen﹣endedquestionpairedwithagesturebrieflymeaningajuiceboxistreatedlikeadetailedquestion.Thatischildrenbecomelikelytoanswerfalsely. Anditisn'tjustafewkids77%ofchildrengaveatleastonepieceoffalseinformationwhenadetailwassuggestedbyanordinarygesture.Gesturesmayalsobecomemorepopularwhentalkingwithnon﹣fluentlanguageuserssuchaslittlekidsBroaderssaidashandmovementscanimpartmeaningofunfamiliarwordsandphrases.Itcertainlyseemsreasonablethatadultswouldgesturemorewithchildren. IngeneralBroadersadvisesparentsandotheradultstotrytobeawareofyourhandswhenquestioningachildaboutanevent.Otherwiseyoumightbegettinganswersthatdon'treflectwhatactuallyhappened. 32.Accordingtothetextgestures. A.havenotanyfunctionatall B.arerarelyusedbypeople C.havecertaineffectonchildren D.areoftenusedbysocialworkers 33.WhyarekidseasytobemisledbygesturesaccordingtoSaraBroaders? A.Thesegesturesareveryattractive. B.Theirmemoriesareaffectedeasily. C.Childrenareeasytotelllies. D.thesegesturesareusedfrequently. 34.Accordingtothetextwhichofthefollowingquestionsmaycauseawrongreply? A.Whatwillyouhaveforlunch? B.DidyoucheatinthelastEnglishexamination? C.WhereareyougoingLucy? D.Didyouseeanythingelselastnight? 35.TheunderlinedwordimpartinParagraph6means. A.separate B.tellapart C.confuse D.passon.
下列是教案备课库中的一些常见实验请回答下列问题 1A实验说明燃烧的条件之一是． 2B实验操作中玻璃棒不断搅拌的目的是． 3C实验中两种物质研磨时发生反应的化学方程式是． 4D实验测定结果偏小的原因可能是．答出一点即可
如图1所示水平面上固定一倾角为α＝30°的光滑斜面斜面的底边与顶边PQ平行在斜面上有一虚线MNMN∥PQ在MN与PQ之间存在垂直斜面向上的磁场已知磁场的磁感应强度B随时间的变化规律如图2所示将矩形导线框ABCD放在斜面上且AB∥PQ从t＝0时刻起对线框施加一沿斜面向上的恒力F使线框由静止开始运动当线框到达MN时开始匀速进入磁场．已知线框的质量m＝1kg电阻R＝0.2ΩAB边长为x1＝1mBC边长为x2＝0.4mMN与PQ间的距离足够大F＝10Ng＝10m/s2．求 1矩形线框到达MN前的加速度以及在磁场中匀速运动时的速度 20﹣2.1s内矩形线框产生的焦耳热．
一同学要测水的折射率他找来一个方形容器装满水测得容器深度为h容器宽度为L他将此容器装满水紧贴容器竖直立一细杆并在细杆上系一红布条调整布条高度当在对面观察布条在水中的倒影与容器底部A点重合测出此时布条到容器上边界的高度H如图所示请你帮助该同学推导出水的折射率表达式．
EveryFebruary14peopleworldwidedemonstratetheiraffectionforfamilymembersfriendsteachersandsignificantotherswithagiftortwo.Howeverthisdisplayoflovedoesnotcomecheap.55%ofAmericanscelebrateValentine'sDayin2017byspendinganaverageof136.57dollarseach.Itisnowonderthatretailers零售商lovetheholiday. In1861RichardCadburyamanfromaBritishchocolatecompanycameupwiththeideaofpackagingchocolatesinheart﹣shapedboxesforValentine'sDay.Notsurprisinglytheywereaninstantsuccessandatraditionwasborn.TodayAmericansspendoveronebilliondollarshandingoutboxesofchocolatestotheirlovedones.Sweetheartstheheart﹣shapedcandyarealsoverypopular.Accordingtothemanufactureramajorityofthe8billionpiecesofcandymadeannuallyaresoldbetweenJanuary1andFebruary14. MassachusettsbusinesswomanEstherHowlandpopularizedValentine'sDaygreetingcardsinAmerica.OftencalledTheMotheroftheAmericanValentinetheartistwasthefirsttosellhandmadepapercardswithmessagesoflovetoretailers.Withover145millioncardsboughtintheUSandoverabillionworldwideValentine'sDayisnowoneofthebiggestbusinesschancesforgreetingcardcompanies.ItisnowonderthatthedayisoftenreferredtoasaHallmarkHoliday. Flowersarealsoverypopular.About51%ofpeoplemainlymenbuyredrosesfortheirlovedones.GiventhatValentine'sDayisverypopularforweddingproposals求婚itshouldnotcomeasasurprisethatalotofthemoneyspentonthisdayisusedtobuyfinejewelry.WithaquarterofAmericanstreatingtheirlovedonestoaromanticmealthedayisalsomuchwelcomedbyrestaurantowners. PopeGelasiusthemanwhomadeFebruary14Valentine'sDayin496ADwouldhaveneverimaginedthatthisfestivalwouldchangeintosuchanexpensivecelebration! 32.Whatdoesthefirstparagraphmainlytellus? A.PeoplebuytheirfriendsgiftsonFebruary14. B.Valentine'sDayiscelebratedeveryyear. C.Valentine'sDayisagoodtimetoshowlove. D.AlotofmoneyisspentonValentine'sDay. 33.WhichistrueaboutRichardCadbury'sidea? A.Itresultedinanewtasteofchocolate. B.Itledtothebirthofanewtradition. C.ItwasputforwardonValentine'sDay. D.Ithelpedthecompanyearnonebilliondollars. 34.Valentine'sDayisreferredtoHallmarkDaybecause. A.peoplegetgreetingcardsonthatday B.itwaspopularizedbyMissHowland C.itofferscardscompaniesbigbusinesschances D.retailshelpsendmessagesofloveonthatday 35.Whatisprobablyanecessarygiftforaweddingproposalaccordingtothepassage? A.Heart﹣shapedcandy. B.Messagesoflove. C.Aromanticmeal. D.Apieceofjewelry.
如图所示某厂生产的压力罐容积为100L27℃时内部密闭了1atm的空气．现用水泵给压力罐注入27℃的水使注水后罐内的压力变为3atm 1设注水过程中封闭空气的质量和温度都不变求注入水的体积 2实际上在注水过程中内部空气的温度略有升高请说明温度略有升高的原因．
在“粗盐中难溶性杂质的去除”的实验课上同学们制得了“白色的盐”小刚很高兴并大声地说“我制得了纯净的NaCl．”老师否定了他的说法并解释说“同学们制得的白色的盐中除了含有NaCl外还含有MgCl2CaCl2Na2SO4等可溶性杂质．”于是同学们为了得到更纯的NaCl设计了如下的实验方案 请回答下列问题 1沉淀A的化学式是． 2若将步骤④和⑤顺序颠倒会引发的后果是． 3沉淀B中除了含有CaCO3以外还含有．填化学式 4滤液乙中含有的阴离子是．填离子符号 5小刚向滤液乙中滴入几滴稀盐酸后就进行蒸发操作．丽丽马上制止并设计实验探究蒸发皿内溶液中除了NaCl以外是否还含有其他溶质．于是取少量该溶液于试管中接下来进行的操作是观察到的现象是． 由此得出该溶液中溶质成分为NaCl和Na2CO3．如果用该溶液蒸发结晶则得不到更纯的NaCl．
Most7﹣year﹣oldgirlsareplayingBarbieandjumpingrope.ThoughSailorGutzlermayhaveenjoyedthose41shewasalsoanactiveparticipantin42activitieswithherfather.Hewasapilotandhetaughther43skills.Sheactuallyusedthese44whenherfamily'stwin﹣engineplane45upsidedowninruralKentucky.They'dbeentraveling46toIllinoisincoldweatherfromaChristmasvacationinKeyWestFlorida. Sailorhadbrokenbonesbutwhenshecouldn't47herfathermothersisterorcousinafterthecrashshe48herselffromtheremainslitastickontheburningwingoftheplaneandwalked49foramilethroughthecolddarknessofthewoodedKentucky50. Sailor51thenearesthousehopingtogethelpforher52.Shetoldthewomanwhoansweredthe53thatshe'dbeeninan54andthatherparentsweredead. Thoughthetemperaturewas5℃belowzeroSailorwaswearingclothingmeantforthe 55Floridaandonlyhadononesock.56she'sasurvivor. Thoughherfatherhadbeen57sincehewas16andwasaflight58formorethan4000hoursdisasterstillstruck.Hehadmadethesameexact59manytimesbutstilltheweatherwon.60he'dtaughthisdaughterwhattodoandshedidit. 41.A.ropes B.sports C.activities D.dolls 42.A.outdoor B.social C.school D.daily 43.A.repair B.flight C.communication D.survival 44.A.skills B.tricks C.thoughts D.activities 45.A.flew B.landed C.swung D.appeared 46.A.around B.home C.abroad D.everywhere 47.A.wakeup B.strugglefor C.calloutto D.getcontactwith 48.A.hid B.supported C.pulled D.protected 49.A.fast B.steadily C.heavily D.endlessly 50.A.countryside B.tunnel C.wonderland D.desert 51.A.gotreadyfor B.wentonfor C.madeitto D.lookedforwardto 52.A.fear B.loss C.plane D.family 53.A.question B.request C.girl D.door 54.A.crash B.attack C.holiday D.dilemma 55.A.remote B.warm C.rainy D.famous 56.A.Actually B.Besides C.Finally D.Still 57.A.practicing B.flying C.studying D.fighting 58.A.agent B.planner C.steward D.instructor 59.A.decision B.trip C.mistake D.plan 60.A.Previously B.Accidentally C.Fortunately D.Amazingly
金属在生活生产中有着非常广泛的应用请回答下列问题 1根据如图的应用实例写出金属具有的物理性质．答出一点即可 2生铁和钢的性能不同原因是不同． 3铁制品易生锈为了防止自行车链条生锈常采取的措施是．地球上的金属资源有限除了防止金属锈蚀以外我们还可以通过来保护金属资源．答出一点即可
Forfamiliesonvacationaplaygroundprovidesawelcomebreak.Itcanalsoprovideaglimpseintothelocalculturefromthesetupoftheparktothewaysfamiliesinteract.Herearethedesignsthatliveuptothatchallenge. FruitandScentPlaygroundStockholm Isthereapickyeateronasteadydietofchickenfingersandcheese?PerhapsatriptoSweden'sFruitandScentPlaygroundwillchangehisorherculinary烹饪的tune.ThisplaygroundfeaturesabananaslideanorangeseesawpearhutsawatermelonjunglegymandapairofcherryswingsalldesignedbypublicartistJohanFernerStrom.Nowwhocansayyoucan'tplaywithyourfood? NishiRokugoParkTokyo LocatedbetweencentralTokyoandthecityofKawasakiNishiRokugocombinesrecycledrubbertires橡胶轮胎withtraditionalplaygroundequipment.Intotalmorethan3000tiresofdifferentsizesareusedtocreatetunnelsbridgestallsculpturesforclimbingandofcoursetireswings.There'slittleshadesoyoucanvisithereintheearlymorningorlateafternoonforthemostcomfortableweatherandbesuretowearyourplayclothes. BicentennialChildren'sParkSantiagoChile BicentennialChildren'splaygroundinMetropolitanParkwasbuilttocelebrate200yearsofChileanindependenceandimprovethelivesofSantiagocitizens.Dozensofslidesarebuiltintotheslopecreatingadesigncompletelycomplementary互为补充的ofthesurroundinglandscape.Fountainsoffersomerelieffromthesunandampleseatinggivesparentsaplacetorelax. 1WhatcanbelearnedaboutFruitandScentPlayground? A.ItislocatedinTokyoJapan. B.Itsdesignwasledbysomeartists. C.Itisaimedatbalancingpeople'sdiet. D.Itsfacilitiesaremodeledafterfruits. 2WhenvisitingNishiRokugoParkitisbetterto. A.wearthickprotectiveclothes B.avoidmomentswhenit'shot C.takeumbrellasandraincoats D.watchoutfortheequipment 3WhydoestheauthorrecommendBicentennialChildren'sPark? A.Itbecomespartofthesurroundings. B.Itwasbuilttoimprovepeople'slives. C.Itamuseskidsandhelpsparentsgetrelaxed. D.Itprovidesslidesforbothchildrenandadults.
Idon'twantkids.IknowIwouldn'tmakeforaverygoodmother.It'snotthatI'ddropthemorforgetthematthegrocerystoreoranythinglikethatbutthey'renotagoodfitformeandthelifeI'vecreatedformyself.I'dratherbeinCambodiakissingelephantsorcagedivingwithsharksinCapeTownorwanderingthestreetsofParisacitythathasbecomemysecondhomethantrappedathomedoingthemomthing. Theitchtobecomeamotherisn'tinmebuttheitchtotravelandtravelfarandoftenis. Iftheurgeisn'tthereIdon'tthinkit'sfairtolivealifeIdon'twantandhaveababybecausesomeoneelsethinksIshould.Thatwouldbeawful. Ilikechildren.TosayIlovethemwouldn'tbecompletelyaccurate.It'snotbecauseI'mamonster﹣thesamemonsterpeoplewhofeelwomenshouldhavechildrenwillcallme﹣butIsimplydon'tlovethembecauseI'mnotaroundthemmuch.VeryfewofmyfriendshavechildrenandtheoneswhodoIdon'tseemuchbecausewelltheyhavechildren. IhavetwonephewsinColoradowhomIlovetopiecesbutIdon'tseethemveryoften.Idon'tgooutthereasoftenasIprobablyshouldbecauseI'dratherbetraveling.SomepeoplemaycallthisselfishbutIcallitlivingmybestlife. WhenItalktomysisteraboutmynephewseverythingtheydoandsayisexcitingtoher.ThejoymysisterfeelsbyjustplayingwiththemintheyardisthesamejoyIfeeleverytimeIgetoffaplaneinanewcountry.I'dratherbeonthebeachesofSpaineverysummerwhileshepreferstospendherdaysathomewiththemclimbingtreesandsuch.I'mfulfilledonewaywhileshe'sfulfilledanotherway. I'mverymuchcertainthatatthispointinmylifemygreatestfulfillmentcomesintheformoftravelingandbeingfreeofkids.IcangoanywhereatanytimeIdon'thavetoputmylifeonholdforsomeoneelse.It'scompleteandtotalfreedom. 24.WhatdoestheunderlinedworditchinParagraphTwomean? A.traditionB.competenceC.planD.desire 25.Whyistheauthorregardedasamonster? A.Becauseshedoesn'tlikekids. B.Becauseshedoesn'twantchildren. C.Becauseshe'sdifferentfromherfriends. D.Becausesherarelystayswithchildren. 26.Whichislivingmybestlifeaccordingtotheauthor? A.Tostaywithherfamily. B.Toseehernephewsoften. C.Tovisitanewcountry. D.Totalkwithhersister. 27.Whatistheauthor'spurposeofwritingthepassage? A.Toexplainherchoiceoflife. B.Topersuadepeopletotravel. C.Toshareherhappinessinlife. D.Tointroduceauniquelifestyle.
Youcantellalotaboutpeoplebylookingattheirhair﹣notjustwhethertheybrushsprayorblow﹣dry.Scientistshavefoundawaytousehairtofigureoutwhereapersonisfromandwherethatpersonhasbeen.Thefindingcouldhelpsolvecrimesamongotherusefulapplications. Wateriscentraltothenewtechnique.Theliquidmakesupmorethanhalfanadulthuman'sbodyweight.Ourbodiesbreakwaterdownintohydrogen氢andoxygen.Atomsofthesetwoelementsendupinourtissuesfingernailsandhair. Butnotallwateristhesame.Hydrogenandoxygenatomscanvaryinhowmuchtheyweigh.Inthecaseofhydrogenforexampletherearethreetypesaccordingtotheirweights.Eachtypeiscalledahydrogenisotope同位素.Anddependingonwhereyoulivetapwatercontainsdifferentisotopes. Canhairrecordthisinformation?That'swhatJamesR.EhleringeranenvironmentalchemistattheUniversityofUtahwondered.Tofinditoutheandhiscolleaguescollectedhairfromhairstylistsin65citiesacrosstheUnitedStates.Eventhoughpeopledrinkalotofbottledwaterthesedaystheresearchershavefoundthatpeople'shairhasthesameisotopesasfoundinlocaltapwater.That'sprobablybecausepeopleusuallycooktheirfoodwiththelocalwater. Authoritiescannowusetheinformationtoanalyzehairsamplesfromcriminalsorcrimevictimsandnarrowtheirsearchforclues.ForexampleonehairsampleusedinEhleringer'sstudycamefromamanwhohadmovedfromSanFranciscotoSaltLakeCity.Ashishairgrewitreflectedhischangeinlocation. 1WhatdoweknowaboutthehydrogenisotopesaccordingtoParagraph3? A.Theyareclassifiedbysize. B.Eachtypeofthemdiffersinweight. C.Theycanimprovethequalityoftapwater. D.Someofthemcannotcombinewithoxygen. 2Whyisitpossibletoknowwherepeoplearefrombyanalyzingtheirhair? A.Peopleusethesamebottledwater. B.Peoplewashtheirhairindifferentways. C.People'shairisaffectedbytheweatheroftheplacestheystay. D.People'hairindicatesthetypeofwaterintheplacestheystay. 3Thelastparagraphismainlytoshow. A.howtorecognizecriminals B.howtocollecthairsamples C.theusefulnessofhairanalysis D.theprocessofEhleringer'sstudy 4Whichofthefollowingcanbethebesttitleforthepassage? A.Watercomposition B.Changeyourhair C.Hairdetectives D.Nowayout
将三个可以视为质点的物块ABC放在光滑的水平面上将一轻弹簧与物块B相连接右端与物块C接触但不连接开始整个系统处于静止状态今给物块A一向右的速度v0＝3m/s经过一段时间A与B发生碰撞碰后AB粘合在一起然后通过弹簧的作用使物块C也发生运动且最终物块C脱离弹簧已知mA＝1kgmB＝2kgmC＝3kg．求 ①整个运动过程中弹簧储存的弹性势能的最大值 ②物块ABC的最终速度．
如图所示斜面体A上的物块P用平行于斜面体的轻弹簧栓接在挡板B上在物块P上施加水平向右的推力整个系统处于静止状态下列说法正确的是
下列物质中属于氧化物的是属于盐的是．填序号 ①冰水共存物②液氧③空气④纯碱⑤硫酸⑥火碱⑦过氧化氢⑧高锰酸钾
如图所示为理想变压器．其原副线圈的匝数比为41．电压表和电流表均为理想电表原线圈接有u＝36sin100πtV的正弦交流电图中D为二极管．定值电阻R＝9Ω则下列说法正确的是
化学就在我们身边只要你注意就会发现．下列说法中错误的是
t1℃时向盛有10mL水的AB两支试管中分别加入等质量的甲乙两种可溶性固体充分溶解后观察到如图1所示的现象．请回答 1t1℃时试管中的溶液一定是饱和溶液． 2图2中表示乙物质溶解度曲线的是． 3若甲物质中混有少量的乙物质提纯甲物质可以采取的方法是 ． 4关于两支试管中的物质下列说法不正确的是． A．t1℃时试管A上层清液溶质质量分数＜试管B中溶质质量分数 B．保持温度不变向试管A中加入一定质量的水则溶液中溶质质量分数一定变大 C．若温度升高到t2℃两支试管中溶质质量分数一定相等不考虑水分蒸发 D．蒸发一定质量的水两支试管中都一定有固体析出
通过对酸碱盐知识的学习你认为下列叙述合理的是
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.每处错误仅涉及一个单词的增加删除或修改. Ms.Trumpismyhistoryteacher.Shelovesasubjectthatsheteachesandhasacompletelyknowledgeofittoo.Historycomesaliveinhisclasswherenoonetalksaboutsomethingbutthetopic.Shelikestoteachbytellingstorieswhatalwaysmakesherlessonssointerestingbuteasytounderstand.Ms.Trumpalsohasagoodknowledgeofothersubjectandoftenlinksittowhatsheteachesabout.Thebestpartaboutheristhatshe'salwaysnicetothosestudentswhoneedsmoretimetograspthesubjectencouragingthemaskquestionssothattheycanunderstandthesubjectbetter.
HowtoManageYourPhone'sDataUse Smartphonesgiveyouaccesstoawealthofinformationandmediabutmostnetworksputalimitontheamountofdatayoucanuseeachmonth.Atypicalphonecontractincludesadataallowanceofbetween500MBand10GBpermonth.1Youseeyourusagecanmountupsurprisinglyquickly﹣watchingafilmonthephoneisabout700MBinSDanhourofstreamingTVisaround500MBor60﹣140MBforthesameofradiochattingonSkypeforanhourisaround40MB.2 •IfpossiblewaituntilyoucanconnecttofreeWi﹣Fibeforeusingyourphone'sdatafeatures. •Whenyouareontheroaduseyourcar'sGPSnotyourphonetofindtheway.3ButmapsarepreloadedinaGPSmakingthisfreetouse. •4Manyofthesearefundedbyadsthatpopuponyourscreen.Everyadhastodownloadthroughyournetworkusingupyourdataallowance. •Ifyouregularlyneedtousealotofdataonyourphoneconsideradata﹣compressing压缩appsuchasOnavowww.onavo.com.5Soyouuselessofyourmonthlyallowance.Youmayhavetosubscribetosuchcompressionservicessoyou'llneedtoweighupwhetherit'sworththecost. A.Themoredatathehigherthemonthlycost. B.RemembertousefreeWi﹣Fianywhereyougo. C.Trythesetipstobettermanageyourdatause. D.Itcompressesdatabeforeitisfedtoyourphone. E.Butyoumightenduppayingmorethanexpected. F.Thephonehastodownloadmapdataasyoumove. G.Becarefulofhowmanyfreegamesyouplayonthephone.
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