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数列{an}满足a1＝2，an+1＝3an+2． （1）证明{an+1}是等比数列； （2）写出数列{an}的通项公式．
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高一下学期数学《》真题及答案
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2013
2012
2011
2010
已知数列{an}满足a1=2an+1=21+2ann∈N*则数列{an}的通项公式为.
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LastweekendIwentsnowshoeingwithagroupofteachersfrommyschool.1itfeltalittlestrange﹣﹣﹣abitlikewearingflippers脚蹼2youswim!lfeltquiteclumsytostartwithanditwas3toclimboverthefallentreeswiththesnowshoes4tomyfeet.HoweverIlove5andamusedtowalkinginmountainousareas6Isoongotusedtoit.Ilovedwalkingthroughtheforestandseeingallthetreescoveredin7!Attimeswalkinguphillinthesnowwashard8whentherewererocksunderneaththesnow.Oncewereachedthe9itwasworthit!Themountainwe10wascalledLeTanetanditwasl292mhigh﹣﹣﹣that'shigherthanSnowdonthetallestmountaininWales!Theskywasabitgraybuttheviewswere11.Imanagedtogetsomegreat12﹣﹣﹣andrememberedtousemynewcamera!Aftertakinglotsofphotoswestartedgoingdown.Insomewaysgoingdownthemountainwasharderthan13.Itwasverysteep陡峭anditwaseasyto14inthesnow. Atthebottomwehadahotdrinkinacabin﹣﹣﹣itwasclearly15afterafewhoursofwalkinginthecold!Beforewewent16Iattemptedsledging雪橇whichI'dnever172before!Itwasgreatfun! TobehonestI'dreally18snowshoesasanalternativetothemorewell﹣known19sports.Besidesbeingalotcheaperthanskiingit'seasiertodoandisconsideredtobealot20! 1A.Atfirst B.Byday C.Aboveall D.Bychance 2A.unless B.when C.since D.before 3A.practical B.easy C.difficult D.enjoyable 4A.designed B.reviewed C.adjusted D.attached 5A.swimming B.skiing C.hiking D.riding 6A.and B.but C.if D.so 7A.mud B.fog C.dirt D.snow 8A.especially B.normally C.directly D.perfectly 9A.bottom B.top C.valley D.beach 10A.promoted B.climbed C.protected D.ignored 11A.excellent B.common C.similar D.universal 12A.assistance B.guides C.photos D.equipment 13A.lying B.checking C.stayingup D.goingup 14A.spread B.test C.slip D.sleep 15A.needed B.displayed C.controlled D.backwards 16A.upstairs B.home C.abroad D.changed 17A.gotten B.seen C.lost D.tried 18A.suspect B.dislike C.recommend D.quit 19A.extreme B.winter C.water D.track 20A.cheaper B.safer C.firmer D.slower
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结合画图试写出下列已知点经过相应变换后的坐标点2-3绕原点旋转90°．
Theselfieisusedtodescribetheself﹣takenphotooftenfromasmartphone.Someonetakesabout10selfieseachtimehedoesandheonlyendsup1postingpostoneortwoofthose.Hepickstheonethathefeelsmakehimlookthe2bestgood.Inthatpicturehegainsconfidence.Forthatmomenteverythingbadorterriblethathashappenedtohim3isremovedremovebecausethatsmileiswhatgiveshimthe4determinationdeterminetolovehimself. Iread5apoemrecentlyandtheyoungmansaidIfIaskyou6whatyoulovetheanswerswillmostlikelyrolloffyourtongue.Youlovetoread.Youlovetowrite.Youloveyourmomyoudaughteroryourbestfriend.Howlongdoyouthinkyoucangoonandonbeforeyousay‘Ilove7myselfI'? Thatstatementhitmelikeatonofbricks.I'vestruggledwithconfidenceallmylife.Istilldo.Andin8nowayamIsayingthattakingaselfieisagateway9toconfidence.10However/Rather/Insteadtheselfiedoesdeservesomecreditforallowingindividualstoexpressthemselves.
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Don'tbringfoodtotheparty.IfyouI'lltakeitaway. A.are B.willdo C.do
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Asanyonewhofreelances做自由职业knowstherearelotsofadvantagesofworkingathomealone.Buttherearedrawbackstoolikethepotentialloneliness.Nowonderco﹣workingspacesarebecomingsopopulartheypermitself﹣employedindividualstofeelliketheyarepartofallofficeenvironmentwhilemakingthemgetsomeworkdonetoo.Butrentingaco﹣workingspacedoescostmoney. NowaSwedishprojectisaimingtochangethatbyturningpeople'sunder﹣usedhomesintotemporaryco﹣workingspacesavailabletofreelancersforfree.HofficewasstartedbyfreelancersChristoferGradinFranzenandJohlineZandraaboutayearagoinStockholmwhentheyinvitedafewpeopleintotheirhomeofficetoworktogether.ItwasagreatsuccessandtheprojecthassincespreadtoanumberofcitiesinEuropeNorthandSouthAmericaAustraliaIndiaandJapan.Anyonecansignupandoffertheirhomespaceasafreeco﹣workingspaceorgofindaHofficenearthem. OnaHofficedayeveryonearrivesandstartsworkatacertainhour.After45minuteseveryonegetsuptotakeabreakstretchdoqigongoryogafor10to15minutes.Afterwardspeoplecangatheraroundagainandre﹣statetheirintentionsandgoalsfortherestoftheworkdayasawaytomotivateeachother.Mealscanbeeatentogetheratacertainhourpotluck﹣style家常饭orbybringingyourownlunch. Thisprocesscreatesanencouragingandsupportiveworkenvironment.AssomefreelancersdescribeByworkingatHofficewegiveourselvesandeachotherthegifttospendourdaysinasocialworkingenvironmentwhereweareextremelyproductivewithoutignoringourotherhumanneeds.Wealsomakesuretogiveusandeachotherwhatweneedtofeelcalmhappyinspiredandcreativeduringtheworkingday. SoHofficeisnotjustaboutsharingspaceit'salsoaboutafreeexchangeofideas.AndperhapsthebestthingisthatHofficesarefreetouse. 1Hofficewasstartedto. A.changepeople'sattitudetowork B.encouragepeopletobemoresocial C.improvepeople'sworkingconditions D.provideaco﹣workingspaceforfree 2What'sthemainideaofParagraph3? A.HowpeoplerespondtoHoffice. B.HowaHofficedayworks. C.WhatpeopleshareatHoffice. D.WhatHofficemeanstopeople. 3Somefreelancers'descriptionsofHofficesuggestthatthey. A.benefitalotfromtheworkingstyle B.worklongerthanbefore C.expectmorepeopletojointhem D.can'tbeseparatedfromeachother 4WhatdoweknowaboutHofficeaccordingtothetext? A.Itisbecomingincreasinglypopular. B.Ithasbeenaroundforquiteafewyears. C.Ithascreatedmanynewjobopportunities. D.Itissuitableforpeoplefromallwalksoflife.
Iofteneatsomeandforlunch.A.tomato;fish B.tomatoes;fish C.tomato;fishes
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