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“嫦娥四号”绕月探月卫星首次实现了地球和月球背面的测控通信.若把“嫦娥四号”卫星绕月运动视为仅在月球引力作用下的匀速圆周运动,设圆周轨道半径为r,月球的质量为M,“嫦娥四号”卫星的质量为m,万有引力...
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中国国防科工局宣布中国嫦娥四号将于2018年发射.下列关于嫦娥四号探月卫星所担负的任务中属于化学研究
开展月球地质特征调查
深空测控通信与遥控技术
月球背面着陆
月球表面矿物的组成和化学成分探测
2019年1月3日10时26分嫦娥四号探测器成功着陆月球背面预选着陆区并通过鹊桥中继星传回了月背影像
实现了人类探测器首次月背软着陆
开启了我国太空站建设的序幕
实现了首次月背与地球的中继通信
开启了人类月球探测新篇章
嫦娥四号任务已经通过探月工程重大专项领导小组审议正式开始实施预计发射任务将首次实现人类探测器月球背面
2016年
2017年
2018年
2019年
今年1月3日嫦娥四号月球探测器实现了人类首次在月球背面登陆.中继卫星鹊桥号用为嫦娥四号提供地月通信
探月工程嫦娥四号探测器成功发射 人民日报北京12月8日电冯华蔡金曼记者从国防科工局国家航天局
10分嫦娥一号探月卫星与稍早日本的月亮女神号探月卫星不同嫦娥一号卫星是在绕月极地轨道上运动的加上月球
嫦娥四号专家称四号星计划在2017年发射升空它是嫦娥探月工程计划中嫦娥系列的第四颗人造探月卫星主要
月球的第一宇宙速度为
嫦娥四号绕月运行的速度为
万有引力常量可表示为
嫦娥四号必须减速运动才能返回地球
据报道2018年5月21日5时28分我国在西昌卫星发射中心用长征四号丙运载火箭成功将探月工程嫦娥四号
运行的周期比月球大
向心加速度比月球大
线速度比月球小
所受合外力比月球大
我国继嫦娥三号之后将于2018年发射嫦娥四号它将首次探秘月球背面实现人类航天器在月球背面的首次着陆
中继卫星的周期为一年
中继卫星做圆周运动的向心力仅由地球提供
中继卫星的线速度小于月球运动的线速度
中继卫星的加速度大于月球运动的加速度
嫦娥一号探月卫星与稍早前日本的月亮女神号探月卫星不同嫦娥一号卫星是在绕月球极地轨道上运动加上月球的自
任务已经通过探月工程重大专项领导小组审议正式开始实施预计2018年发射任务将首次实现人类探测器月球背
天宫二号
神舟八号
嫦娥四号
玉兔三号
2019年1月3日嫦娥四号成功登陆月球背面首次实现月球背面着陆.当嫦娥四号从空中下降时说嫦娥四号是
嫦娥四号
月球表面
嫦娥四号上的照相机
嫦娥四号上的计算机
嫦娥一号探月卫星以圆形轨道绕月飞行卫星将获取的信息以微波信号发回地球假设卫星绕月的轨道平面与地月连心
嫦娥四号专家称为四号星计划在2017年发射升空它是嫦娥探月工程计划中嫦娥系列的第四颗人造探月卫星主要
月球的第一宇宙速度为
“嫦娥四号”绕月运行的速度为
月球的平均密度为ρ=
“嫦娥四号”必须减速运动才能返回地球
我国将用嫦娥四号搭载着月面微型生态圈在月球种土豆实现人类首次在月球表面开展生物学实验若嫦娥四号实现软
探月热方兴未艾我国研制的月球卫星嫦娥一号嫦娥二号均已发射升空嫦娥三号于2013年发射升空假设嫦娥三号
月球表面的重力加速度为
月球与地球的质量之比为
月球卫星与地球卫星分别绕月球表面附近与地球表面附近运行的速度之比为
“嫦娥三号”环绕月球表面附近做匀速圆周运动的周期为
2019年1月3日嫦娥四号探测器在月球背面成功着陆并与玉兔二号巡视器顺利分离实现了多个国际首次对此下
首次进行了月基低频射电天文观测
首次在月球背面软着陆和巡视探测
首次实测了月球表面浅层月壤温度
首次实现地球和月球背面的中继通信
嫦娥一号探月卫星与此前日本发射的月亮女神号探月卫星不同嫦娥一号卫星利用CCD相机对月球背面进行成像探
2007年10月我国发射了绕月运行探月卫星嫦娥1号该卫星的轨道是圆形的若已知绕月球运动的周期T.及月
嫦娥三号探月卫星于2013年12月2日1点30分在西昌卫星发射中心发射并成功实现了落月若已知引力常量
求出地球的密度
求出“嫦娥三号”探月卫星的质量
求出地球与月球之间的万有引力
得出
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Howtohelpawheelchairuserintoachair Ifyou'relookingaftersomeonewhousesawheelchairknowingthecorrectwaytoassisthiminDtoandoutofhischaircanbequiteimportant.1Soit'snecessarytounderstandhowtolendahandsafelybeforeyouattempttodoso. 1.Preparethechair. It'scrucialtoensurethatthechairisreadyforthepersontositinbeforeyoubegintomovehim.Nevertrytoadjustthechairwhenyou'realreadybearingaperson'sweight.Insteadensurethatthechairisintherightpositionbeforeyoustart.2 2.Liftsafely. Beforeyoucanhelpawheelchairuserintoachairyouneedtobeawareofseveralfactorsaswellasthecorrectwaytoliftthechairuser.Makesureyouknowhowheavyyourfriendorfamilymemberisandthatyou'restrongenoughtolifthimtositsafelyinthechair.3Yourclothingandfootwearisalsoimportant.Ensurethereisnothingyou'rewearingthatcouldcatchandthatyourshoesallowcompletestability. 3.4 Loweryourfriendorfamilymemberintothewheelchairslowlyandsteadilymakingsuretheyarefullyseatedinthechair.Iftheyareabletostandandlowerthemselvesintothechairstandbehinditandholdontothehandlestomakesureitdoesn'tmove.5Beforemovingthewheelchairaskthemtoplacetheirhandsintheirlapormoreimportantlyawayfromthewheelssothattheycanfeelcomfortable. Aboveallcheckthatthepersonyouareassistingiscalmandrelaxedandhappytoreceivehelp. A.Makethemcomfortable. B.Rememberloleavethewheelchairbehind. C.Youshouldheinanareawithnoobstaclesintheway. D.Makesureyoucanhaveafreetalkwiththewheelchairuser. E.Notknowingtherighttechniquescanresultininjurytothewheelchairuser. F.Oncetheyareseatedswingthefootrestsbackintoplacemindingtheirlegs. G.Mostimportantlymakesurethewheelchairbrakesareonandthatthechairistotallystable.
在三棱柱ABC﹣A1B1C1中AC=BC=2∠ACB=120°D为A1B1的中点. 1证明A1C∥平面BC1D 2若A1A=A1C点A1在平面ABC的射影在AC上且BC与平面BC1D所成角的正弦值为求三棱柱ABC﹣A1B1C1的高.
在数列{an}中a2=5a5=2且2an+1﹣an+2=ann∈N*则|a1|+|a2|+……+|a10|的值是
已知函数fx=则flog25=
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设全集U=R集合A={x|log2x≤1}B={x|x2+x﹣2≥0}则A∩∁UB=
若xy满足则z=y﹣2x的最大值为
PizzaisaprettycommontreatbutwherediditstartHerearethreethingsyouprobablydon'tknowaboutpizza. 1Pizza'sOriginsAreHalf﹣Baked. TheNeapolitansinItalyareproudofsayingtheyinventedpizzabutit'sprobablymoreaccuratetosaytheyperfectedit.Theideaofputtingtoppingsonaflatbreadandbakingitstartedinthe6thcenturyB.C.ButthepeopleofNapleswerethefirsttoputthetomatoonaflatbreadinthe16thcentury.Fromitsstartpizzawasthefoodforthepoorasitwascheapfillingandeasytoeatontherun.InItalianthewordpizzareferstoanythingthatismadeandthenpressedflat. 2PizzaMargheritaIsNotExactlyaSymbolofItaly. Itissaidthatonedayin1889alocalbakernamedRaffaeleEspositocreatedthreepizzasforQueenMargheritawhenshewasonatourofItaly.ThequeenlovedtheversionthathadthetomatobasilandmozzarellacheeseanditjusthappenedtomatchthecolorsoftheItalianflag.SoEspositonamedthepizzaafterher. ButScottWienerpointsoutthatItalywasunifiedinnameonlyin1889soitwasunlikelyanyNeapolitanbakerwouldwanttocelebratetheNorthernconquerorFurthertheletterofgratitudeforthepizzafromtheroyalhouseholdthatPizzeriaBrandidisplaysappearstobeafakeandmayjusthavebeenamarketingstrategy. 3HawaiianPizzaInventedbyaCanadian. SamPanopoulosfromGreeceoriginallymovedtoCanadaattheageof20.In1962hedecidedtoputsomehamandpineappleonapizzaatoneofhisrestaurantsinOntario. WejustdiditforfuntoseehowitwasgoingtotastehetoldtheBBCin2017.PanopoulosnamedittheHawaiianpizzaafterthebrandofthecannedpineappleheused.Themixtureofsweetandsavorytoppingsbecamepopularwithacertainpartofthepizza﹣lovingpublic.Theinventordiedin2017. 1Whowaspizzafirstmadefor A.Peoplewhowereverybusy. B.Peoplewhowererunningaway. C.Thepoorpeoplewhocouldaffordit. D.Soldiers. 2WhatisPizzeriaBrandi'spurposeofdisplayingtheletter A.ToshowhonorforQueenMargherita. B.Tohatchamarketingplot. C.Toprovethepizza'srelationwiththeroyalfamily. D.TotelltheworldPizzaMargheritaisexactlyasymbolofItaly. 3ThenameoftheHawaiianpizzacamefrom. A.anotherbrandoffood B.aCanadianrestaurant C.thefounder'sowninterest D.itsuniqueHawaiianflavor
数列{an}的前n项和为Sn且Sn=3n﹣1n∈N*. 1求数列{an}的通项an 2求数列{2n﹣1an}的前n项和Tn
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若抛物线x2=2pyp>0在点12处的切线也与圆x2+y2﹣2x+2y+2﹣a=0相切则实数a的值为.
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已知fxgx都是定义在R上的函数gx≠0f′xgx>fxg′x且fx=ax•gxa>0且a≠1若数列的前n项和大于62则n的最小值为
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WhenIwasfiveyearsoldmymothersufferedfromdepression﹣andotherhealthissuesleavingmetocareforher.This1reversedourrolesaschildandcaretaker. WhileIknewmymotherwassickI2thateverythingwouldbeokay.3in1997everythingwenthorribly4andmylifechangedforever. Adoptionisan5wordtoafive﹣year﹣oldbutwhenI6thatmymotherhadsignedmeovertostrangersIfeltitwastheultimatebetrayal.Isufferedfromshock7andconfusionasIattemptedto8mynewfamily.IdidlearntolovemynewparentsthoughIcouldn'tforgivemymotherfor9me.Hearingpeopletellmethatshediditinmybestinterest﹣thatsheactually10me﹣mademebitter.Iinsistedthat11shehadtrullylovedmsshewouldhavemadeitworkforourlittlefamily. HowevertheolderIgotthemoreIbegantounderstandhow12oursituationhadbeen.Wehadbeen13boxesofnoodlesandweevenlivedinourcar.Ihavestartedtounderstandthe14sheputmeupforadoptionandthatshereallydidsaveme. OnlyrecentlyhaveIbegunto15howamothercouldgiveherchildtostrangersandIrealizenowwhatasacrificeitmusthavebeenforhertoletmego.Shewas16buteveninherstatesheunderstoodthatshewaspullingmedownwithher.Shelovedme17anythingsoshewantedmetohaveachanceinlifeonesherealisedshecouldnolonger18me.WhenIlookbacknowIam19toher.EventhoughIresented怨恨herforalongtimeInowknowmylifehasbeenaspecilagiftonlybecauseshewas20enoughtogivemeup. 1A.trend B.direction C.situation D.operation 2Arecognized B.believed Cadmitted D.explained 3A.However B.Therefore C.Otherwise D.Besides 4A.well B.wrong C.mad D.common 5A.exact B.right C.warm D.foreign 6A.regretted B.wondered C.realized D.expected 7A.cold B.hunger C.tiredness D.anger 8A.giveup B.worryabout C.adjustto D.searchfor 9A.rejecting B.raising C.criticizing D.accompanying 10A.blamed B.loved Cfeared D.forgot 11A.although B.if C.since D.unless 12A.familiar B.simple C.desperate D.stable 13A.throwingaway B.chargingfor C.dreamingof D.survivingon 14A.reasons B.risks C.rules D.results 15A.remember B.understand C.ignore D.describe 16A.upset B.sick C.polite D.calm 17A.otherthan B.ratherthan C.morethan D.lessthan 18A.lend B.control C.teach D.offer 19A.grateful B.similar C.equal D.rude 20A.curious B.patient C.selfless D.careful
已知函数fx=|x﹣3|. 1若ft+f2t<9求t的取值范围 2若存在x∈[24]使得f2x+|x+a|≤3成立求a的取值范围.
ThereisarestaurantinmyMainetownthathasdonelittletoupdateitselfoverthepast80years.Thisispartofitscharmasisthewoodenphonebooththatsitsneglectedintheageofthecellphone.Ahthephonebooth.Weneeditnowmorethanever. Formeitsymbolizesthatphonecallswereonceprivateaffairseveniftheinformationbeingsharedwasnotsensitiveinanyway.Itwassimplyassumedthataphonecenversationwasmeantfortwopeopleandtwopeopleonly. Growingupinthe1960swehadonlyphoneinthehouse.AsakidIdidn'tgetormakemanycallsbecauseallmyfriendsfivewithinearshotandIcouldjustyelloutthewindowifIwantedtheirattention.IdohoweverrememberansweringthephoneaskingfortheidentityofthecallerandthenhandingthephonetomymomShe'dtakeitsayHelloMrs…onemomentpleaseandthenassheplacedherhandoverthereceiversheturnedtomeanddirectedThisisforme.Whydon'tyougooutsideandplay Flashforwardtowhatcellphoneshavedonetoourlife.Withinthespaceofafewyearsoverhearingprivateconversationsseemstobenormal.NotlongagoIwassittinginBoston'sSouthStationnearamanwhowasonhiscellphonewaitingformytrain. ThefollowingiswhatthemanhadtosayYesthat'sright.Theredandyellowroses.Thenhecontinuedtorecitehiscardnumberaridexpirationdate有效期.Istaredatthefellow.HeglancedatmeandaskedWhatMyresponsewasimmediateIrecitedhiscardnumberbacktohimalongwiththeexpirationdate. Thereisnolongerasenseofpersonalbordersorlimits.Thecellphonehasbecomeamegaphone扩音器andIhavebeenprivy私下知情todetailsofpeople'slivesthatIwouldrathernotknow.Maybephoneboothscouldserveascellphoneharborstoday. 1WhatfeaturedoestherestaurantinMainetownhave A.Itisverypopular B.Itisold﹣fashioned C.Itwillclosedown D.Ithasbeenneglected 2Asakidtheauthor A.hadafewfriends B.oftencalledhisfriends C.wasnotallowedtoanswerthephone D.learnedthatphoneconversationsareprivate 3Whatistheauthor'sattitudetowardscellphone A.Critical B.Tolerate C.Optimistic D.Approving 4WhatdidtheauthordoinBoston'sSouthStation A.Hetalkedtoanoldfriend. B.Heboughtsomecolorfulroses. C.Heoverheardaman'spersonalinformation. D.Hehelpedastrangerwhowasmakingacall.
Theaye﹣ayeinthesamefamilyaspeoplemonkeysandapesisabout40cmlongwithabushytaleaboutthesamelengthasthebody.Thedarkbrownfurislongandwoollygivingtheanimalarathershaggy蓬松的appearance.TheyarefoundonlyonMadagascaranislandoffthecoastofAfrica.ItlivesinthetropicalforestsintheeastandnorthofMadagascar. Theaye﹣ayeismostlyarboreal栖息在树上的butissometimesseenwalkingontheground.It'sactiveduringthenightlookingaroundinthetreesforfood.Theaye﹣ayeisactuallythelargestprimate灵长类动物activeduringthenight.Largeeyeshelptheaye﹣ayefinditswayaboutatnight.Duringthedaytheaye﹣ayesleepsinanestinatree.Aye﹣ayesspendalmostthewholenighttravellingaboutandfeeding. Aye﹣ayeslivealone.Sometimespairsareseenbutbasicallylittleisknownabouttheirlives.Theydon'tleapandclingtotreeslikeotherprimates.Theymoveaboutonallfourlegs.Theyoccasionallymakebriefcriesbutareusuallysilent.Wormsinsidedeadwoodformthelargestpartoftheaye﹣ayediet.Theaye﹣ayealsofeedsonfruiteggsandbambooshoots. Thefrontfeetoftheaye﹣ayeareunique.Allthetoesarelongandthinbutthethirdisexceptionallylong.Theaye﹣ayetapsonthetreetrunkandlistensformovementasitsearchesforplaceswherewormsmightbelocated.Itbitesatthetreetomakehomesthenitusesitslongthirdfingertoreachinsideandhookoutworms.Thefrontteethoftheaye﹣ayegrowcontinuouslyandareworndownbyitseatingatbarkinitssearchforworms. Aye﹣ayesareclosetobegoneortotallygone.Becauseofdeforestation伐木orforestdestructiontheanimalshavethereforebeenforcedtoeatvillagers'cropsandmanyaye﹣ayeshavebeenkilledwhiledoingso.InadditionsomepeopleonMadagascarwillbelievethatseeinganaye﹣ayeisasignthatsomeoneclosetothemwilldiesotheykilltheanimalsonsight. 1Accordingtothefirstparagraphtheaye﹣aye. A.lookscolorful. B.hasahairlesstail. C.likesthehotplaces. D.soundslikemonkeys. 2Theaye﹣aye'sthirdfingerismainlyto. A.makeholesbigenough B.reachintotheholeforfood C.helpwalkfastontheground D.gettheanimalstofixonthetree 3Whatarereducingthenumberofaye﹣ayes A.People'sactivities. B.Environmentchanges. C.Globalwarming. D.Environmentalprotection. 4Whatisthepurposeofthepassage A.Toprotecttheaye﹣ayes. B.Tostopforestsbeingdestroyed. C.Tomaketheaye﹣ayeslivebetter. D.Tointroducetheaye﹣ayes.
已知函数fx=xlnx﹣axa∈R. 1求函数fx的单调区间 2若fx+a≥0恒成立求a的值.
Indonesiaishometofouroftheworld'sworstpollutedriversandrankssecondwhenitcomestoplasticwaste.Sincesingle﹣usepackagingisalargecontributortotheproblemEvowareanIndonesian﹣basedcompanydecidedtohandlethatissuefirst.Andnowakindofedible可食用的packetshasbeeninvented. Afterinvestigatingvariousmaterialoptionsthecompanysettledonseaweed.Unlikecomcommonlyusedforcontainersseaweeddoesnotrequireresourceslikewaterorlargeamountsofspace.AccordingtoEvowareasmuchas40tonsofseaweedcanbegrowninanareathesizeofabaseballfield.Italsohelpsabsorbharmfulgreenhousegaseslikecarbondioxide.SinceIndonesianfarmersalreadyharvestmoreseaweedthantheycansellitiseasyforthecompanytofindthematerial. ThoughtheywillnotmakepublictheirproductionprocessEvowareannouncestheseaweedpackagingcontainsnochemicalsandissafetoconsume.Inadditiontowrappingfastfooditemsitcanalsobeusedtohousethingslikeinstantnoodleseasoning调味品andinstantcoffee. Thoughtheediblewrappersmaynothaveanytastethesamecannotbesaidaboutthesingle﹣usecupsthatthecompanyhasalsoinvented.Thesingle﹣usecupsthatcanbeusedtoservecolddrinksareavailablewiththetasteoforangeandgreentea. Whilereplacingplasticwiththeseaweedproductsmayseemlikeano﹣brainertomostofusitisahard﹣sellinIndonesia.AccordingtoChristianTheawarenessunderstandingandsenseofurgencytominimizetheuseofsingle﹣useplasticarestillverylow.Alsoafactoristhecostwhichishigherthanusingplastic. HopefullyEvowarewillsucceedinconvincingIndonesiansandpeopleworldwidethatswitchingtotheirproductswillgoalongwayinprotectingourbeautifulplanet. 1WhatisEvoware'spurposeofinventingeatablepackages A.Tomakefulluseofseaweed. B.Tomakegenerousprofits. C.Toattractmorecustomers. D.Toreduceplasticpollution. 2Whatcanwelearnaboutseaweedfromparagraph2 A.Itiseasytoget. B.Itbreaksdowneasily. C.Itishardtoharvest. D.Itcangrowinabaseballfield. 3Howaresingle﹣usecupsdifferentfromseaweedpackaging A.Theyarebeautiful. B.Theyhavedifferenttastes. C.Theyareinvariousshapes. D.Theyareenvironmentallyfriendly. 4Whatstopstheseaweedproductsbeingwidelyused A.Thehighcost. B.Theterribletaste. C.Thelackofseaweed. D.Thecomplexproductionprocess.
TheearthhaschangedoverandoveragainthroughoutthecourseofitshistoryInordertosurviveinchangingenvironmentsspeciesmustoftengothroughaprocessofadaptation.Adaptationreferstogeneticchangethatenablesanorganism生物体suchasananimalorplanttosurviveinitsenvironment.Iftheorganismsofaspeciescannotchangealongwiththeareainwhichtheylivetheyriskdyingout.Recenthistoryhasgivenusanimportantexampleofhoworganismsareabletosurviveoncetheirenvironmentschange. Lightgraypepperedmoths胡椒蛾anddark﹣coloredpepperedmothslivedinthecountrysidebetweenthecitiesofManchesterandLondoninEnglandManyyearsbeforethe19thcenturymoreofthelightgraypepperedmothshadbeenabletosurviveintheirenvironmentmostlybecauseoftheircolor.Birdscouldn'tseethelight﹣coloredmothsonthetreesbecausethecolorofthemothswassimilartothecolorofthetrees. Intheearly19thcenturythoughEnglandbeganthefirstyearsofitsIndustrialRevolution.Manyareasbecameoccupiedbyagrowingnumberoffactories.Manyofthesefactoriesneededcoaltoprovideenergyfortheirmachines.Whencoalbumsitgivesoffalotofdark﹣coloredsmokes.Thetreesbegantoblackenbecauseofallthesmokeintheairfromthefactories.Thismadethelightgraypepperedmothsmuchmorevulnerable.Birdscouldseethemonthetreesmoredearlyandeasilyhuntthemdown. SometimeinthenexthundredyearsscientistsbegantonoticeahugechangeinthemothpopulationlivinginandbetweenthecitiesofManchesterandLondon.Mostofthepepperedmothswereofthedark﹣coloredkind!Whatcausedthischangewasthefactthatbirdshadeatenalotofthelightgraypepperedmothsbecausethemothscouldbeseenclearlyonthedarkenedtrees.Thedark﹣coloredpepperedmothsintheareasurvivedmuchmoreeasilyandmatedwithotherdark﹣coloredpepperedmothsuntilmostofthepopulationofpepperedmothsbecamedark﹣colored. 32.Ifaspeciescan'tadapttothechangingenvironmenttheyarelikelyto. A.bedrivenoutoftheirhabitat. B.becomeextinct C.movetoanotherenvironment D.gothroughgeneticchanges 33.Whatconclusioncanbedrawnfromthechangeintwokindsofmoths A.Therewerepreviouslynodark﹣coloredpepperedmoths. B.Thelight﹣coloredpepperedmothsmovedtoanewenvironment. C.Thecolorchangehadnothingtodowiththechangeintheirenvironment. D.Darkcoloringwasbetterforthepepperedmothssurvivalinthe19thcentury. 34.Whatdoestheunderlinedwordvulnerableprobablymean A.Quicktochange B.Opentoattack C.Easilydefended D.Inastrongposition 35.Whatdoestheauthormainlydescribeinthepassage A.HowtheIndustrialRevolutionimprovedthelivesofworkers. B.Howtheearthchangedthroughoutthecourseofitshistory. C.Howhumaninfluenceorganismsthroughartificialselection. D.Hownaturalselectionchangedthepopulationofpepperedmoths.
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