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已知函数f(x)=ax﹣2lnx+2(1﹣a)+(a>0). (1)若f(x)≥0在[1,+∞)上恒成立,求实数a的取值范围; (2)证明:1+++……+>ln(2n+1)+(n∈N*).
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高三下学期数学《》真题及答案
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25分2019年元宵节LanternFestival故宫首次开放衣场旅游盛况空前假定你是李华你的朋友Jack参观了元宵故宫灯会lanternshow.现你校文学社LiteratureClub要征集役游故宫灯会经历的稿件请你写一封电子邮件邀请Jack投稿内容包括 1.稿件主题夜游故言灯会经历和感受 2.截止日期2019年3月31日 3.投稿方式邮箱20190678@qq.com 注意1.词数100左右 2.可适当增加细节以使行文连贯. DearJack Yours LiHua
8分Ifyouaskmostpeoplewhatwatertasteslikethey'llprobablytellyouthatwaterhasnotasteandtheymaygiveyouafunnylook.Butifyouwereafruitflyaskinganotherfruitflythatquestionmighthaveadifferentanswer. Toafruitflywaterhasataste.Scientistswanttoknowhowthefruitflyknowswaterbecausethisinformationmayhelpinlearninghowotheranimalsmanagetousewaterintherightway.Waterisveryimportanttolifebuttoomuchortoolittlecanbedeadlytoalivingcreature.Sobyunderstandinghowthefruitflytasteswaterresearchersmaylearnmoreaboutotherlivingthings. AccordingtothenewstudyaproteincalledPPK28makesitpossibleforaflytotastewater.Proteinsbuildcellsandtissuesfightdiseaseandcarrymessagesbetweencells.It'snotsurprisingthataproteinisresponsibleforthefruitfly'sabilitytotastewater. ThePPK28proteinispartofalargerfamilyofsimilarproteins.Oneoftheserelatedproteinsisusedbymammalsincludinghumanstotastesalt.Scientistshavenotfoundaproteinthatenableshumanstotastewater.IntheexperimentCameronandhisteamcomparednormalfruitflieswithfruitflieswhosetastecellshadhadbeendisabled.ThefruitfliesweregivenaspecialchemicalthatwouldglowwhentheflyusedthePPK28protein.Thenthescientistsledthefliestowater.WhenthenormalfliestastedthewaterthePPK28proteinlitup﹣showingthatitwasinuse.Thefruitflyinparticularissointerestingthatsomescientistsarehardatworkcreatingacompletemapofthefruitflybrain.Thismapwillshowallofafly'sneuronsandhelpscientistsunderstandhowtheneuronsworktogether. 1Howdomostpeoplefeelwhenaskedthetasteofwater? A.Disappointed B.Frightened. C.Amused D.Disgusted. 2Whydoscientistswanttounderstandhowthefruitflyknowswater? A.Todecreasethenumberofthefruitfly. B.Toknowmoreaboutothercreatures. C.Tomanagetousewatercorrectly. D.Todescribethetasteofwater. 3WhatdoweknowaboutthePPk28protein? A.Itcanmakehumanstastesalt. B.Itenablesthefruitflytotastewater. C.Thefruitflycan'tlivewithoutit. D.Thefruitflyusesittoavoidillnesses. 4Whatwillthescientistscontinuetoworkat? A.MakingthePPk28protein. B.Tellingmoreinformationaboutcells. C.Creatingmapsofhumanbrains. D.Studyingthefruitfly'sneuronsystems.
7.5分IntheU.S.stateofWashingtonaroadcalled^Interstate90^cutsthroughawildmountainousareatoreachthecityofSeattle.Forthearea'smanykindsofanimalsthebusyhighwaygreatlylimitstheirmovements.Crossing1﹣90﹣astheroadiscalled﹣isariskybutsometimesnecessaryact.Butsoonanimalswillhaveasaferchoiceforcrossingtheroad.Theywillbeabletogoaboveit. Tohelptheanimalsthestateisfinishingworkonitslargest﹣everwildlifebridge.The11﹣meter﹣tall20﹣meter﹣widestructurebeginsintheforest.Itformstwoarchesabovethehighwayoneforeachdirectionoftraffic.Workersareaddingfencingandplantstohelpguidetheanimalsacrossthebridge.Two﹣meter﹣thickwallswillhelpblocknoisefromvehiclesbelow. The1﹣90BridgeispartofagrowingnumberofwildlifecrossingsacrosstheUnitedStates.Somearefencessomeareoverlandbridgesandsomeareunderpasses.Theyallaimtokeepdriversandanimalsawayfromeachother.Collisionsbetweenanimalsanddriversarerarelydeadlytopeople.Buttheyareoftendeadlytowildlife.InCanada'sBanffNationalParkstudieshavefoundthatwildlifecrossingsreducethearea'sanimal﹣drivercollisionsby80percent. Mostofthewildlifebridgesareinwesternstates.Butexpertshavenotedmanyotherareasthathaveaneedforsuchpaths.JenWatkinswhoseorganizationhashelpedcampaignforanimalcrossingssaysftindformorecrossingsisthenumber﹣onebarrier. PattyGarvey﹣DardaoftheU.S.ForestServicehasworkedonthe1﹣90crossingfromthestartoftheproject.Shesaysthe﹩6﹣millionbridgewillonedaypayforitselfbecausethehighwaywillnothavetobefullyorpartlyclosedeachtimealargeanimalisstruck.ShesaidIfyoushutdownInterstate90youshutdowninterstatecommerce. 1WhatisthepurposeofbuildingthebridgeoverInterstate90? A.Toreducehumandeathsincrashwithwildlife. B.Topreventwildlifefrombeingstruckbyvehicles. C.Toarousepublicawarenessofwildlifeprotection. D.Toprovideasaferchoicetocrosstheriskyroad﹣ 2AccordingtoJenWatkinswhatisthebiggestchallengeincrossingconstruction? A.Findingwaystohelpguideanimalsacrossthebridge. B.Collectingmoneytobuildmorewildlifecrossings. C.Locatingareastoconstructappropriatecrossings. D.Encouragedriverstoobeytheregulationsoftraffic. 3WhatdotheunderlinedwordsinParagraph5imply? A.Thebridgewillprovetobewellworththehighprice. B.Expenseforbuildingsuchbridgeswillbereduced. C.Thebridgewillgreatlypromotetradeandcommerce. D.Livessavedthroughthebridgearedefinitelybeyondprice.
30分Cruz11andAnthony10couldn'tagreewerethebirdsoutontheiceducksorgeese?Therewasonlyonewaytofindout.Soona1Januaryeveninglastyearthetwofriends2ontothefrozenpondneartheirhomesinFrankfortIllinoistogeta3look.Firsttheythrewarockontotheiceto4itthentheysteppedonit.5theicewouldholdtheirweightAnthonytookafewstepsthen…FOOMP.Hecrashed6theseeminglyfrozensurface.TherewasnosoundnocrackhesaidIjustfellthrough7. Cruzrushedtohelphis8friend.FOOMP﹣thepond9himtoo.Theboyswereuptotheirnecksinicywaterandquicklylosing10intheirlimbs.Anychanceoftheirfreeingthemselveswas11.Cruzwassurehewasgoingtodie.Anthony'ssisterhadseenitandstartedscreamingforhelp. JohnLavinaneighbor12nearbyheardherandquicklypulledover.Seeingtheboyshegrabbedanearbybuoy救生圈withonehandkickedoffhis13andranintotheicywaterhittinghiswaythroughtheicewithhisfree14.EventuallyLavin15hiswaytoCruzandAnthonyandpulledthembacktoland.Theyweretakentothe16wheredoctorsdiscoveredthattheirfive﹣minutestayinthewaterhad17theirbodytemperaturenearlytendegrees. 18theboyshavefullyrecoveredthankstotheir19neighbor.JusttothinksaysCruz20hewasn'tthereIcouldhavedied. 1A.warm B.chilly C.rainy D.windy 2A.toured B.rushed C.ventured D.wandered 3A.casual B.actual C.better D.deeper 4A.test B.break C.hit D.see 5A.Bothered B.Persuaded C.Concerned D.Convinced 6A.through B.onto C.in D.across 7A.slowly B.apparently C.instantly D.gradually 8A.discouraged B.panicked C.frustrated D.confused 9A.drowned B.drew C.embraced D.swallowed 10A.balance B.feeling C.faith D.heart 11A.givingaway B.slippingaway C.slippingout D.givingout 12A.driving B.passing C.coming D.walking 13A.bags B.gloves C.shoes D.clothes 14A.fist B.leg C.arm D.finger 15A.felt B.broke C.swam D.made 16A.shelter B.home C.school D.hospital 17A.lowered B.raised C.lessened D.changed 18A.Unexpectedly B.Fortunately C.Naturally D.Immediately 19A.strong B.considerate C.fearless D.friendly 20A.unless B.until C.when D.if
干冰常用于人工降雨利用了干冰的性质.
化学晚会上小明表演了一个小魔术﹣﹣“矿泉水”变成“牛奶”“雪碧”和“红酒”.回答下列问题 1“矿泉水”实际是石灰水加入液体A后出现白色浑浊形似牛奶该过程发生反应的化学方程式为. 2“牛奶”中加入B有大量气泡产生变成雪碧则B物质是该过程发生的化学反应最多有个. 3C是一种紫色的溶液滴入“雪碧”中变为红色则雪碧的组成是.
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