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用如图1所示的实验装置做“验证机械能守恒定律”实验时，将打点计时器固定在铁架台上，使重物带动纸带从静止开始下落 ①除了图示的实验器材，下列实验器材中还必须使用的是 （填字母代号）． A．交...
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高三下学期物理《》真题及答案
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利用如图所示的实验装置验证机械能守恒定律.关于此实验下列说法中正确的是
必须测出重物的质量
必须用秒表测出重物下落的时间
先释放纸带，再接通打点计时器电源
纸带起始端点迹模糊，也可用验验证机械能守恒
某同学利用如图所示的实验装置验证机械能守恒定律.1请指出该同学在实验操作中存在的两处明显错误或不当①
某同学用图a所示的实验装置验证机械能守恒定律已知打点计时器所用电源的频率为50Hz当地重力加速度为g
机械能守恒定律
在验证机械能守恒定律时如果以υ2/2为纵轴以h为横轴根据实验数据绘出的υ2/2-h图线应是图线的斜率
在验证机械能守恒定律的实验中1为进行验证机械能守恒定律的实验有下列器材可供选用铁架台打点计时器复写纸
以下四个实验中都要用到小球或重锤实验中必须测定小球或重锤质量的是___________选填下面正确选
验证机械能守恒定律的实验装置如图所示关于该实验下列说法正确的是
重物应选用密度小的物体
两个限位孔应在同一竖直线上
打点计时器应接低压直流电源
应先释放纸带，后接通电源
用如图7所示的实验装置验证机械能守恒定律.实验所用的电源为学生电源输出电压为6V的交流电和直流电两种
以下四个中学学生实验中都要用到小球或者重锤实验中必需测定小球或重锤质量的是选填下面正确选项前的代号字
某同学采用如图所示的实验装置做验证机械能守恒定律的实验时请指出这个实验过程中产生误差的主要原因找出两
1图甲中游标卡尺读数为▲cm图乙中螺旋测微器读数为▲mm2某同学用如图所示的实验装置验证机械能守恒定
在验证机械能守恒定律的实验中需要测量的是重物的A.质量B.下落高度C.下落时间D.瞬时速度
某校物理研究性学习小组设计了如图所示的实验装置做验证机械能守恒定律的实验.图中ab为两重物通过一光滑
某同学用图14a所示的实验装置验证机械能守恒定律.已知打点计时器所用电源的频率为50Hz当地重力加速
用如图所示的实验装置验证机械能守恒定律.实验所用电源为学生电源输出电压为6V的交流电和直流电两种.重
①验证动量守恒定律②验证机械能守恒定律③用单摆测定重力加速度A.要用打点计时器的实验是B.要用天平的
在下列四个学生分组实验中都要用到小球或垂锺其中不需要测定小球或重锤质量的实验是填字母代号A.验证机械
某同学用图a所示的实验装置验证机械能守恒定律已知打点计时器所用电源的频率为50Hz当地重力加速度为g
在利用重锤做自由落体运动验证机械能守恒定律的实验中挑选纸带的原则是①②.
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如图为速度选择器示意图P1P2为其两个极板．某带电粒子以速度v0从S1射入恰能沿虚线从S2射出．不计粒子重力下列说法正确的是
某物理兴趣小组利用如图所示的电路给一个原来不带电的电容器充电在充电过程中电路中的电流为i电容器所带的电荷量为q两极板问的电势差为u电容器储存的能量为E电．下面的四幅示意图分别表示iqu和E电随时间t的变化关系其中可能正确的是
DT WhenBarbraStreisanddiscoveredin2003thataphotographofherCaliforniabeachhousewasamong12000photosontheInternetaspartofacollectionbyphotographerKennethAdelmanshedidwhatanyfamouspersonwoulddohithimwitha﹩50millionlawsuit.Butintryingtoholdbacktheimagesshecausedadifferentoutcome.Herlegalactionsledtoalmosthalfamillionpeoplevisitingthewebsiteviewingandcopyingthephotoswithinamonth. EversincethentheeffectoflettingpublicknowsomethingyouaretryingtokeepsecrethasbeencalledtheStreisandeffect.TheproblemforanyonetryingtosuppressinformationisthattheInternetistheworld'sbiggestandmostefficientcopyingmachine.Putadocumentontoaconnectedmachineanditwillspread.Sowhenyouwanttobefamousyoucan'tbutifyoufindyourselfinthespotlightandwanttoeraseyourselfyoucannot. ThereisnoshortageofexamplesoftheStreisandeffect.Nine﹣year﹣oldMarthaPaynecreatedasimpleblogpostingthemealsherschoolserved.Shetookaphotoofwhatwasbarelyafillingmealbyanyone'sstandards.WiththephotoshefilledacommentNowDadunderstandswhyIamhungrywhenIgethome.ThethingdidnotgotoofaruntilthelocalauthoritybannedlittleMarthafromdoingthatagain.MarthapostedasupposedlyfinalpostcalledGoodbyeexplainingeverything.Oncethemediafoundthisoutthingswentfrombadtoworsefortheauthority.Nowthebloghasmorethan9.5millionpageviews.MarthahasevenexpandedherblogbyincludingpicturesofschoolmealstakenbyotherkidsfromallovertheworldlikeGermanyandJapan. Wecanfindsimilarexamplesthroughouthistorytobefrank.ManhasexperiencedtheStreisandeffecteversincethebirthofmasscommunication.Whydoesitexist?Everytimeyouaretoldnottoseewhat'sinthesecretshinyboxwrappedingiftpaperyou'regoingtodoeverythinginyourpowertodoexactlythat!Justrealizingthatknowingsomethingaboutsomeoneisharmfultotheirstatuswewillwanttoknowthatpieceofinformation.Thisisexactlythehumannature.Thisiswhatlawyersandauthoritiesshouldbefamiliarwith.Unfortunatelyafewofthemfailtograspit. 1.TheunderlinedwordsuppressinParagraph2probablymeans. A.giveaway B.lookinto C.coverup D.searchfor 2.WhatspeededupthespreadofMartha'sstory? A.Parents'complaints. B.Theauthority'sorder. C.Thephotosofotherkids. D.Supportingfromtheschool. 3.Whatisthelastparagraphmainlyabout? A.TherootofStreisandeffect. B.TheinfluenceofStreisandeffect. C.People'sreactiontoStreisandeffect. D.HistoricalexamplesofStreisandeffect.
Morestudentsthaneverbeforearetakingagap﹣year间隔年beforegoingtouniversity.Itusedtobecalledtheyearoffbetweenschoolanduniversity.Thegap﹣yearphenomenonoriginated起源withthemonthsleftovertoOxbridgeapplicantsbetweenentranceexamsinNovemberandthestartofthenextacademicyear. Thisyear25310studentswhohaveacceptedplacesinhighereducationinstitutionshaveputofftheirentryuntilnextyearaccordingtostatisticsonuniversityentranceprovidedbyUniversityandCollegeAdmissionsSerbiceUCAS. Thatisarecord14.7%increaseinthenumberofstudentstakingagapyear.TonyHigginsfromUCASsaidthatthestatisticsaregoodnewsforeveryoneinhighereducation.Studentswhotakeawell﹣plannedyearoutaremorelikelytobesatisfiedwithandcompletetheirchosencourse.Studentswhotakeagapyearareoftenmorematureandresponsiblehesaid. Butnoteveryoneishappy.OwainJamesthepresidentoftheNationalUnionofStudentsNUSarguedthattheincreaseisevidenceofstudenthadship﹣youngpeoplearebeingforcedintoearningmoneybeforefinishingtheireducation.Newstudentsarenowawarethattheyarelikelytoleaveuniversityupto￡15000indebt.Itisnotsurprisingthatmoreandmorestudentsaretakingagapyeartoearnmoneytosupporttheirstudyforthedegree.NUSstatisticsshowthatover40%ofstudentsareforcedtoworkduringtermtimeandthefigureincreasesto90%duringvacationperiodshesaid. 29.Whatdowelearnaboutthegapyearfromthetext? A.Itisflexibleinlength. B.Itisatimeforrelaxation. C.Itisincreasinglypopular. D.Itisrequiredbyuniversities. 30.AccordingtoTonyHigginsstudentstakingagapyear. A.arcbetterpreparedforcollegestudies B.knowalotmoreabouttheirfuturejobs C.aremorelikelytoleaveuniversityindebt D.haveabetterchancetoentertopuniversities 31.HowdoesOwainJamesfeelaboutthegap﹣yearphenomenon? A.He'spuzzled. B.He'sworried. C.He'ssurprised. D.He'sannoyed. 32.WhatwouldmoststudentsdoontheirvacationaccordingtoNUSstatistics? A.Attendadditionalcourses. B.Makeplansforthenewterm. C.Earnmoneyfortheireducation. D.Preparefortheirgraduatestudies.
组成种群的个体在生活空间中的位置状态主要有三种均匀分布随机分布和集群分布．以下说法错误的是
一定温度压强下在容积可变的密闭容器中发生反应COg+H2Og⇌CO2g+H2g△H＜0则下列说法不正确的是
光补偿点a是光合作用速率等于呼吸作用速率时的光照强度光饱和点b是光合作用速率最大时的最小光照强度．在一定范围内当光强在a点以上继续增加时光合作用速率呈比例地增加光合作用速率和光照强度呈直线关系．请回答相关问题． 1假如光照12h__12h要保证作物正常生长平均光照强度至少应控制在以上． 2种植过密的作物群体中底层叶片所受的光照往往在a点以下．这些叶片由于进而造成作物减产． 3从结构上看阴生植物用于运输水分和有机物的输导组织欠发达据此解释为什么阴生植物的光饱和点一般较低．
6分 DT WhenBarbraStreisanddiscoveredin2003thataphotographofherCaliforniabeachhousewasamong12000photosontheInternetaspartofacollectionbyphotographerKennethAdelmanshedidwhatanyfamouspersonwoulddohithimwitha﹩50millionlawsuit.Butintryingtoholdbacktheimagesshecausedadifferentoutcome.Herlegalactionsledtoalmosthalfamillionpeoplevisitingthewebsiteviewingandcopyingthephotoswithinamonth. EversincethentheeffectoflettingpublicknowsomethingyouaretryingtokeepsecrethasbeencalledtheStreisandeffect.TheproblemforanyonetryingtosuppressinformationisthattheInternetistheworld'sbiggestandmostefficientcopyingmachine.Putadocumentontoaconnectedmachineanditwillspread.Sowhenyouwanttobefamousyoucan'tbutifyoufindyourselfinthespotlightandwanttoeraseyourselfyoucannot. ThereisnoshortageofexamplesoftheStreisandeffect.Nine﹣year﹣oldMarthaPaynecreatedasimpleblogpostingthemealsherschoolserved.Shetookaphotoofwhatwasbarelyafillingmealbyanyone'sstandards.WiththephotoshefilledacommentNowDadunderstandswhyIamhungrywhenIgethome.ThethingdidnotgotoofaruntilthelocalauthoritybannedlittleMarthafromdoingthatagain.MarthapostedasupposedlyfinalpostcalledGoodbyeexplainingeverything.Oncethemediafoundthisoutthingswentfrombadtoworsefortheauthority.Nowthebloghasmorethan9.5millionpageviews.MarthahasevenexpandedherblogbyincludingpicturesofschoolmealstakenbyotherkidsfromallovertheworldlikeGermanyandJapan. Wecanfindsimilarexamplesthroughouthistorytobefrank.ManhasexperiencedtheStreisandeffecteversincethebirthofmasscommunication.Whydoesitexist?Everytimeyouaretoldnottoseewhat'sinthesecretshinyboxwrappedingiftpaperyou'regoingtodoeverythinginyourpowertodoexactlythat!Justrealizingthatknowingsomethingaboutsomeoneisharmfultotheirstatuswewillwanttoknowthatpieceofinformation.Thisisexactlythehumannature.Thisiswhatlawyersandauthoritiesshouldbefamiliarwith.Unfortunatelyafewofthemfailtograspit. 1.TheunderlinedwordsuppressinParagraph2probablymeans. A.giveaway B.lookinto C.coverup D.searchfor 2.WhatspeededupthespreadofMartha'sstory? A.Parents'complaints. B.Theauthority'sorder. C.Thephotosofotherkids. D.Supportingfromtheschool. 3.Whatisthelastparagraphmainlyabout? A.TherootofStreisandeffect. B.TheinfluenceofStreisandeffect. C.People'sreactiontoStreisandeffect. D.HistoricalexamplesofStreisandeffect.
Vacationisatimeforrefreshment.Inworkweareoftencalledtothink.Sometimesit'sgoodtogiveourbrainsarest.Withoutabreakwemaynotbeabletoperformuptoourpotential.Thiscanbeaproblemnotonlyfortheemployeebutfortheemployeraswell. ThemainbenefitofvacationisfortheworkertocomebackenergizedsaysWeaver.Iftheyhaven'thadabreakthenthey'renotcomingbackwithnewenergy.Theyhaven'thadachancetostepbackandgetperspective远景andcomebackwithrenewedenthusiasm. Longworkinghourswithoutabreakinsecurity不安aboutone'sjobandotherwork﹣relatedworriescanleadtoburnoutandstress.Humanscanusuallyadapttopressurebutnotforalimitlessamountoftime. Itisaproblemofrelatinggoodworkersandhavingthemloyaltothefirmwhilethey'retheresaysDavidMaumePhDprofessorofsociologyattheUniversityofCincinnati.Hesaysburnoutcanalsoaffectemployees'productivitycreativityandeffectiveness. Inadditionhighlevelsofstressarelikelytobeprecursors前兆todepressionwhichcanhitboththeemployerandemployee'spocketbook.Evenpeoplewhomanagetoremainproductiveatworkcanhaveproblems.Ifthey'realwaysatworkthenthey'renotwiththeirfamilyandfriends.Ifthey'reworkingwhileonvacationforthetimethatthey'reonthejobthey'renotreallypresent. Anunbalancedemphasisonworkcanstrainfamilyandsociallife.Whenyoucomeupforairyoumayseethatyou'realoneorthatyourrelationshipshavegoneonwithoutyou. 1.What'sthemainbenefitofavacation? A.Themanagercanbemorecreative. B.Theworkercanstepbackandgetmoreexcited C.Theworkercancomebackwithnewenergy. D.Theworkercanadapttopressuremuchbetter. 2.Theunderlinedwordthereinthefourthparagraphprobablyrefersto. A.thevacation B.thehome C.theuniversity D.thecompany 3.Whenaworkerisalwaysatworkheislikelytogetmoreandmore. A.absent﹣minded B.energetic C.skillful D.active 4.Whichofthefollowingisthebesttitleofthetext? A.Howtospendthevacationeffectively. B.Whytheworkersneedavacation. C.Howtodealwiththedailypressure. D.Whytheworkersneednewenergy.
一个铀核U发生裂变核反应方程是U+n→Ba+K+3X并出现质量亏损．则
某种H+﹣ATPase是一种位于膜上的载体蛋白具有ATP水解酶活性能够利用水解ATP释放的能量逆浓度梯度跨膜转运H+．①将某植物气孔的保卫细胞悬浮在一定pH的溶液中假设细胞内的pH高于细胞外置于暗中一段时间后溶液的pH不变．②再将含有保卫细胞的该溶液分成两组一组照射蓝光后溶液的pH明显降低另一组先在溶液中加入H+﹣ATPase的抑制剂抑制ATP水解再用蓝光照射溶液的pH不变．根据上述实验结果下列推测不合理的是
Theadobedwellings土坯房61buildbythePuebloIndiansoftheAmericanSouthwestareadmiredbyeven62mostmodernofarchitectsandengineers.Inadditiontotheirsimplebeautywhatmakestheadobedwellingsadmirableistheir63abletoairconditionahousewithout64useelectricequipment.Wallsmadeofadobetakeintheheatfromthesunonhotdaysandgiveoutthatheat65slowduringcoolnightsthuswarningthehouse.Whenanewdaybreaksthewallshavegivenuptheirheatandarenowcoldenough66coolthehouseduringthehotday67thesametimetheywarmupagainforthenightThiscycle68godayafterdayThewallswarmupduringthedayandcooloffduringthenightandthusalwaysatimelyoffset抵消fortheoutsidetemperatures.As69naturearchitectsthePuebloIndiansfiguredoutexactly70thicktheadobewallsneededtobetomakethecycleworkonmostdays. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70.
Yourhousemayhaveaneffectonyourfigure.Expertssaythewayyoudesignyourhomecouldplayaroleinwhetheryoupackonthepoundsorkeepthemoff.Youcanmakeyourenvironmentworkforyouinsteadofagainstyou.Herearesomewaystoturnyourhomeintopartofdietplan. Openthecurtainsandturnupthelights.Darkenvironmentsaremorelikelytoencourageovereatingforpeopleareoftenlessself﹣consciouswhenthey'reinpoorlylitplaces﹣andsomorelikelytoeatlotsoffood.Ifyourhomedoesn'thaveenoughwindowlightgetmorelampsandfloodtheplacewithbrightness. Mindthecolors.Researchsuggestswarmcolorsfuelourappetites胃口.Inonestudypeoplewhoatemealsinablueroomconsumed消耗33percentlessthanthoseinayelloworredroom.Warmcolorslikeyellowmakefoodappearmoreappetizingwhilecoldcolorsmakeusfeellesshungry.Sowhenit'stimetorepaintgoblue. Don'tforgettheclock﹣﹣﹣ortheradio.Peoplewhoeatslowlytendtoconsumeabout70fewercalories卡路里permealthanthosewhorushthroughtheirmeals.Beginkeepingtrackofthetimeandtrytomakedinnerlastatleast30minutes.Andwhileyou'reatitactuallysitdowntoeat.Ifyouneedsomehelpslowingdownturnonrelaxingmusic.Itmakesyoulesslikelytorushthroughameal. Downsizethedishes.Bigservingbowlsandplatescaneasilymakeusfat.Weeatabout22percentmorewhenusinga12﹣inchplateinsteadofa10﹣inchplate.Whenwechoosealargespoonoverasmalleronetotalintake摄入jumpsby14percent.Andwe'llpourabout30percentmoreliquidintoashortwideglassthanatallskinnyglass. 1.Thetextisespeciallyhelpfulforthosewhocareabout. A.theirhomecomforts B.theirbodyshape C.housebuying D.healthydiets 2.Ahomeenvironmentinbluecanhelppeople. A.digestfoodbetter B.regaintheirappetites C.burnmorecalories D.reducefoodintake 3.Whatarepeopleadvisedtodoatmealtimes? A.Fatquickly. B.Playfastmusic. C.Usesmallerspoons. D.Turndownthelights. 4.Whatcanbeasuitabletitleforthetest? A.IsYourHouseMakingYouFat? B.WaysofServingDinner C.EffectsofSelf﹣Consciousness D.IsYourHomeEnvironmentRelaxing?
某种植物的羽裂叶和全缘叶是一对相对性状．某同学用全缘叶植株植株甲进行了下列四个实验． ①让植株甲进行自花传粉子代出现性状分离 ②用植株甲给另一全缘叶植株授粉子代均为全缘叶 ③用植株甲给羽裂叶植株授粉子代中全缘叶与羽裂叶的比例为11 ④用植株甲给另一全缘叶植株授粉子代中全缘叶与羽裂叶的比例为31 其中能够判定植株甲为杂合子的实验是
回答下列与生态系统相关的问题． 1在森林生态系统中生产者的能量来自于生产者的能量可以直接流向答出2点即可． 2通常对于一个水生生态系统来说可根据水体中含氧量的变化计算出生态系统中浮游植物的总初级生产量生产者所制造的有机物总量．若要测定某一水生生态系统中浮游植物的总初级生产量可在该水生生态系统中的某一水深处取水样将水样分成三等份一份直接测定O2含量A另两份分别装入不透光甲和透光乙的两个玻璃瓶中密闭后放回取样处若干小时后测定甲瓶中的O2含量B和乙瓶中的O2含量C．据此回答下列问题． 在甲乙瓶中生产者呼吸作用相同且瓶中只有生产者的条件下本实验中C与A的差值表示这段时间内C与B的差值表示这段时间内A与B的差值表示这段时间内．
下列根据实验操作和现象所得出的结论正确的是
某研究小组切取某种植物胚芽鞘的顶端分成甲乙两组按如图所示的方法用琼脂块收集生长素再将含有生长素的琼脂块置于去顶胚芽鞘切段的一侧一段时间后测量胚芽鞘切段的弯曲程度α角测得数据如下表据此回答问题． 1生长素在胚芽鞘中的运输属于极性运输这种运输的方向是． 2如图中α角形成的原因是． 3据表可知乙组中左右两侧的琼脂块所引起的α角基本相同但小于甲琼脂块所引起的α角原因是．
在真核细胞的内质网和细胞核中能够合成的物质分别是
传统果园常进行单一化种植经常爆发病虫害．某生态果园采用“果一草一禽牧”立体种养模式如图．请回答相关问题． 1传统果园容易爆发病虫害的原因是． 2图中果树饲草可以为鸡鹅兔等动物提供． 3与传统果园相比该生态果园具有哪三个方面的优势
如图所示用半径相同的AB两球的碰撞可以验证“动量守恒定律”．实验时先让质量为m1的A球从斜槽轨道上某一固定位置S由静止开始滚下从轨道末端抛出落到位于水平地面的复写纸上在下面的白纸上留下痕迹．重复上述操作10次得到10个落点痕迹．再把质量为m2的B球放在斜槽轨道末端让A球仍从位置S由静止滚下与B球碰撞后分别在白纸上留下各自的落点痕迹重复操作10次．MPN为三个落点的平均位置． ①实验中直接测定小球碰撞前后的速度是不容易的．但是可以通过测量间接地解决这个问题． A．小球开始释放高度hB．小球抛出点距地面的高度HC．小球做平抛运动的射程 ②以下提供的测量工具中本实验必须使用的是多选． A．刻度尺B．天平C．游标卡尺D．秒表 ③关于本实验下列说法正确的是． A．斜槽轨道必须光滑B．斜槽轨道末端必须水平C．实验过程中复写纸和白纸都可以移动 ④在实验误差允许范围内若满足关系式则可以认为两球碰撞前后总动量守恒． A．m1．OP＝m1．OM+m2•ONB．mc．OP＝m1．ON+m2．OM C．m1．OM＝m1．OP+m2．OND．m1．ON＝ml．OP+m2．OM ⑤在实验中为了让A球碰后沿原方向运动应满足A球的质量m1大于B球的质量m2请推理说明．
如图所示一理想变压器的原线圈接正弦交流电源副线圈接有电阻R和小灯泡．电流表和电压表均可视为理想电表．闭合开关S下列说法正确的是
光子除了有能量还有动量．若光子能量为E动量为J则光子动量p＝式中c为真空中的光速．当光照射到物体表面上时不论光被物体吸收还是被物体表面反射光子的动量都会发生改变因而对物体表面产生一种压力． 如图是1901年俄同物理学家列别捷夫测量光压的实验装置．T型架通过悬丝竖直悬挂横臂水平悬丝一端同定在横臂中点．在横臂的两侧有圆片P和Q两圆片与T型架在同一竖直平面内．圆片P是涂黑的当光线照射到P上时可以认为光子全部被吸收圆片Q是光亮的当光线照射到Q上时可以认为光子全部被反射．分别将光线照射在P或Q上都可以引起悬丝的旋转．在悬丝上固定一__面M用一细光束照射时就可以获知悬丝扭转的角度．已知光速为c两个圆片PQ的半径都为r．悬丝转过的角度与光对网片的压力成正比． a．用光强单位时间内通过与传播方向垂直的单位面积的光能为I0的激光束垂直照射整个圆片P求激光束对圆片P的压力F2的大小 b．实验中第一次用光强厶为的激光束单独照射整个圆片P平衡时光束与圆片垂直且悬丝有一扭转角第二次仍用该光束单独照射整个圆片Q平衡时光束与圆片不垂直悬丝的扭转角与第一次相同．求激光束与圆片Q所在平面的夹角φ．
Mycolortelevisionhasgivenmenothingbutaheadache.IwasabletobuyitalittleoverayearagobecauseIhadmyrelativesgivememoneyformybirthdayinsteadofalotofclothesthatwouldn'tfit.IletasalesclerkfoolmeintobuyingadiscontinuedmodelIrealizedthisadaylatewhenIsawnewspaperadvertisementsforthesetatseventy﹣fivedollarslessthanIhadpaidThesetworkedsobeautifullywhenIfirstgotithomethatIwouldkeepitonuntilstationssignedoffforthenightFortunatelyIdidn'tgotanychannelsshowingall﹣nightmoviesorIwouldneverhavegottentobed. ThenIstarteddevelopingaproblemwiththesetthatinvolvedstatic静电noise.Forsomereasonwhencertainshowsswitchedintoacommercialaloudnoisewouldsoundforafewseconds.GraduallythisnoisebegantoappearduringashowandtogetridofitIhadtochangetoanotherchannelandthenchangeitback.SometimesthistechniquewouldnotworkandIhadtopickupthesetandshakeittoremovethesound.Iactuallybegantobuildupmyarmmuscles肌肉shakingmyset. WhenneitherofthesemethodsremovedthestaticnoiseIwouldsithelplesslyandwaitforthenoisetogoaway.AtlastIendeduphittingthesetwithmyfistanditstoppedworkingaltogether.Mytriptotherepairshopcostme$62andthesetisworkingwellnowbutIkeepexpectingmoretrouble. 21.WhydidtheauthorsayhewasfooledintobuyingtheTVset? A.Hegotanoldermodelthanhehadexpected. B.Hecouldn'treturnitwhenitwasbroken. C.Hecouldhaveboughtitatalowerprice. D.Hefailedtofindanymovieshowsonit. 22.WhichofthefollowingcanbestreplacethephrasesignedoffinParagraph1? A.endedalltheirprograms B.providedfewerchannels C.changedtocommercials D.showedall﹣nightmovies 23.HowdidtheauthorfinallygethisTVsetworkingagain? A.Byshakingandhittingit. B.Byturningitonandoff. C.Byswitchingchannels. D.Byhavingitrepaired. 24.Howdoestheauthorsoundwhentellingthestory? A.Curious B.Anxious C.Cautious D.Humorous.
如图为香芹酮分子的结构下列有关叙述正确的是
直流电动机的基本结构由永磁铁和矩形线圈构成如图1所示．现将标有“3V3W”的直流电动机串联一个滑动变阻器接在电动势为E＝4.0V内阻为r＝0.40Ω的电源的两端如图2所示．已知电动机线圈的电阻R0＝0.10Ω不计其它电阻． 1若滑动变阻器接入电路的阻值R1＝3.5Ω且电动机卡住不转求此时电路中的电流I1． 2调节滑动变阻器接入电路的阻值或电动机工作时的负载发生变化回路中的电流I及电源的输出功率P随之改变． a．请从理论上推导P与I的关系式并在图3中定性画出P﹣I图象 b．求该电源对外电路能够输出的最大功率Pm． 3调节滑动变阻器接入电路的阻值使电动机正常工作．现保持滑动变阻器接入电路的阻值不变增加电动机的负载电动机将通过转速调节达到新的稳定状态．请分析说明在这个过程中电路中的电流如何变化．
物质W是一种含氮有机物会污染土壤．W在培养基中达到一定量时培养基表现为不透明．某研究小组欲从土壤中筛选出能降解W的细菌目标菌．回答下列问题． 1要从土壤中分离目标菌所用选择培养基中的氮源应该是． 2在从土壤中分离目标菌的过程中发现培养基上甲乙两种细菌都能生长并形成菌落如图所示．如果要得到目标菌应该选择菌落进一步纯化．选择的依据是． 3土壤中的某些微生物可以利用空气中的氮气作为氮源若要设计实验进一步确定甲乙菌能否利用空气中的氮气作为氮源请简要写出实验思路预期结果和结论即． 4该小组将人工合成的一段DNA转入大肠杆菌使大肠杆菌产生能降解W的酶酶E．为了比较酶E与天然酶降解W能力的差异该小组拟进行如下实验请完善相关内容． ①在含有一定浓度W的固体培养基上A处滴加含有酶E的缓冲液B处滴加含有相同浓度天然酶的缓冲液C处滴加三处滴加量相同． ②一段时间后测量透明圈的直径．若C处没有出现透明圈说明若AB处形成的透明圈直径大小相近说明．
Theadobedwellings土坯房61buildbythePuebloIndiansoftheAmericanSouthwestareadmiredbyeven62mostmodernofarchitectsandengineers.Inadditiontotheirsimplebeautywhatmakestheadobedwellingsadmirableistheir63abletoairconditionahousewithout64useelectricequipment.Wallsmadeofadobetakeintheheatfromthesunonhotdaysandgiveoutthatheat65slowduringcoolnightsthuswarningthehouse.Whenanewdaybreaksthewallshavegivenuptheirheatandarenowcoldenough66coolthehouseduringthehotday67thesametimetheywarmupagainforthenightThiscycle68godayafterdayThewallswarmupduringthedayandcooloffduringthenightandthusalwaysatimelyoffset抵消fortheoutsidetemperatures.As69naturearchitectsthePuebloIndiansfiguredoutexactly70thicktheadobewallsneededtobetomakethecycleworkonmostdays. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70.
AsakidIlovedeverythingaboutschool.Ilovedbooks1testsandhomework.MostofallIlongedtosomedaymarchdowntheaisle通道toreceivemy2.Thatseemedmoreappealingeventhangettingmarried.Butat15Ihadto3becausemyparents4affordtuition学费.Myhopeofgettingadiplomawasdead. PrettysoonImarried.IhadthreeChildrenandIthoughtThere5mydiploma.EvensoIwantedmychildrentobeeducated.ButLindaouryoungestchildhadjuvenilearthritis幼年型关节炎inher6andkneeswhichmadeit7forhertofunctioninanormalclassroom. OnedayIsawanadinthenewspaperforeveningcourses. That'stheanswerIsaidtomyself.Lindaalwaysfeels8intheeveningsoI'lljustsignherupfornightschool. Lindawasbusy9outenrollment入学formswhenthesecretarysaidMrsSchantzwhydon'tyoucomebackto10? I11There'snoway!I'm! 12heinsistedandbeforeIknewwhatIhaddoneIwasenrolledforclassesinEnglishandcrafts.ThisisonlyanexperimentI13himbuthejustsmiled.TomysurprisebothLindaandIthrived茁壮成长ineveningschool.Iwentbackagainthenextsemesterandmygrades14improved. Itwas15togotoschoolagainbutitwasnogame.Sittinginaclassfullofkidswasawkward16mostofthemwererespectfulandencouraging.DuringthedayIstillhadloadsofhouseworktodo.ButwhenIwasdownLindaencouragedme.Mumyoucan't17now!AndwhenshewasdownI18her.Togetherwesawitthrough.AtlastIgotmydiploma.19myclassmatesvotedunanimously一致地formetobeclassspeakerandIgota$3000collegescholarship. YesMumIwaslateforschoolbutIgotthere20. 1.A.parents B.teachers C.trees D.flowers 2.A.job B.present C.certification D.diploma 3.A.dropout B.watchout C.keepout D.findout 4.A.wouldn't B.couldn't C.shouldn't D.needn't 5.A.goes B.comes C.exists D.breaks 6.A.hands B.head C.eyes D.stomach 7.A.1ikely B.frequent C.easy D.impossible 8.A.Worse B.excited C.better D.annoyed 9.A.giving B.taking C.filling D.sending 10.A.work B.school C.home D.office 11.A.laughed B.told C.argued D.shouted 12.A.And B.But C.Although D.So 13.A.informed B.asked C.warned D.convinced 14.A.regularly B.happily C.steadily D.naturally 【考点】记叙文人生感悟类阅读 【分析】文章讲述了作者小时候很喜欢上学因为父母负担不起学费而辍学.她55岁时和女儿一起上夜校并获得了大学奖学金最终实现了自己小时候的梦想. 【解答】C副词辨析.regularly有规律地happily开心地steadily稳定地natumlly自然地.我的成绩稳步提高.故选C. 【点评】完型填空题的命题趋势 【备注】1#1#1#C ~15.A.interesting B.disappointing C.concerned D.exciting 16.A.asif B.evenif C.incase D.ifonly 17.A.continue B.rest C.quit D.hesitate 18.A.raised B.discouraged C.cheered D.defeated 19.A.Tomysurprise B.Tomysatisfaction C.Tomyrelief D.Tomycredit 20.A.naturally B.frequently C.constantly D.eventually
某课题组就固氮菌和纤维素分解菌混合培养对纤维素降解的效果进行研究实验步骤大致如下取250mL三角瓶装入50mL基础培养基接种不同比例的混合菌种放入滤纸条150r/min摇床振荡培养．根据滤纸条的分解情况测定纤维素酶的活性实验结果如表． 1上述实验中培养基中填需要”或“不需要”加入琼脂滤纸条的作用是． 2完成上述实验时还必须进行． 3由上表可得出如下实验结论． 4有同学推测混合培养也能促进固氮菌的生长理由是．若想比较IIIIIIV组的固氮菌数目实验思路如下最后统计各组固氮菌的菌落数．
Trainingforamarathonrequirescarefulpreparationandsteadygradualincreasesinthelengthoftheruns.36buythebest﹣fittingbest﹣builtrunningshoesyoucanfind.Noonecansaywhichbrandwillworkbestforyouorfeelbestonyourfeetsoyouhavetorelyonyourexperienceandonthefeelofeachpairasyoushop.Whenyouhavefoundshoesthatseemrightwalkinthemforafewdaystodouble﹣checkthefit.37.Asalwaysyoushouldstretch伸展atleasttenminutesbeforeeachruntopreventinjuries. Duringthefirstweekdonotthinkaboutdistancebutrunfiveminuteslongereachday.38itiswisetotakeadayofftorest.Butduringthenextweeksetagoalofatleastamileandahalfperrun.39.Aftertwoweeksstarttimingyourself.40.Dependingonthekindofraceyouplantoenteryoucansetupatimetablefortheremainingweeksbeforetherace. A.Aftersixdays B.Foragoodmarathonrunner C.Beforeyoubeginyourtraining D.Witheachdayincreasethedistancebyahalfmile E.Iftheystillfeelgoodyoucanbeginrunninginthem F.Timespentforpreparationraisesthequalityoftraining G.Nowyouarereadytofigureoutagoalofimprovingdistanceandtime. 36. 37. 38. 39. 40.
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