小明在一个半圆形的花园的周边散步，如图1，小明从圆心O出发，按图中箭头所示的方向，依次匀速走完下列三条线路：（1）线段OA；（2）半圆弧AB；（3）线段BO后，回到出发点．小明离出发点的距离S（小明所在位置与O点之间线段的长度）与时间t之间的图象如图2所示，请据图回答下列问题（圆周率π的值取3）：（1）请直接写出：花园的半径是　 　米，小明的速度是　 　米/分，a=　 　；（2）若沿途只有一处小明遇到了一位同学停下来交谈了2分钟，并且小明在遇到同学的前后，始终保持速度不变，请求出：①小明遇到同学的地方离出发点的距离；②小明返回起点O的时间．

Brookewantedadollhouseandsomesugarcookies.Sothe6﹣year﹣oldaskedAlexatogetthem.Alexawasn'thermomorbabysitter.It wasavoice﹣activatedhomeassistantpoweredbyAI人工智能.AnditmadeBrooke'swishescometrue.Afewdayslatermuchtoherparents'surprisea﹩170dollhouseandfourpoundsofcookiesshowedup.Theyatethecookiesandgaveawaythedollhousetoalocalhospital.Andthat'snottheendofthestory.WhenanewsreportertoldthestoryofwhathappenedonTVAlexadevices设备inmanylisteners'homeswokeupandtriedtoorderdollhouses! Alexaisn'ttheonlyAIwillingtoserveyou.AppleHomePodhasSiriGoogleHomehasitsAssistantandtheupcomingGalaxyHomedevicewillhaveBixby.Peoplewho havethesedevicesusethemmainlyforlisteningtomusiccheckingtheweatherandsettingtimers.AccordingtoareportfromTheInformationnowadaysvoiceshoppingisrare.Butmanyscientistspredict aboom增长invoiceshoppinginthenearfuture.Isthatagoodthing? ▲.Youcanshoutoutanorderassoonasyouthinkofitevenifyouarecookingcleaningordriving.Inadditionpeoplewithdisabilitieswhoareunabletouseakeyboardormousecanshopwithoutanyhelp. Butvoiceshoppinghasitsdisadvantages.Unwanteddollhousesaren'tthebiggestproblem.It'susuallyveryeasytocancelanorderorreturnproducts.Thethingthatworriessomepeopleisthattheseassistantsarealwayslistening.Theyhavetobeabletorespondwhenyouwantthem.SotheylistenforAlexaorOKGoogleoranotherorder.Whentheyhearittheystartrecordingtheconversation.Somehaveworriedaboutwhathappensshoppinghabits?Andwhatifsomeonehacks入侵thedevice?TheCIAfoundawaytohacksmartTVstoturnthemintospiesthatlistenallthetime.Otherscoulddothesamewithanysmartdevice. Whatdoyouthink?Areyoureadytostartvoiceshopping? 1FromthepassageweknowthatAlexa. A.canlookafterthebaby B.cancookdeliciousfood C.isatoydollsoldonline D.isonekindofAIdevice 2TheunderlinedwordrareinParagraph2probablymeans. A.unusual B.expensive C.harmful D.impossible 3Whichofthefollowingisthebesttofillinthe▲inParagraph3? A.Convenienceisthemainadvantageofvoiceshopping B.Thecostofvoiceshoppingislowerthanotherways C.Thepopularityofvoiceshoppingisincreasing D.Thetechnologyofvoiceshoppingneedsimproving 4Paragraph4mainlytellsusthatwhenpeopletryvoiceshopping. A.AIsometimesforgetspeople'sorders B.personalinformationmightbehacked C.It'sdifficulttocancelorreturnproducts D.theneedsforproductscan'tbesatisfied

某公园要建造一个圆形喷水池在水池中央垂直于水面竖一根柱子上面的A处安装一个喷头向外喷水水流在各个方向上沿形状相同的抛物线路径落下如图1所示.根据设计图纸已知在图2中所示直角坐标系中水流喷出的高度ym与水平距离xm之间的函数关系式是y=-x²+2x+．1柱子OA的高度是多少米2喷出的水流距水平面的最大高度是多少3如果不计其他因素那么水池的半径至少为多少时才能使喷出的水流都落在水池内

已知三角形ABC的面积是c＝1a＝则b等于

Samfindssweepingrobotsusefulandheplanstobuy_forhisgrandma. A.it B.one C.this D.that

在各项均为正数的等比数列{an}中若log2a2+log2a8＝1则a3•a7＝．

计算1-++×-12运用哪种运算律可以避免通分

如图所示AB为两个质量相等的小球由细线相连再用轻质弹簧悬挂起来在AB间细线烧断后的瞬间AB的加速度分别是

求证矩形的四个顶点在以对角线的交点为圆心的同一个圆上．

1若2kx＜x2+4对于一切的x∈R恒成立求k的取值范围 2若关于x的不等式2x＞mx2+6的解集为{x|x＜﹣3或x＞﹣2}求不等式5mx2+x+3＞0的解集

Hereisthepenyoulostthedaybeforeyesterday.

smokeisn'tallowedhere.

已知函数fx＝|x﹣a2|+|x﹣2a+3|gx＝x2+ax+4a∈R． 1当a＝1时解关于x的不等式fx≤4 2若对任意x1∈R都存在x2∈R使得不等式fx1＞gx2成立求实数a的取值范围．

Wedon'tallowtakingmagazinesoutbutyou  copythearticleyouneedonthemachineoverthere.A.can B.must C.should D.would

道路交通安全法第四十七条规定机动车行经人行横道应减速行驶遇行人正在通过人行横道时应停车让行．一辆汽车以36km/h的速度匀速行驶驾驶员发现前方50m处的斑马线上有行人驾驶员立即刹车使车做匀减速直线运动若已知行人还需12s才能通过斑马线则刹车后汽车的加速度大小至少为

ThatisthesupermarketIboughtthispairofsocks. A.where B.that C.who D.which

—Canyoucomeandplayfootballwithme? —.Ihavealotofhomeworktodo. A.I'dliketo B.I'mafraidso C.It'sapleasure D.I'mafraidnot

已知数列{an}的通项公式为an＝n+则a2＞a1是数列{an}单调递增的

某服装店为庆祝开业三周年举行为期六天的促销活动规定消费达到一定标准的顾客可进行一次抽奖活动随若抽奖活动的有效开展第五天该服装店经理对前五天中参加抽奖活动的人数进行统计y表示第x天参加抽奖活动的人数得到统计表格如下 1若y与x具有线性相关关系请根据上表提供的数据用最小二乘法求出y关于x的线性回归方程． 2预测第六天的参加抽奖活动的人数按四舍五入取到整数． 参考公式与参考数据．

我国魏晋时期的数学家刘徽创立了用圆内接正多边形面积无限逼近圆面积的方法称为割圆术为圆周率的研究提供了科学的方法．在半径为1的圆内任取一点则该点取自圆内接正十二边形外的概率为

已知a＝log30.3b＝30.3c＝0.33则

如图所示斜面倾角为θ位于斜面底端A正上方的小球以不同的初速度v0正对斜面顶点B水平抛出小球到达斜面经历的时间为t重力加速度为g则下列说法正确的是

计算×-1.2×-

用金属丝制成一个U型架一段细长棉线两端紧扣在U型架两臂上AB两点细线中点O处有一扣．将U型架浸入肥皂液中再取出U型架上形成的肥皂液膜如图所示细线被绷紧是因为液体表面层存在表面张力表面张力的作用是使得液面有的趋势用力拉动细线中点的扣至图中虚线位置肥皂液膜未发生破损肥皂液膜的内能将忽略肥皂液膜的蒸发影响

Therearesomevolunteersinthepark. A.表语 B.宾语 C.主语 D.定语

Awoman'sageisa subjectinEngland.

如图所示在水平圆盘上沿半径方向放置物体A和BmA＝4kgmB＝1kg它们分居在圆心两侧与圆心距离为rA＝0.1mrB＝0.2m中间用细线相连AB与盘间的动摩擦因数均为μ＝0.2设最大静摩擦力等于滑动摩擦力若圆盘从静止开始绕中心转轴非常缓慢地加速转动用ω表示圆盘转动的角速度fA表示物体A与圆盘之间的摩擦力取g＝10m/s2． 1细线中出现张力时圆盘转动的角速度ω1 2AB两物体相对圆盘将要滑动时圆盘转动的角速度ω3 3在下列坐标图中分别画出AB两物体滑动前fA随ω2变化的关系图象

如图所示不带电的金属球B接地在B球附近放置一个带正电q的小球AA的重力不计．现由静止开始释放A球在A运动过程中下列说法正确的是

设则下列不等式恒成立的是

一个阻值为8Ω的电阻当其两端的电压从2V增加到2.8V通过该电阻的电流增加了0.1A那么此时该电阻的阻值将不考虑温度对电阻的影响

如图在固定斜面上的一物块受到一外力F的作用F平行于斜面向上．若要物块在斜面上保持静止F的取值应有一定的范围已知其最大值和最小值分别为F1和F2F1和F2的方向均沿斜面向上．由此可求出物块与斜面间的最大静摩擦力为

下列说法正确的有 A．密立根油滴实验精确测定了电子电荷发现了电荷是量子化的  B．氢原子光谱包含红外可见光和紫外光  C．发生光电效应时使光电流为零的遏止电压与入射光的频率成正比  D．原子核核子数越多原子核越不稳定

Asadultyoushouldthinkupyourownideas.A.a B.the C./ D.an

高三学生甲和乙近五次月考数学成绩单位分的茎叶图如图则下列说法错误的是

﹣Shallwegotothesupermarketafterschool?Ineedtobuysomething. ﹣Let'smeetattheschoolgateat500p.m. A.Itdoesn'tmatter B.AreyouOK?  C.Whynot? D.That'sallright

如图所示A是地球的同步卫星B是地球的近地卫星C是地面上的物体ABC质量相等均在赤道平面上绕地心做匀速圆周运动．设ABC做圆周运动的向心加速度为aAaBaC周期分别为TATBTCABC做圆周运动的动能分别为EkAEkBEkC．不计ABC之间的相互作用力下列关系式正确的是 ρ

一个圆柱的轴截面是正方形其侧面积与一个球的表面积相等那么这个圆柱的体积与这个球的体积之比为

这位老人习惯于早上7点起床

1Decemberisthemonthoftheyear. 2Shewantsmetomeetanoldfriendof. 3I'msorrythatthingshadtoendlikethis. 4Hetakesgreatinhischildren'ssuccess. 5Thecompetitionisopentokidssixandtenyearsofage.

PleaseTakemyChildrentoWorkDayPTCWDayfirstbeganasaholidayforhard﹣workingandtiredstay﹣at﹣homemotherstotakeadayoff.Nowthisdayisfitforanyparent.Itwascreatedin2003andiscelebratedeachyearonJune25butitisn'tapublicholiday.Itencouragesfriendsandfamilytotakecareofthechildrensothatthestay﹣at﹣homeparentcanhavesometimetorelax. KamehamehaDayisheldonJune11eachyear.KamehamehatheGreatwasthemonarch君主ofHawaii.Heisfamousandrespectedforestablishing建立theKingdomofHawaiiin1810.KamehamehaDayisapublicholidayinHawaiiandthisisadayoffforpeopleSchoolandmostbusinessesareclosed. D﹣DayiscelebratedintheU.S.tomemorizetheNormandylandingsinFranceonJune61944.OnthedayAmericanarmyandotherAlliedforces盟军foughthardandtheWorldWarⅡWWⅡinEuropewasoversoon.Itisnotapublicholiday.Businesseshavenormalopeninghours. FlagDayiscelebratedonJune14eachyeartohonortheUnitedStatesflag.OnthesamedaytheUnitedStatesArmycelebratesitsbirthday.AlthoughFlagDayisagreatcelebrationacrossthecountryitisnotapublicholiday. 1Ifyouareastay﹣at﹣homeparentwhatcanyoudotorelaxonPTCWDay? A.Takeadayoff. B.Gotoworkearlier. C.Lookafterchildren. D.Dosomehousework. 2Whichisapublicholiday? A.PTCWDay. B.KamehamehaDay. C.D﹣Day. D.FlagDay. 3WhenistheUnitedStatesAmy'sbirthday? A.OnJune6. B.OnJune11. C.OnJune14. D.OnJune25. 4WhatcanweknowaboutD﹣Day? A.ItiscelebratedinFrance. B.TheWWⅡendedbefore1944. C.Businessesareclosedforit. D.TheNormandylandingshappenedin1944.

Ilikethesecondfootballmatchwasheldlastweek. A.which B.who C.that D./

Ireallythewayshebroughtupthosekidsallonherown.

的相反数是绝对值是．

Abirthdayisthedateonewasborn.

在做研究电流与电压电阻间关系的实验时得到如下数据．由表1和表2的数据可以得出的结论是在一定时在一定时

已知fx是奇函数且当x＜0时fx＝﹣eax．若fln2＝8则a＝．

滑雪运动中当滑雪板压在雪地时会把雪内的空气逼出来在滑雪板与雪地间形成一个暂时的气垫从而大大减小雪地对滑雪板的摩擦．然而当滑雪板相对雪地速度较小时与雪地接触时间超过某一值就会陷下去使得它们间的摩擦力增大．假设滑雪者的速度超过4m/s时滑雪板与雪地间的动摩擦因数就会由μ1＝0.25变为μ2＝0.125．一滑雪者从倾角θ＝37°的坡顶A处由静止开始自由下滑滑至坡底BB处为一光滑小圆弧后又滑上一段水平雪地最后停在C处如图所示不计空气阻力坡长L＝26m取g＝10m/s2sin37°＝0.6cos37°＝0.8求 1滑雪者从静止开始到动摩擦因数发生变化所经历的时间 2滑雪者到达B处的速度 3滑雪者在水平雪地上运动的最大距离．

在电阻一定时加在同一段导体两端的电压增大时通过该导体的电流

Youwon'tachieveyourdreamyoureallymakeupyourmindtomakeit A.until B.when C.if D.after

Letmetakeyourtemperaturetoseeifyouhavea.

2019年是中华人民共和国成立70周年某校党支部举办了一场我和我的祖国知识竞赛满分100分回收40份答卷成绩均落在区间[50100]内将成绩绘制成如下的频率分布直方图． 1估计知识竞赛成绩的中位数和平均数． 2从[8090[90100]分数段中按分层抽样随机抽取5份答卷再从对应的党员中选出3位党员参加县级交流会求选出的3位党员中有2位成绩来自于[90100]分数段的概率．

如图平面直角坐标系中有两点A-20B40点P为一次函数y=x+的图象上的动点且△ABP是直角三角形求点P的坐标．

用实验研究电流与电压的关系时是保持来进行的而研究电流与电阻的关系时则是保持来进行．

一般情况下学生的注意力随着老师讲课时间的变化而变化讲课刚开始时学生的注意力逐渐增强中间有一段时间学生的注意力保持较为理想的状态随后学生的注意力开始分散．经过实验分析可知学生的注意力y与时间t关系式为y=1讲课开始后第5min与第25min比较何时学生的注意力更集中2讲课开始后多少分钟学生的注意力最集中能持续多少分钟3有一道数学难题须讲24min要求学生的注意力不低于180那么老师能否在学生注意力达到所需的状态下讲解完这道题

Tinadidn'tfallsleepuntil11o'clock.

Theseedvault种子地窖 Alotofcountriesneeddifferentkindsofseedssothattheycanplantthemagain.ThereisanimportantreasonforthisSometimesplantscan'tgrowinacountrybecauseofbadweatherordiseasesofarmersneednewseeds. Youcankeepseedsinaseedvault.It'saplaceataspecialtemperature.Theseedsdon'tgrowbuttheycanliveforalongtime.Norwayhasthebiggestseedvaultintheworld﹣theSvalbardGlobalSeedVault﹣andithasseedsfromalotofdifferentcountries. ThevaultisontheislandofSpitsbergen.TheislandisaboutonethousandkilometersfromtheNorthPole.It'saverycoldplacesoit'sgoodforseeds.Abovethegroundthedoorwayissmallbutinsidethebuildingishuge.Youwalkdownalongcorridor走廊whichisonehundredandthirtymetersinsideamountain.Attheendofittherearethreelargeareaswithseeds. Thereareabouthalfamillionkindsofseedsinsidethevault.ForexampletherearekindsofseedsforricefromAsiaandAfrica32kindsofseedsforpotatoesfromIrelandandseedsfordifferenttomatoesfromtheUSA. Theseedvaulthasspaceforalotmoreseeds.Youcanputabout2.2billion十亿seedsinside.Theseedscanlivehereforthousandsofyearsbecauseofthecoldtemperatureof﹣18℃.Sointhefuturehumanscangrowanyseedtheywant.Inotherwordstheseedvaultisthedifferencebetweenlifeanddeath. 1Whycan'tplantsgrowinacountry?within6words 2Whereisthebiggestseedvaultintheworld?within2words 3HowfaristheSvalbardGlobalSeedVaultfromtheNorthPole?within4words 4Howmanyseedscanbeputintheseedvault?within3words 5Whatplaceisaseedvault?within12words

已知等差数列{an}的前n项和Sn若S4＝26Sn＝260Sn﹣4＝126n＞4则n＝

跳伞表演是人们普遍喜欢的观赏性体育项目当运动员从直升飞机由静止跳下后在下落过程中不免会受到水平风力的影响下列说法中正确的是

﹣WhendidNeilArmstrongwalkonthemoon? ﹣July20th1969. A.In B.At C.For D.On

计算-1×+1-的结果是

—Isthistheschooltheyusedtostudy?—Noitisn't. A.where B.that C.onwhich D.inwhere

计算-8×69

 Whetherwe'llhaveagoodtimedependsonwhowearegoingwithandwherewearegoing.

如图甲所示一长为l的轻绳一端穿在过O点的水平转轴上另一端固定一质量未知的小球整个装置绕O点在竖直面内转动．小球通过最高点时绳对小球的拉力F与其速度平方v2的关系如图乙所示重力加速度为g下列判断正确的是

他的梦想将会实现.

Cathyisafraidofthedog.Shewillrunaway  sheseesit.A.eversince B.although C.assoonas D.sothat

已知直线1的极坐标方程是ρsinθ+＝2以极点为原点极轴为x轴的非负半轴建立平面直角坐标系两种坐标系中取相同的长度单位曲线C的参数方程为是参数 1求直线1的普通方程与曲线C的直角坐标方程． 2求曲线C上的点到直线1的距离的最小值．

如图一束单色光射入一半径为0.1m玻璃球体入射角为60°已知光线在玻璃球内经一次反射后再次折射回到空气中时与入射光线平行．求 ①此玻璃的折射率 ②光在玻璃球内只有一次反射情况下的传播时间．

meacallbeforeyoucometoChangchun.I'llmeetyouatthestation.A.Give B.Giving C.Togive D.Gave

Theteacheraskedustocirclethe answers.

已知R为实数集集合A＝{x|x2﹣4x﹣5＞0}则∁RA＝

九章算术是我国古代内容极为丰富的数学名著系统地总结了战国秦汉时期的数学成就书中将底面为长方形且有一条侧棱与底面垂直的四棱锥称之为阳马若某阳马的三视图如图所示网格纸上小正方形的边长为1则该阳马外接球表面积为．

Forthousandsofyearshumanshaveexplored探索theEarth.Nowadaysweareexploringspace.Astronomers天文学家arethemodern﹣dayexplorersNowmanyastronomersarelookingfornewplanetsandnewplacesforhumanstoliveinthefuture.Butwheredoastronomersstartlooking? Firstofallastronomerslookforastar.That'sbecauseourownEarthmovesaroundastartheSun.Moreimportantlyitisthecorrectdistance距离fromtheSunforheatandlight.SowhenastronomershavefoundthestartheylookattheplanetsarounditInrecentyearsastronomershavefoundnearly400newplanetswithstars.Howevermanyoftheseplanetsareeithertooneartothestarortoofaraway. Howeveriftheplanetisinagoodpositionastronomerslookforthreekeythingswaterairandrock.Waterisimportantbecausealllifeneedswater.Humanscandrinkitandtheycanalsogrowplantswithwater.Andplantsproduceairforhumanstobreatheandfoodtoeat.Rockonaplanetisalsoimportant.That'sbecausethereisoftenwaterundertherock. Aftermanyyearsofscrutinizing.astronomershavefoundaplanetthatissimilartotheEarth.It'sGliese581gandit'snearastar.Theastronomersthinkithaswaterandrockandtheaverage平均的temperatureisbetween﹣31℃and﹣12℃.That'scoldbutnotcolderthanAntarcticaortheArcticCircleforexample.Gliese581gisbiggerthantheEarth.AyearonGliese581gisonly37Earthdaysinsteadof365.ButastronomersdonotthinkthesearebigdifferencesandsomeofthemthinkGliese581gwillbeanewEarth.HoweverGliese58IgistwentylightyearsfromtheEarth. 1Whatdoastronomershavetofindfirstbeforestartingtolookforanewplaceforhumanstolive? A.newstar. B.Anewplanet. C.Someheat. D.Somelight. 2Whatdoestherockonaplanettellus? A.Thestarisinarightposition. B.Wemaydiscoverwaterunderit. C.TheplanetistooneartotheSun. D.Therecanbeairaroundtherock. 3Whatdoestheunderlinedwordscrutinizingmeaninthelastparagraph? A.discussing. B.waiting. C.looking. D.traveling. 4What'sthemainideaofthetext? A.Gliese581gisalreadyanewEarth. B.ThereareplanetssimilartoourEarth. C.Waterairandrockareimportant. D.AstronomersarelookingforanewEarth.

TheboyfatherisateacherisgoodatEnglish.

若-2=1则括号内填的一个数应该是

研究电流跟电压的关系用如图所示的电路在保持电阻不变这一步骤实验要求是A．保持R'的滑片位置不动B．保持R两端的电压不变C．保持电路中的电流不变D．只调节R'的滑片到不同的适当位置

Hereapairofglovesforyoutowear.A.are B.is C.were D.be

已知函数fx＝lnx﹣x+aa∈R． 1若fx≤0恒成立求a的取值范围 2若gx＝fx﹣试研究gx的单调性 3若x1x2是函数fx的两个零点且x1＜x2求证x1x2＜1．

设△ABC的内角ABC所对边分别为abc若a＝3b＝A＝则B＝

一幼儿园有10个班每个班有30名同学每个班同学随机编号为01﹣30为了了解他们家长对幼儿园管理方面的要求对每班第19号同学的家长进行调查这里运用的抽样方法是

如图所示A为地球同步卫星B为在地球赤道平面内运动的圆轨道卫星AB绕地心转动方向相同已知B卫星轨道运行周期为2小时图示时刻A在B正上方则

如图甲所示矩形导线框abcd固定在匀强磁场中磁场的方向与导线框所在的平面垂直磁感应强度B随时间变化的规律如图乙所示规定垂直纸面向里为磁场正方向顺时针方向为感应电流i正方向水平向右为ad边所受安培力F的正方向．下列图象正确的有

根据下列条件作圆以定点O为圆心作圆使其过另一个定点P

Mymotherdoesn'twantmetomoreweight.A.putup B.puton C.putoff D.putaway

已知数列{an}中a1＝1前n项的和为Sn且满足数列{}是公差为1的等差数列． 1求数列{an}的通项公式 2若恒成立求λ的取值范围．

ThisistheshirtIboughtyesterday.

某物体质量为1kg在水平拉力作用下沿粗糙水平地面做直线运动其速度﹣时间图象如图所示根据图象可知

已知函数fx＝+x3+sinx其导函数为f′x则f2020+f′2020+f﹣2020﹣f′﹣2020的值为

实数xy满足则z＝y﹣4x的取值范围是．

计算-56×-32+-46×32

在[﹣11]上随机取一个数k则事件直线y＝kx与圆x﹣132+y2＝25相交发生的概率为

Thisisthehouseinmygrandfatheroncelived. A.where B.that C.whose D.which

Whichisyoursister?She'sthegirliswearingthegreendress. A.who B.whose C.which D.what

在△ABC中abc分别为角ABC的对边若bcosC＝ccosB若b＝2且cosA＝则a的值为

﹣WhereisMike? ﹣IsawhimwithMr.Smithinthehallwaysjustnow. A.totalk B.talking C.talked D.talks

Susanwantstohernewfriendstoherbirthdayparty.

Thepriceoffooddrinksandclothessoquicklytheseyears.A.develops B.speed C.space D.increases

静止于粗糙水平面上的物体受到方向恒定的水平拉力F的作用其大小随时间变化如图甲所示．在拉力F从零逐渐增大的过程中物体的加速度随时间变化如图乙所示g取10m/s2．则下列说法中错误的是

我国古代数学家赵爽的弦图是由四个全等直角三角形与一个小正方形拼成的一个大正方形如图．如果小正方形的面积为1大正方形的面积为25直角三角形中较小的锐角为θ那么cos2θ的值等于