人教版 八年级下 期末专题复习(综合填空)含答案
人教版八年级下册英语期末完形填空专题练习(含答案)
人教版八年级下册英语期末完形填空专题练习(含答案)一、完形填空阅读下面短文,然后从各题所给的四个选项中选出一个最佳答案。
One day, a little boy asked his father, "What does the word "great' mean? Who are great people and 1.do they become great?"The father asked his son to bring two plants and then told him to plant one of them 2.the house and the other outside the house. The boy did as his father said.The father asked his son, "Which one of the two plants do you think will be 3.? The boy replied, "The plant inside the house will grow bigger 4.it is safer, while the plant outside the house is not safe at all. No one will be there to 5.the plant. Animals may eat it. "The father smiled and said, "Let's wait 6.We will know the answer."Then the boy left for study and after four 7.he came back to his house. He said to his father, "Look, 8.happens to this plant inside the house and it is safe."When the boy went outside, he was very 9.to see a big tree. The boy couldn't believe his eyes. He couldn't 10.how the plant outside was able to grow much bigger than the one inside. "The plant outside the house faced every 11.and many difficulties!" the father told his son why the plant outside was bigger. "The plant inside was safe. It didn't 12.weather changes. And it didn't get enough 13., so it didn't become big. "How to be great? Here's the 14.: To become a great person, one must have 15.many times, faced many difficulties and solved those difficulties. Only after that he is abie to become great. 1.A.how B.what C.when D.where 2.A.beside B.opposite C.inside D.outside 3.A.prettier B.bigger C.taller D.greener4.A.if B.though C.before D.because5.A.care for B.laugh at C.take away D.cut down6.A..recently B.patiently C.quickly D.carefully 7.A.days B.weeks C.months D.years 8.A.something B.nothing C.everything D.anything 9.A.upset B.surprised C.relaxed D.interested 10.A.decide B.accept C.understand D.remember11.A.wall B.corner C.season D.person 12.A.stop B.break C.cause D.experience 13.A.food B.water C.warmth D.sunlight 14.A.key B.result C.meaning D.example 15.A.failed B.travelled C.considered D.succeeded完形填空Mom's eyesight was worse and worse, but I didn't know how bad it was. I didn't know it until one day I saw her 16.something off the floor. She could hardly see it so she tried hard but 17.. I saw what was happening.Mother is in her late 70s, but she still 18.alone in the countryside. We haven't lived together since I left for college. She is always telling us that she really enjoys living a 19.life there. But it's 20.that she doesn't want to make me into trouble in my busy life, because she thinks we are unlike in so many ways.I felt 21.these days because of Mother's eyeproblem. I decided to 22.my job and take care of my mother at home."You know," Mom advised me, "losing my sight isn't so bad, but losing your 23.is terrible. So you have to work. I'm OK."A few weeks before Christmas Mother 24.in a quiet way. Only then did I know that Mother had serious heart disease. She didn't tell me the 25.because she just wanted me to concentrate on work.16.A.finding out B.playing with C.picking up D.taking care of 17.A.agreed B.accepted C.achieved D.failed 18.A.works B.eats C.lives D.plays19.A.quiet B.busy C.free D.relaxing 20.A.interesting B.true C.lucky D.unforgettable 21.A.happy B.worried C.comfortable D.amazed 22.A.stop B.get C.find D.change23.A.life B.hobby C.family D.job24.A.slept B.walked C.died D.ended 25.A.address B.truth C.dream D.wish阅读下面短文,掌握其大意,然后从每题所给的A、B、C、D四个选项中选出最佳选项。
人教版八年级英语下册期末试卷(含答案)
八年级下册期末试卷英语一、知识运用(共20小题, 计20分)第一节语法填空从A、B、C三个选项中选出最佳答案填空(共10小题, 计10分)1.—With everybody’s hard work, more Chinese people understand the importance of sortingwaste.—An.the.ar.bette.a.i.now._______.hug.th.progres.is!A.Ho.B.Wha..C.What2.________ Chinese culture, many college students go to foreign countries every year.A.Sprea.B.T.sprea.C.Spreading3.—I think that man must be Bob.—I._______.b.him.H.ha._______.t.Australia.A.can’t.gon.B.mustn’t.bee.C.can’t.been4.After the new high-speed railway started, the time on the trip from Lianyungang to Qingdao ismuch less than ________ in the past.A.on.B.thi.C.that5.________ I came into this room, I found him ________ on the bed asleep.A.While.li.B.When.lyin.C.When.t.lie6.Th.populatio.o.Chin._______.large.Fou.fifth.o.th.populatio._______.farmers.A.is.i.B.is.ar.C.are.is7.—Tom hardly depends on his parents.—________.Bot.o.yo.ar.s.independent.A.Neithe.d.yo.B.Neithe.ar.yo.C.S.d.you8.______they left early for the airport, they nearly missed the flight.A.A.soo.a.B.Althoug.C.If9.—Have you _______ that 5G network is on the way?—Yes, our teacher ______ us about it three months ago.A.hear.ha.tol.B.heard.tol.C.heard.ha.told10.—I wondered ________.—They did it by working with a group.A.ho.h.ha.finishe.th.bookin.examC.ho.the.wil.leav.fo.Paris二、语言运用(满分15分)第一节(共10小题, 每小题1.5分, 计15分)阅读下面的短文, 从短文后各题所给的A.B.C三个选项中, 选出可以填入空白的最佳答案。
人教版八年级下期末复习综合练习题(含答案)
期末复习综合练习题一.选择题(满分40分,每小题4分)1.下列各组数据不是勾股数的是()A.2,3,4 B.3,4,5 C.5,12,13 D.6,8,10 2.式子有意义的x的取值范围是()A.x≥﹣且x≠1 B.x≠1 C.D.x>﹣且x≠1 3.如图,菱形ABCD的两条对角线AC,BD相交于点O,E是AB的中点,若AC=6,BD=8,则OE长为()A.3 B.5 C.2.5 D.44.对于一次函数y=(k﹣3)x+2,y随x的增大而增大,k的取值范围是()A.k<0 B.k>0 C.k<3 D.k>35.下列各式中计算正确的是()A.=×=(﹣2)×(﹣4)=8B.=4a(a>0)C.=3+4=7D.=6.为了比较甲乙两足球队的身高谁更整齐,分别量出每人身高,发现两队的平均身高一样,甲、乙两队的方差分别是1.7、2.4,则下列说法正确的是()A.甲、乙两队身高一样整齐B.甲队身高更整齐C.乙队身高更整齐D.无法确定甲、乙两队身高谁更整齐7.如图,在▱ABCD中,下列说法能判定ABCD是菱形的是()A.AC⊥BD B.BA⊥BD C.AB=CD D.AD=BC8.如图是一个运算程序的示意图,若输出y的值为2,则输入x的值可能为()A.3 B.±1 C.1或3 D.±1或3 9.《九章算术》是我国古代的数学名著,书中的“折竹抵地”问题:今有竹高一丈,末折抵地,去本三尺.问折者高几何?意思是:一根竹子,原高一丈(一丈=10尺),一阵风将竹子折断,其竹梢恰好抵地,抵地处离竹子底部3尺远,问折断处离地面的高度是多少?设折断后离地面的高度为x尺,则可列方程为()A.x2﹣3=(10﹣x)2B.x2﹣32=(10﹣x)2C.x2+3=(10﹣x)2D.x2+32=(10﹣x)210.如图,在长方形纸片ABCD中,AB=4,AD=6.点E是AB的中点,点F是AD边上的一个动点.将△AEF沿EF所在直线翻折,得到△GEF.则GC长的最小值是()A.B.C.2D.2二.填空题(每题4分,满分24分)11.计算结果为.12.若一次函数y=ax+b(a≠0)的图象经过(3,2)和(﹣3,﹣1)两点,则方程ax+b =﹣1的解为.13.在九年级体育考试中,某校某班参加仰卧起坐测试的8名女生成绩如下(单位:次/分):44,45,42,48,46,43,47,45,则这组数据的众数为.14.已知点P是正方形ABCD内部一点,且△PAB是正三角形,则∠CPD=度.15.如图,将▱ABCO放置在平面直角坐标系xOy中,O为坐标原点,若点A的坐标是(5,0).点C的坐标为(1,﹣3),则点B的坐标是.16.已知一次函数y=mx+n中,函数y与自变量x的部分对应值如下表:x…﹣2 ﹣1 0 1 2 …y…10 8 6 4 2 …则不等式mx+n>0的解集是.三.解答题17.(8分)计算:(1)(2).18.(8分)如图,E是▱ABCD的边CD的中点,延长AE交BC的延长线于点F.(1)求证:△ADE≌△FCE.(2)若∠BAF=90°,BC=5,EF=3,求CD的长.19.(8分)如图,在正方形网格中,每个小正方形的边长均为1,△ABC的三个顶点分别在正方形网格的格点上.(1)计算边AB、BC、AC的长.(2)判断△ABC的形状,并说明理由.20.(8分)为了解某校九年级男生在体能测试的引体向上项目的情况,随机抽取了部分男生引体向上项目的测试成绩,绘制出如下的统计图①和图②.请根据相关信息,解答下列问题:(Ⅰ)本次接受随机抽样调查的男生人数为,图①中m的值为;(Ⅱ)求本次调查获取的样本数据的平均数、众数和中位数;(Ⅲ)若规定引体向上6次及以上(含6次)为该项目良好,根据样本数据,估计该校320名九年级男生中该项目良好的人数.21.(8分)如图,△ABC中,∠ACB=90°,D是AB中点,过点B作直线CD的垂线,垂足为E,求证:∠EBC=∠A.22.(10分)如图,在直角坐标系中放入一个矩形纸片ABCO,BC=10,将纸片翻折后,点B恰好落在x轴上,记为B',折痕为CE,已知OC:OB'=4:3.(1)求点B'的坐标;(2)求折痕CE所在直线的解析式.23.(10分)商丘市梁园区紧紧围绕十九大报告提出的阶段性目标任务,深化农业供给侧结构性改革,调整种植结构,深入进行了四大结构调整,分别是:水池铺乡的辣椒产业、刘口乡的杂果基地,孙福集乡的山药、莲藕产业,双八镇的草莓产业.目前,这四种产业享誉省内外.某外地客商慕名来商丘考查,他准备购入山药和草莓进行试销,经市场调查,若购进山药和草莓各2箱共花费170元,购进山药3箱和草莓4箱共花费300元.(1)求购进山药和草莓的单价;(2)若该客商购进了山药和草莓共1000箱,其中山药销售单价为60元,草莓的销售单价为70元.设购进山药x箱,获得总利润为y元.①求y关于x的函数关系式;②由于草莓的保鲜期较短,该客商购进草莓箱数不超过山药箱数的,要使销售这批山药和草莓的利润最大,请你帮该客商设计一个进货方案,并求出其所获利润的最大值.24.(12分)如图,在正方形ABCD中,M、N分别是射线CB和射线DC上的动点,且始终∠MAN=45°.(1)如图1,当点M、N分别在线段BC、DC上时,请直接写出线段BM、MN、DN 之间的数量关系;(2)如图2,当点M、N分别在CB、DC的延长线上时,(1)中的结论是否仍然成立,若成立,给予证明,若不成立,写出正确的结论,并证明;(3)如图3,当点M、N分别在CB、DC的延长线上时,若CN=CD=6,设BD与AM的延长线交于点P,交AN于Q,直接写出AQ、AP的长.25.(14分)一次函数l1:y=ax+1与x轴交于E(﹣2,0),与y轴交于点A.l2:y=kx+b与x轴交于B(2,0),与y轴交于点D(0,﹣4).它们的图象如图所示,请依据图象回答以下问题:(1)a=;(2)确定l2的函数关系式;(3)求△ABC的面积.参考答案一.选择1.A.2.A.3.C.4.D.5.D.6.B.7.A.8.C.9.D.10.A.二.填空题11.x.12.x=﹣3.13.45.14.150.15.(6,﹣3)16.x<3.三.解答题17.解:(1)原式=﹣2﹣3=3﹣6﹣3=﹣6;(2)原式=2+2+1﹣=3+2﹣10=3﹣8.18.(1)证明:∵四边形ABCD是平行四边形,∴AD∥BC,AB∥CD,∴∠DAE=∠F,∠D=∠ECF,∵E是▱ABCD的边CD的中点,∴DE=CE,在△ADE和△FCE中,,∴△ADE≌△FCE(AAS);(2)∵△ADE≌△FCE,∴AE=EF=3,∵AB∥CD,∴∠AED=∠BAF=90°,在△ADE中,AD=BC=5,∴DE==4,∴CD=2DE=8.∴CD=2DE=8.19.解:(1)∵每个小正方形的边长都是1,∴AB==,BC==,AC==;(2)△ABC是等腰直角三角形,理由是:∵AB2+BC2=13+13=26,AC2=26,∴AB2+BC2=AC2,∵AB=BC=,∴△ABC是等腰直角三角形.20.解:(Ⅰ)接受随机抽样调查的男生人数=6+12+10+8+4=40(人),m%=×100%=25%,则m=25,故答案为:40;25;(Ⅱ)平均数=×(4×6+5×12+6×10+8×7+8×4)=5.8,众数是5,中位数是6;(Ⅲ)该校320名九年级男生中该项目良好的人数为:320×=176(人).21.解:∵∠ACB=90°,∴∠A+∠ABC=90°,又∵D是AB中点,∴,∴CD=BD,∴∠DCB=∠ABC,又∵∠E=90°,∴∠ECB+∠EBC=90°,∴∠EBC=∠A.22.解:(1)∵四边形OABC是矩形,∴∠AOC=90°,∵OC:OB'=4:3,∴B′C:OB′=5:3,∵B′C=BC=10,∴OB′=6,∴B′点的坐标为:(6,0);(2)将纸片翻折后,点B恰好落在x轴上的B′点,CE为折痕,∴△CBE≌△CB′E,故BE=B′E,CB′=CB=OA,由OB′=6,OC:OB'=4:3,∴OC=8,设AE=a,则EB′=EB=8﹣a,AB′=AO﹣OB′=10﹣6=4,由勾股定理,得a2+42=(8﹣a)2,解得a=3,∴点E的坐标为(10,3),点C的坐标为(0,8),设直线CE的解析式为y=kx+b,根据题意,得,解得,∴CE所在直线的解析式为y=﹣x+8.23.解:(1)设购进每箱山药的单价为x元,购进每箱草莓的单价为y元,根据题意得,解得,答:每箱山药的单价为40元,每箱草莓的单价为45元;(2)①由题意可得,y=(60﹣40)x+(70﹣45)(1000﹣x)=﹣5x+25000;②由题意可得,,解得:x≥750,又y=﹣5x+25000,k=﹣5<0,∴y随x的增大而减小,∴当x=750时,y达到最大值,即最大利润y=﹣5×750+25000=21250(元),此时1000﹣x=1000﹣750=250(箱),答:购进山药750箱,草莓250箱时所获利润最大,利润最大为21250元.24.解:(1)BM+DN=MN,理由如下:在MB的延长线上,截取BE=DN,连接AE,∵四边形ABCD是正方形,∴AB=AD,∠BAD=∠ABC=∠D=90°,∴∠ABE=90°=∠D,在△ABE和△ADN中,,∴△ABE≌△ADN(SAS),∴AE=AN,∠EAB=∠NAD,∴∠EAN=∠BAD=90°,∵∠MAN=45°,∴∠EAM=45°=∠NAM,在△AEM和△ANM中,,∴△AEM≌△ANM(SAS),∴ME=MN,又∵ME=BE+BM=BM+DN,∴BM+DN=MN;故答案为:BM+DN=MN;(2)(1)中的结论不成立,DN﹣BM=MN.理由如下:在DC上截取DF=BM,连接AF,则∠ABM=90°=∠D,在△ABM和△ADF中,,∴△ABM≌△ADF(SAS),∴AM=AF,∠BAM=∠DAF,∴∠BAM+∠BAF=∠BAF+∠DAF=∠BAD=90°,即∠MAF=∠BAD=90°,∵∠MAN=45°,∴∠MAN=∠FAN=45°,在△MAN和△FAN中,,∴△MAN≌△FAN(SAS),∴MN=NF,∴MN=DN﹣DF=DN﹣BM,∴DN﹣BM=MN.(3)AP=3.25.解:(1)∵一次函数l1:y=ax+1与x轴交于E(﹣2,0),∴﹣2a+1=0,解得a=,故答案为;(2)∵直线l2:y=kx+b与x轴交于B(2,0),与y轴交于点D(0,﹣4).∴,解得∴l2的函数关系式为y=2x﹣4;(3)解得,∴C(,),由一次函数l1:y=ax+1可知A(0,1),∴S△ABC=S△ADC﹣S△ABD=(1+4)×﹣(1+4)×2=.。
人教版八年级下册数学期末试卷综合测试卷(word含答案)
人教版八年级下册数学期末试卷综合测试卷(word 含答案)一、选择题1.要使式子﹣3x -有意义,则x 的值可以为( )A .﹣6B .0C .2D .π2.下列语句不能判定ABC 是直角三角形的是( )A .2220a b c +-=B .::3:4:5A BC ∠∠∠= C .::3:4:5a b c =D .A B C ∠+∠=∠3.如图,四边形ABCD 的对角线AC 、BD 相交于O ,下列判断正确的是( )A .若AC ⊥BD ,则四边形ABCD 是菱形B .若AC =BD ,则四边形ABCD 是矩形C .若AB =DC ,AD ∥BC ,则四边形ABCD 是平行四边形 D .若AO =OC ,BO =OD ,则四边形ABCD 是平行四边形4.为了丰富校园文化,学校艺术节举行初中生书法大赛,设置了10个获奖名额.结果共有21名选手进入决赛,且决赛得分均不相同.若知道某位选手的决赛得分,要判断它是否获奖,只需知道学生决赛得分的( ) A .平均数B .中位数C .众数D .方差5.如图,在△ABC 中,AC =6,AB =8,BC =10,点D 是BC 的中点,连接AD ,分别以点A ,B 为圆心,CD 的长为半径在△ABC 外画弧,两弧交于点E ,连接AE ,BE .则四边形AEBC 的面积为( )A .2B .3C .24D .366.如图,在平面直角坐标系上,直线y =34x ﹣3分别与x 轴、y 轴相交于A 、B 两点,将△AOB 沿x 轴翻折得到△AOC ,使点B 刚好落在y 轴正半轴的点C 处,过点C 作CD ⊥AB 交AB 于D ,则CD 的长为( )A.185B.245C.4 D.57.如图,在平行四边形ABCD上,尺规作图:以点A为圆心,AB的长为半径画弧交AD于点F,分别以点B、F为圆心,以大于12BF的长为半径画弧交于点P,作射线AP交BC于点E,连接EF.若12BF=,10AB=,则线段AE的长为()A.18 B.17 C.16 D.148.如图,在平面直角坐标系中,点A的坐标是(4,0),点B的坐标是(3,4),点P 是y轴正半轴上的动点,连接AP交线段OB于点Q,若△OPQ是等腰三角形,则点P的坐标是()A.(0,53)B.(0,43)C.(0,43)或(0,163)D.(0,53)或(0,163)二、填空题9.2x-x的取值范围为__________.10.如图,在菱形ABCD中,AC=6,BD=8,则菱形的面积等于 ___.11.图中阴影部分是一个正方形,则此正方形的面积为_______ .12.在平行四边形ABCD 中,AB =5,AD =3,AC ⊥BC ,则BD 的长为____.13.已知一次函数y=kx +b 图像过点(0,5)与(2,3),则该一次函数的表达式为_____. 14.如图,O 是矩形ABCD 的对角线AC 、BD 的交点,OM ⊥AD ,垂足为M ,若AB=8,则OM 长为_______.15.如图,将一块等腰直角三角板ABC 放置在平面直角坐标系中,90,ACB AC BC ∠=︒=,点A 在y 轴的正半轴上,点C 在x 轴的负半轴上,点B 在第二象限,AC 所在直线的函数表达式是22y x =+,若保持AC 的长不变,当点A 在y 轴的正半轴滑动,点C 随之在x 轴的负半轴上滑动,则在滑动过程中,点B 与原点O 的最大距离是_______.16.如图,矩形ABCD 中,AB=8,AD=5,点E 为DC 边上一个动点,把△ADE 沿AE 折叠,点D 的对应点D ’落在矩形ABCD 的对称轴上时,DE 的长为____________.三、解答题17.计算:(1)80205-+;+-.(2)(53)(53)18.由于过度采伐森林和破坏植被,我国部分地区频频遭受沙尘暴的侵袭.近日,A城气象局测得沙尘暴中心在A城的正西方向240km的B处,以每时12km的速度向北偏东60°方向移动,距沙尘暴中心150km的范围为受影响区域.(1)A城是否受到这次沙尘暴的影响?为什么?(2)若A城受这次沙尘暴影响,那么遭受影响的时间有多长?A B C均在格点上.19.如图,网格中的每个小正方形的边长为1,点、、(1)直接写出AC的长为___________,ABC的面积为_____;(2)请在所给的网格中,仅用无刻度的直尺作出AC边上的高BD,并保留作图痕迹.20.已知:如图,在Rt△ABC中,D是AB边上任意一点,E是BC边中点,过点C作CF∥AB,交DE的延长线于点F,连接BF、CD.(1)求证:四边形CDBF是平行四边形.(2)当D点为AB的中点时,判断四边形CDBF的形状,并说明理由.21.先化简,再求值:a+2-+,其中a=1007.12a a如图是小亮和小芳的解答过程.(1)的解法是错误的;(2)错误的原因在于未能正确地运用二次根式的性质:;(3)先化简,再求值:a+2269-+,其中a=﹣2018.a a22.某电商在线销售甲、乙、丙三种水果,已知每千克乙水果的售价比每千克甲水果的售价多3元,每千克丙水果的售价是每千克甲水果售价的2倍,用200元购买丙水果的数量是用80元购买乙水果数量的2倍.(1)求丙水果每千克的售价是多少元?(2)电商推出如下销售方案:甲、乙、丙三种水果搭配销售共7千克,其中乙水果的数量是丙水果数量的2倍,且甲、乙两种水果数量之和不超过丙水果数量的6倍.请直接写出按此方案购买7千克水果最少要花费元.23.如图1,以平行四边形的顶点O为坐标原点,以所在直线为x轴,建立平面直角坐标系,,D是对角线AC的中点,点P从点A出发,以每秒1个单位的速度沿AB方向运动到点B,同时点Q从点O出发,以每秒3个单位的速度沿x轴正方向运动,当点P到达点B时,两个点同时停止运动.(1)求点A的坐标.(2)连结PQ,AQ,CP,当PQ经过点D时,求四边形的面积.(3)在坐标系中找点F,使以Q、D、C、F为顶点的四边形是菱形,则点F的坐标为________.(直接写出答案)24.(1)[探究]对于函数y=|x|,当x≥0时,y=x;当x<0时,y=﹣x.在平面直角坐标系中画出函数图象,由图象可知,函数y=|x|的最小值是.(2)[应用]对于函数y =|x ﹣1|+12|x +2|.①当x ≥1时,y = ;当x ≤﹣2时,y = ;当﹣2<x <1时,y = . ②在平面直角坐标系中画出函数图象,由图象可知,函数y =|x ﹣1|+12|x +2|的最小值是 .(3)[迁移]当x = 时,函数y =|x ﹣1|+|2x ﹣1|+|3x ﹣1|+…+|8x ﹣1|取到最小值.(4)[反思]上述问题解决过程中,涉及了一些重要的数学思想或方法,请写出其中一种. 25.如图,已知平面直角坐标系中,1,0A 、()0,2C ,现将线段CA 绕A 点顺时针旋转90︒得到点B ,连接AB .(1)求出直线BC 的解析式;(2)若动点M 从点C 出发,沿线段CB 10,过M 作//MN AB 交y 轴于N ,连接AN .设运动时间为t 分钟,当四边形ABMN 为平行四边形时,求t 的值. (3)P 为直线BC 上一点,在坐标平面内是否存在一点Q ,使得以O 、B 、P 、Q 为顶点的四边形为菱形,若存在,求出此时Q 的坐标;若不存在,请说明理由. 26.如图1,ABC ∆中,CD AB ⊥于D ,且::2:3:4BD AD CD =; (1)试说明ABC ∆是等腰三角形;(2)已知Δ40ABC S =cm 2,如图2,动点M 从点B 出发以每秒1cm 的速度沿线段BA 向点A 运动,同时动点N 从点A 出发以相同速度沿线段AC 向点C 运动,当其中一点到达终点时整个运动都停止.设点M 运动的时间为t (秒). ①若DMN ∆的边与BC 平行,求t 的值;②在点N 运动的过程中,ADN ∆能否成为等腰三角形?若能,求出t 的值;若不能,请说明【参考答案】一、选择题 1.D 解析:D 【分析】根据二次根式有意义的条件列出不等式,解不等式即可. 【详解】解:由题意得:x ﹣3≥0, 解得:x ≥3,各个选项中,π符合题意, 故选:D . 【点睛】此题主要考查二次根式有意义的条件,解题的关键是熟知二次根式的性质.2.B解析:B 【分析】由勾股定理的逆定理,只要验证两小边的平方和等于最长边的平方或最大角是否是90°即可. 【详解】解:A 、由2220a b c +-=,可得222+=a b c ,故是直角三角形,不符合题意; B 、∵::3:4:5A B C ∠∠∠=,∴∠C =180°×575345=︒++,故不是直角三角形,符合题意;C 、32+42=52,能构成直角三角形,不符合题意;D 、∵∠A +∠B =∠C ,∴∠C =90°,故是直角三角形,不符合题意; 故选:B . 【点睛】本题考查勾股定理的逆定理的应用.判断三角形是否为直角三角形,已知三角形三边的长,只要利用勾股定理的逆定理加以判断即可.3.D解析:D【分析】根据平行四边形及特殊平行四边形的判定方法,对选项逐个判断即可. 【详解】解:A :对角线相互垂直平行四边形才是菱形,四边形ABCD 不一定是平行四边形,故选项错误,不符合题意;B :对角线相等的平行四边形才是矩形,四边形ABCD 不一定是平行四边形,故选项错误,不符合题意;C :一组对边相等,另外一组对边平行,不一定是平行四边形,还有可能是等腰梯形,故选项错误,不符合题意;D :对角线互相平分的四边形是平行四边形,故选项正确,符合题意; 故选D . 【点睛】此题考查了平行四边形的判定方法,熟练掌握平行四边形及特殊平行四边形的判定方法是解题的关键.4.B解析:B 【解析】 【分析】由于书法大赛设置了10个获奖名额,共有21名选手进入决赛,根据中位数的意义分析即可. 【详解】解:将21名选手进入决赛不同的分数按从小到大排序后,中位数及中位数之后的共有11个数,故只要知道自己的分数和中位数就可以知道是否获奖了, 故选B . 【点睛】本题主要考查中位数,以及相关平均数、众数、方差的意义,熟练掌握相关知识是解题的关键.5.D解析:D 【分析】根据勾股定理的逆定理求出90BAC ∠=,求出BD CD AD AE BE ====,根据菱形的判定求出四边形AEBD 是菱形,根据菱形的性质求出//AE BD ,求出1122ABE ABD ACD ABC S S S S ∆∆∆∆====,再求出四边形AEBC 的面积即可.【详解】 解:6AC =,8AB =,10BC =,222AB AC BC ∴+=,ABC ∆∴是直角三角形,即90BAC ∠=︒,点D 是BC 的中点,10BC =,5BD DC AD ∴===,即5BE AE BD AD ====,∴四边形AEBD 是菱形,//AE BC ∴,1116812222ABE ABD ACD ABC S S S S ∆∆∆∆∴====⨯⨯⨯=,∴四边形AEBC 的面积是12121236++=,故选:D . 【点睛】本题考查了勾股定理的逆定理,直角三角形斜边上的中线的性质,菱形的性质和判定,三角形的面积等知识点,解题的关键是能求出12ABE ABD ACD ABC S S S S ∆∆∆∆===是解此题的关键,注意:①如果一个三角形的两边a 、b 的平方和等于第三边c 的平方,那么这个三角形是直角三角形,②等底等高的三角形的面积相等.6.B解析:B 【解析】 【分析】利用一次函数图象上点的坐标特征可求出点A ,B 的坐标,在Rt △AOB 中,利用勾股定理可求出AB 的长,由折叠的性质可得出OC =OB ,进而可得出BC 的长,再利用面积法,即可求出CD 的长. 【详解】解:当x =0时,y =34×0﹣3=﹣3,∴点B 的坐标为(0,﹣3);当y =0时,34x ﹣3=0,解得:x =4,∴点A 的坐标为(4,0).在Rt △AOB 中,∠AOB =90°,OA =4,OB =3, ∴5AB = 由折叠可知:OC =OB =3, ∴BC =OB +OC =6.∵S △ABC =12BC •OA =12AB •CD , ∴245BC OA CD AB == 故选B . 【点睛】本题主要考查了一次函数与坐标轴的交点问题,折叠的性质,三角形的面积公式,勾股定理等等,解题的关键在于能够熟练掌握相关知识进行求解.7.C解析:C 【解析】 【分析】证明四边形ABEF 是菱形,得到OA=OE ,OB=OF =6,AE ⊥BF ,再在Rt △AOB 中由勾股定理求出OA 即可解决问题. 【详解】解:∵以点A 为圆心,AB 的长为半径画弧交AD 于点F , ∴AF=AB ,∵分别以点B 、F 为圆心,以大于12BF 的长为半径画弧交于点P ,作射线AP 交BC 于点E ,∴直线AE 是线段BF 的垂直平分线, 且AP 为∠F AB 的角平分线, ∴EF=EB ,∠F AE=∠BAE , ∵四边形ABCD 为平行四边形, ∴AD ∥BC ,∠F AE =∠AEB , ∴∠AEB =∠BAE , ∴BA =BE , ∴BA =BE=AF=FE , ∴四边形ABEF 是菱形; ∴AE ⊥BF ,OB =OF =6,OA =OE , ∴∠AOB =90°,在Rt △AOB 中:8AO =, ∴216AE AO ==, 故选:C . 【点睛】本题考查的是菱形的判定、垂直平分线、角平分线的尺规作图、勾股定理等相关知识点,掌握特殊四边形的判定方法及重要图形的尺规作图是解决本题的关键.8.C解析:C 【分析】利用待定系数法分别求出OB 、PA 的函数关系式,设(0,)P m ,4(,)3Q n n ,并由P 、Q 点坐标,可表示出OP 、OQ 和PQ ,根据△OPQ 是等腰三角形,可得OP OQ =或OP PQ =或OQ PQ =,则可得到关于m 的方程,求得m 的值,即可求得P 点坐标.【详解】解:设OB 的关系式为y kx =,将B (3,4)代入得:43k =, ∴43OB y x =, 设(0,)P m ,4(,)3Q n n , ∴OP m =,53OQ n =,PQ = 设PA 的关系式为y kx b =+,将(0,)P m ,(4,0)A 代入得:40b m k b =⎧⎨+=⎩, 解得4b m m k =⎧⎪⎨=-⎪⎩, ∴4PA m y x m =-+, 将4PA m y x m =-+,43OB y x =联立方程组得: 443PA OB m y x m y x ⎧=-+⎪⎪⎨⎪=⎪⎩, 解得12163Q m x n m==+, 若△OPQ 是等腰三角形,则有OP OQ =或OP PQ =或OQ PQ =,当OP OQ =时,53m n =,12163m n m =+, 即5123163m m m=⨯+, 解得43m =,则P 点坐标为(0,43), 当OP PQ =时,m =,12163m n m =+, 解得176m =-,不合题意,舍去, 当OQ PQ =时,根据等腰三角形性质可得:点Q 在OP 的垂直平分线上,12Q y OP =, ∴4132n m =,且12163m n m =+, 即412131632m m m ⨯=+, 解得163m =,则P 点坐标为(0,163)综上可知存在满足条件的点P,其坐标为(0,43)或(0,163).故选:C.【点睛】本题是一次函数的综合问题,考查了待定系数法、等腰三角形的性质等知识,掌握待定系数法与两点间的距离公式并注意分类讨论思想及方程思想的应用是解题的关键,综合性较强.二、填空题9.x≥2且x≠3【解析】【分析】0,且分子二次根式的被开方数非负,则可求得x的取值范围.【详解】由题意得:3020xx-≠⎧⎨-≥⎩,解不等式组得:x≥2且x≠3.故答案为:x≥2且x≠3.【点睛】本题是求使式子有意义的自变量的取值范围的问题,涉及二次根式的意义,分母不为零,不等式组的解法等知识;一般地,当式子为分式时,分母不为零;当式子中含有二次根式时,要求被开方数非负.10.24【解析】【分析】根据菱形的面积=对角线积的一半,可求菱形的面积.【详解】四边形ABCD是菱形,∴116824 22S AC BD=⋅=⨯⨯=.故答案为:24.【点睛】本题考查菱形的性质,解题的关键是熟练运用菱形的性质.11.36cm2【解析】【分析】利用勾股定理求正方形边长,从而求正方形的面积.【详解】6∴正方形的面积为:6²=36故答案为:36 cm 2.【点睛】本题考查勾股定理解直角三角形,题目比较简单,正确计算是解题关键.12.A 解析:213【分析】根据AC ⊥BC ,AB =5,AD =3,可以得到AC 的长,再根据平行四边形的性质,可以得到DE 和BE 的长,然后根据勾股定理即可求得BD 的长.【详解】解:∵四边形ABCD 是平行四边形,∴AD =BC ,∵AC ⊥BC ,AB =5,AD =3,∴∠ACB =90°,BC =3,∴AC =4,作DE ⊥BC 交BC 的延长线于点E ,∵AC ⊥BC ,∴AC ∥DE , 又∵AD ∥CE ,∴四边形ACED 是矩形,∴AC =DE ,AD =CE ,∴DE =4,BE =6,∵∠DEB =90°,∴BD 222264213BE DE ++=故答案为:213【点睛】本题考查了平行四边形的判定和性质、勾股定理,解答本题的关键是熟练掌握勾股定理. 13.y =-x +5【分析】由直线y =kx +b 经过(0,5)、(2,3)两点,代入可求出函数关系式.【详解】解:把点(0,5)和点(2,3)代入y =kx +b 得532b k b =⎧⎨=+⎩,解得:15k b =-⎧⎨=⎩,所以一次函数的表达式为y =-x +5,故答案为:y =-x +5.【点睛】此题主要考查了待定系数法求一次函数解析式,注意利用一次函数的特点,来列出方程组求解是解题关键.14.A解析:4【解析】【分析】根据三角形的中位线即可求解.【详解】∵O 是矩形ABCD 的对角线AC 、BD 的交点,∴O 是AC 中点,又OM ⊥AD ,AD ⊥CD ∴12∥OM CD ,又AB=CD=8 故OM=4故填:4【点睛】此题主要考查矩形的性质,解题的关键是熟知三角形中位线的性质.15.【分析】根据自变量与函数值得对应关系,可得A ,C 点坐标,根据勾股定理,可得AC 的长度;根据全等三角形的判定与性质,可得CD ,BD 的长,可得B 点坐标;首先取AC 的中点E ,连接BE ,OE ,OB ,可求【分析】根据自变量与函数值得对应关系,可得A ,C 点坐标,根据勾股定理,可得AC 的长度;根据全等三角形的判定与性质,可得CD ,BD 的长,可得B 点坐标;首先取AC 的中点E ,连接BE ,OE ,OB ,可求得OE 与BE 的长,然后由三角形三边关系,求得点B 到原点的最大距离.【详解】解:当x =0时,y =2x +2=2,∴A (0,2);当y =2x +2=0时,x =-1,∴C (-1,0).∴OA =2,OC =1,∴AC如图所示,过点B 作BD ⊥x 轴于点D .∵∠ACO +∠ACB +∠BCD =180°,∠ACO +∠CAO =90°,∠ACB =90°,∴∠CAO =∠BC D .在△AOC 和△CDB 中,AOC CDB CAO BCD AC CB ∠=∠⎧⎪∠=∠⎨⎪=⎩, ∴△AOC ≌△CDB (AAS ),∴CD =AO =2,DB =OC =1,OD =OC +CD =3,∴点B 的坐标为(-3,1).如图所示.取AC 的中点E ,连接BE ,OE ,OB ,∵∠AOC =90°,AC =5, ∴OE =CE =12AC =52, ∵BC ⊥AC ,BC =5,∴BE =22BC CE +=52, 若点O ,E ,B 不在一条直线上,则OB <OE +BE =5522, 若点O ,E ,B 在一条直线上,则OB =OE +BE =5522, ∴当O ,E ,B 三点在一条直线上时,OB 取得最大值,最大值为552+, 故答案为:552+.【点睛】此题考查了一次函数综合题,利用自变量与函数值的对应关系是求AC 长度的关键,又利用了勾股定理;求点B 的坐标的关键是利用全等三角形的判定与性质得出CD ,BD 的长;求点B 与原点O 的最大距离的关键是直角三角形斜边上的中线的性质以及三角形三边关系.此题难度较大,注意掌握辅助线的作法,注意掌握数形结合思想的应用.16.或【详解】分析:过点D′作MN ⊥AB 于点N ,MN 交CD 于点M ,由矩形有两条对称轴可知要分两种情况考虑,根据对称轴的性质以及折叠的特性可找出各边的关系,在直角△EMD′与△AND′中,利用勾股定理解析:52或533【详解】分析:过点D′作MN⊥AB于点N,MN交CD于点M,由矩形有两条对称轴可知要分两种情况考虑,根据对称轴的性质以及折叠的特性可找出各边的关系,在直角△EMD′与△AND′中,利用勾股定理可得出关于DM长度的一元二次方程,解方程即可得出结论.详解:过点D′作MN⊥AB于点N,MN交CD于点M,如图1、所示.设DE=a,则D′E=a.∵矩形ABCD有两条对称轴,∴分两种情况考虑:①当DM=CM时,AN=DM=12CD=12AB=4,AD=AD′=5,由勾股定理可知:22=3AD AN'-,∴MD′=MN-ND′=AD-ND′=2,EM=DM-DE=4-a,∵ED′2=EM2+MD′2,即a2=(4-a)2+4,解得:a=52;②当MD′=ND′时,MD′=ND′=12MN=12AD=52,由勾股定理可知:2253 =AD ND'-'∴53,∵ED′2=EM2+MD′2,即a2=53−a)2+(52)2,解得:53.综上知:DE=5253.故答案为52.. 点睛:本题考查了翻转变换、轴对称的性质、矩形的性质以及勾股定理,解题的关键是找出关于DM 长度的一元二次方程.本题属于中档题,难度不大,但在做题过程中容易丢失一种情况,解决该题型题目时,结合勾股定理列出方程是关键.三、解答题17.(1)3;(2)2【分析】(1)先把二次根式化为最简二次根式,然后合并即可;(2)利用平方差公式计算即可.【详解】解:(1)原式=(2)原式=5﹣3=2.【点睛】本题考查的是二次根式解析:(1)2)2【分析】(1)先把二次根式化为最简二次根式,然后合并即可;(2)利用平方差公式计算即可.【详解】解:(1)原式==(2)原式=5﹣3=2.【点睛】本题考查的是二次根式的加减运算,二次根式的混合运算,掌握利用平方差公式进行简便运算是解题的关键.18.(1)受影响,理由见解析;(2)15小时【分析】(1)过点作AC ⊥BM ,垂足为C ,在Rt △ABC 中,由题意可知∠ABC=30°,由此可以求出AC 的长度,然后和150km 比较大小即可判断A 城是否解析:(1)受影响,理由见解析;(2)15小时【分析】(1)过点作AC ⊥BM ,垂足为C ,在Rt △ABC 中,由题意可知∠ABC =30°,由此可以求出AC 的长度,然后和150km 比较大小即可判断A 城是否受到这次沙尘暴的影响;(2)如图,设点E 、F 是以A 为圆心,150km 为半径的圆与BM 的交点,根据勾股定理可以求出CE 的长度,也就求出了EF 的长度,然后除以沙尘暴的速度即可求出遭受影响的时间.【详解】解:(1)过点A 作AC ⊥BM ,垂足为C ,在Rt △ABC 中,由题意可知∠CBA =30°,∴AC =12AB =12×240=120,∵AC =120<150,∴A 城将受这次沙尘暴的影响.(2)设点E ,F 是以A 为圆心,150km 为半径的圆与MB 的交点,连接AE ,AF , 由题意得,222221*********CE AE AC =-=-=,CE =90∴EF =2CE =2×90=180180÷12=15(小时)∴A 城受沙尘暴影响的时间为15小时.【点睛】本题考查了直角三角形中30°的角所对的直角边等于斜边的一半及勾股定理的应用,正确理解题意,把握好题目的数量关系是解决问题的关键.19.(1),;(2)见解析【解析】 【分析】(1)根据勾股定理和三角形的面积公式即可得到结论;(2)根据无刻度直尺作图中作垂直的技巧画出线段BD 即可;【详解】解:(1),:(2)如图所示,解析:(1)29AC =9ABC S=;(2)见解析【解析】【分析】(1)根据勾股定理和三角形的面积公式即可得到结论;(2)根据无刻度直尺作图中作垂直的技巧画出线段BD 即可;【详解】解:(1)222529,AC +, 111452425149222ABC S =⨯-⨯⨯-⨯⨯-⨯⨯=:(2)如图所示,BD 即为所求.【点睛】本题考查了作图-应用与设计作图,三角形的面积的计算,勾股定理,正确的作出图形是解题的关键.20.(1)见解析;(2)四边形CDBF 是菱形,理由见解析【分析】(1)证△CEF ≌△BED (ASA ),得CF=BD ,再由CF ∥DB ,即可得出结论; (2)由直角三角形斜边上的直线性质得CD=DB ,即解析:(1)见解析;(2)四边形CDBF 是菱形,理由见解析【分析】(1)证△CEF ≌△BED (ASA ),得CF =BD ,再由CF ∥DB ,即可得出结论;(2)由直角三角形斜边上的直线性质得CD =DB ,即可证平行四边形CDBF 是菱形.【详解】(1)证明:∵CF ∥AB ,∴∠ECF =∠EBD ,∵E 是BC 中点,∴CE =BE ,在△CEF 和△BED 中,ECF EBD CE BECEF BED ∠=∠⎧⎪=⎨⎪∠=∠⎩∴△CEF ≌△BED (ASA ),∴CF =BD ,又∵CF ∥AB ,∴四边形CDBF 是平行四边形.(2)解:四边形CDBF 是菱形,理由如下:∵D 为AB 的中点,∠ACB =90°,∴CD =12AB =BD ,由(1)得:四边形CDBF 是平行四边形,∴平行四边形CDBF 是菱形.【点睛】本题考查了平行四边形的判定和性质、菱形的判定、全等三角形的判定和性质、直角三角形斜边上的中线性质等知识;熟练掌握平行四边形的判定与性质,证明△CEF ≌△BED 是解题的关键,属于中考常考题型.21.(1)小亮(2)=-a (a <0)(3)2024.【解析】【详解】试题分析:(1)根据二次根式的性质=|a|,判断出小亮的计算是错误的; (2)错误原因是:二次根式的性质=|a|的应用错误;(解析:(1)小亮(2(a <0)(3)2024.【解析】【详解】试题分析:(1,判断出小亮的计算是错误的;(2的应用错误;(3)先根据配方法把被开方数配成完全平方,然后根据正确的性质化简,再代入计算即可. 试题解析:(1)小亮(2(a <0)(3)原式=a+2(3-a )=6-a=6-(-2018)=2024.22.(1)10;(2)46【分析】(1)设每千克甲水果的售价是元,则每千克乙水果的售价是元,每千克丙水果的售价是元,利用数量总价单价,结合用200元购买丙水果的数量是用80元购买乙水果数量的2倍,即解析:(1)10;(2)46【分析】(1)设每千克甲水果的售价是x 元,则每千克乙水果的售价是(3)x +元,每千克丙水果的售价是2x 元,利用数量=总价÷单价,结合用200元购买丙水果的数量是用80元购买乙水果数量的2倍,即可得出关于x 的分式方程,解之经检验后即可得出结论;(2)设搭配方案中含丙水果m 千克,则含乙水果2m 千克,甲水果(72)m m --千克,根据甲、乙两种水果数量之和不超过丙水果数量的6倍,即可得出关于m 的一元一次不等式,解之即可得出m 的取值范围,设购买7千克水果的费用为w 元,利用总价=单价⨯数量,即可得出w 关于m 的函数关系式,再利用一次函数的性质即可解决最值问题.【详解】解:(1)设每千克甲水果的售价是x 元,则每千克乙水果的售价是(3)x +元,每千克丙水果的售价是2x 元, 依题意得:80200232x x⨯=+, 解得:5x =,经检验,5x =是原方程的解,且符合题意,3538x ∴+=+=,22510x =⨯=.答:每千克丙水果的售价是10元.(2)设搭配方案中含丙水果m 千克,则含乙水果2m 千克,甲水果(72)m m --千克, 依题意得:7226m m m m --+,解得:1m .设购买7千克水果的费用为w 元,则5(72)82101135w m m m m m =--+⨯+=+.110>,w ∴随m 的增大而增大,∴当1m =时,w 取得最小值,最小值1113546=⨯+=(元).故答案为:46.【点睛】本题考查了分式方程的应用、一元一次不等式的应用以及一次函数的应用,解题的关键是:(1)找准等量关系,正确列出分式方程;(2)根据各数量之间的关系,找出w 关于m 的函数关系式.23.(1);(2)21;(3)或或或【分析】(1)过点作轴于,求出AH 和OH 即可;(2)证明≌,表示出AP ,CQ ,根据OC=14求出t 值,得到AP ,CQ ,再根据面积公式计算;(3)由Q 、D 、C 、解析:(1);(2)21;(3)或或或【分析】(1)过点A 作轴于H ,求出AH 和OH 即可; (2)证明≌,表示出AP ,CQ ,根据OC =14求出t 值,得到AP ,CQ ,再根据面积公式计算;(3)由Q 、D 、C 、F 为顶点的四边形是菱形得到以C ,D ,Q 为顶点的三角形是等腰三角形,求出CD ,得到点Q 坐标,再分情况讨论.【详解】解:(1)过点A 作轴于H , ∵,,, ∴, ∴A 点坐标为.(2)∵,∴C点坐标为,∵点D是对角线AC的中点,∴点D的坐标为,∵四边形ABCD是平行四边形,∴,∴,当PQ经过点D时,,在和中,,∴≌,∴,∵,∴,∴,∴,∴四边形APCQ的面积为,即当PQ经过点D时,四边形APCQ的面积为21.(3)∵F是平面内一点,以Q,D,C,F为顶点的四边形是菱形,则以C,D,Q为顶点的三角形是等腰三角形,∵,,∴,∴当时,Q点坐标为或,当Q点坐标为时,F点坐标为,当Q点坐标为时,F点坐标为,当时,点F与点D关于x轴对称,∴点F的坐标为,当时,设Q点坐标为,∴,解得,∴Q点坐标为,∴F点坐标为,∴综上所述,以Q,D,F,C为顶点的四边形是菱形,点F的坐标为或或或.【点睛】本题考查了平行四边形的性质,全等三角形的判定和性质,菱形的性质,等腰直角三角形的判定和性质,综合性较强,解题的关键是根据菱形的性质进行分类讨论.24.(1)见解析;0;(2)①x,﹣x,﹣x+2,②见解析;;(3);(4)分段去绝对值.【解析】【分析】(1)画出函数图象,直接得出结论;(2)先去绝对值,得出函数关系式,再画出函数图象,即可解析:(1)见解析;0;(2)①32x,﹣32x,﹣12x+2,②见解析;32;(3)16;(4)分段去绝对值.【解析】【分析】(1)画出函数图象,直接得出结论;(2)先去绝对值,得出函数关系式,再画出函数图象,即可得出结论;(3)分段去绝对值,合并同类项,得出函数关系式,即可得出结论;(4)直接得出结论.【详解】解:(1)[探究]图象如图1所示,函数y=|x|的最小值是0,故答案为0;(2)[应用]①当x≥1时,y=x﹣1+12(x+2)=32x;当x≤﹣2时,y=﹣x+1﹣12(x+2)=﹣32x;当﹣2<x<1时,y=﹣x+1+12(x+2)=﹣12x+2;②函数图象如图2所示,由图象可知,函数y=|x﹣1|+12|x+2|的最小值是32,故填:①32x,﹣32x,﹣12x+2,②32;(3)[迁移]当x≤18时,y=﹣x+1﹣2x+1﹣3x+1﹣4x+1﹣5x+1﹣6x+1﹣7x+1﹣8x+1=﹣36x+8,∴y≥72,当18<x≤17时,y=﹣x+1﹣2x+1﹣3x+1﹣4x+1﹣5x+1﹣6x+1﹣7x+1+8x﹣1=﹣20x+6,∴227≤y<72,当17<x≤16时,y=﹣x+1﹣2x+1﹣3x+1﹣4x+1﹣5x+1﹣6x+1+7x﹣1+8x﹣1=﹣6x+4,∴3≤y<227,当16<x≤15时,y=﹣x+1﹣2x+1﹣3x+1﹣4x+1﹣5x+1+6x﹣1+7x﹣1+8x﹣1=6x+2,∴3<y≤165,当15<x≤14时,y=﹣x+1﹣2x+1﹣3x+1﹣4x+1+5x﹣1+6x﹣1+7x﹣1+8x﹣1=16x,∴165<y≤4,当14<x≤13时,y=﹣x+1﹣2x+1﹣3x+1+4x﹣1+5x﹣1+6x﹣1+7x﹣1+8x﹣1=24x﹣2,∴4<y≤6,当13<x≤12时,y=﹣x+1﹣2x+1+3x﹣1+4x﹣1+5x﹣1+6x﹣1+7x﹣1+8x﹣1=30x﹣4,∴6<y≤11,当12<x≤1时,y=﹣x+1+2x﹣1+3x﹣1+4x﹣1+5x﹣1+6x﹣1+7x﹣1+8x﹣1=34x﹣6,∴11<y≤28,当x>1时,y=x﹣1+2x﹣1+3x﹣1+4x﹣1+5x﹣1+6x﹣1+7x﹣1+8x﹣1=36x﹣8,∴y>28,∴当x=16时,函数y=|x﹣1|+|2x﹣1|+|3x﹣1|+…+|8x﹣1|取到最小值;(4)[反思]用到的数学思想有:数形结合的数学思想,分段去绝对值,故答案为:分段去绝对值.【点睛】此题主要考查了一次函数的应用,去绝对值,函数图象的画法,用分类讨论的思想解决问题是解本题的关键.25.(1);(2)t=s时,四边形ABMN是平行四边形;(3)存在,点Q坐标为:或或或.【分析】(1)如图1中,作BH⊥x轴于H.证明△COA≌△AHB(AAS),可得BH=OA=1,AH=OC=2解析:(1)123y x=-+;(2)t=23s时,四边形ABMN是平行四边形;(3)存在,点Q坐标为:618,55⎛⎫⎪⎝⎭或(3,1)-或(3,1)-或155,88⎛⎫-⎪⎝⎭.【分析】(1)如图1中,作BH⊥x轴于H.证明△COA≌△AHB(AAS),可得BH=OA=1,AH=OC=2,求出点B坐标,再利用待定系数法即可解决问题.(2)利用平行四边形的性质求出点N的坐标,再求出AN,BM,CM即可解决问题.(3)如图3中,当OB为菱形的边时,可得菱形OBQP,菱形OBP1Q1.菱形OBP3Q3,当OB为菱形的对角线时,可得菱形OP2BQ2,点Q2在线段OB的垂直平分线上,分别求解即可解决问题.【详解】(1)如图1中,作BH⊥x轴于H.∵A(1,0)、C(0,2),∴OA=1,OC=2,∵∠COA=∠CAB=∠AHB=90°,∴∠ACO+∠OAC=90°,∠CAO+∠BAH=90°,∴∠ACO=∠BAH,∵AC=AB,∴△COA≌△AHB(AAS),∴BH=OA=1,AH=OC=2,∴OH=3,∴B(3,1),设直线BC的解析式为y=kx+b,则有231 bk b=⎧⎨+=⎩,解得:132k b ⎧=-⎪⎨⎪=⎩, ∴123y x =-+; (2)如图2中,∵四边形ABMN 是平行四边形,∴AN ∥BM ,∴直线AN 的解析式为:1133y x =-+, ∴10,3N ⎛⎫ ⎪⎝⎭, ∴103BM AN ==, ∵B (3,1),C (0,2),∴BC=10,∴2103CM BC BM =-=, ∴21021033t =÷=, ∴t=23s 时,四边形ABMN 是平行四边形; (3)如图3中,如图3中,当OB 为菱形的边时,可得菱形OBQP ,菱形OBP 1Q 1.菱形OBP 3Q 3, 连接OQ 交BC 于E ,∵OE⊥BC,∴直线OE的解析式为y=3x,由3123y xy x=⎧⎪⎨=-+⎪⎩,解得:3595xy⎧=⎪⎪⎨⎪=⎪⎩,∴E(35,95),∵OE=OQ,∴Q(65,185),∵OQ1∥BC,∴直线OQ1的解析式为y=-13x,∵OQ1,设Q1(m,-1m3),∴m2+19m2=10,∴m=±3,可得Q1(3,-1),Q3(-3,1),当OB为菱形的对角线时,可得菱形OP2BQ2,点Q2在线段OB的垂直平分线上,易知线段OB的垂直平分线的解析式为y=-3x+5,由3513y xy x=-+⎧⎪⎨=-⎪⎩,解得:15858xy⎧=⎪⎪⎨⎪=-⎪⎩,∴Q2(158,58-).综上所述,满足条件的点Q坐标为:618,55⎛⎫⎪⎝⎭或(3,1)-或(3,1)-或155,88⎛⎫-⎪⎝⎭.【点睛】本题属于一次函数综合题,考查了平行四边形的判定和性质,菱形的判定和性质,一次函数的性质等知识,解题的关键是灵活运用所学知识解决问题,学会用分类讨论的思想思考问题,属于中考压轴题.26.(1)证明见解析;(2)①t值为5或6;②点N运动的时间为6s,,或时,为等腰三角形. 【分析】(1)设BD=2x,AD=3x,CD=4x,则AB=5x,由勾股定理求出AC,即可得出结论;(2解析:(1)证明见解析;。
人教版八年级物理下册期末综合素质评价含答案
期末综合素质评价一、选择题(每题3分,共36分)1.如图是小明参加足球赛射门的情景,在射门过程中()A.脚对球施加了力,而球对脚没有力的作用B.球受的重力的方向始终水平向前C.球离开脚后继续向前运动是因为球具有惯性D.球的运动状态始终不变2.某同学推着购物车在超市购物。
下列分析正确的是()A.购物车受到的总重力和支持力是一对相互作用力B.人推着购物车前行时,人相对于货物架是静止的C.购物车从静止到运动的过程中,车中的某个商品惯性变大了D.商品从货物架放入购物车的过程中,商品的运动状态发生了改变3.下列做法是为了减小摩擦的是()A.下雪天,汽车轮胎套上防滑链B.拔河比赛中用力抓紧拔河绳C.给自行车的轮轴上加润滑油D.轮胎的表面做得凹凸不平4.有这样一个实验:将一根绳子穿过内壁和端口光滑的空心圆筒,绳子上端系一个金属球,下端与装有皮球的网袋连接。
转动空心圆筒,使金属球转动(如图)。
随着转速加大,网袋由静止开始向上运动。
下列判断正确的是()A.网袋静止时,它受到的总重力与它对绳子的拉力是一对平衡力B.金属球转动过程中,它受到的重力与绳子对它的拉力是一对平衡力C.金属球转动过程中,运动状态不变D.实验表明,改变物体的运动状态需要力5.如图所示,在探究二力平衡的条件时,选质量为10 g的卡片作为研究对象。
在线的两端分别挂上等质量的重物,对卡片施加两个拉力。
为探究这两个力满足什么条件才能平衡,则所挂重物质量合适的是()A.5 gB.10 gC.200 gD.任意质量均可6.以下四个增大压强的情境中,所用方法与另外三个不同的是() A.盲道上有凸起的小圆点B.菜刀刀刃很锋利C.压路机的碾子很重D.注射器的针头很尖7.下列所示的各种力学现象中,分析正确的是()8.网上流传着一种说法,通过鸡蛋能否沉入水底可以鉴别其是否新鲜。
为了验证其真实性,小亮买了些新鲜鸡蛋,并拿其中一枚进行实验。
第一天放入水中的鸡蛋沉入水底(如图甲),取出鸡蛋擦干放置50天后,再放入水中时鸡蛋漂浮在水面上(如图乙),看来网传是真的。
人教版八年级物理下册期末综合素质评价含答案
人教版八年级物理下册期末综合素质评价一、选择题(每题3分,共36分)1.踢足球是广大青少年喜爱的运动,下列与踢球有关的说法正确的是()A.踢球时,脚对球施加了力,球对脚没有力的作用B.只要脚对球施加的力大小相同,其作用效果一定相同C.踢出去的球在空中运动的过程中,没有受到任何力的作用D.守门员使球停下来的过程中,力改变了球的运动状态2.如图是小明在玩过山车的情景。
下列对此过程中小明的状况叙述正确的是()A.质量不断改变B.运动方向不变C.受到重力的方向始终竖直向下D.在运动中始终处于二力平衡状态3.汽车停放在水平路面上,下列属于平衡力的是()A.汽车受到的重力和地球对汽车的引力B.汽车受到的重力和汽车对路面的压力C.汽车受到的重力和路面对汽车的支持力D.路面对汽车的支持力和汽车对路面的压力4.日常生活中经常需要增大或减小摩擦,下列实例中,为了增大摩擦的是() A.给自行车的车轴处加润滑油B.汽车轮胎表面凹凸不平的花纹C.缝衣针的表面做得很光滑D.为了移动重物,在它下面垫上圆柱形钢管5.下列现象中不是利用大气压工作的是()A.用塑料吸盘挂物体B.用塑料吸管吸饮料C.用注射器将药液注入病人体内D.用活塞式抽水机抽水6.图中利用连通器原理工作的是()7.如图所示,在水平桌面上放置一个装有适量水的锥形瓶,瓶内漂浮着一块冰,冰熔化过程中()A.瓶内水面上升B.水对瓶底的压强减小C.桌面受到的压力增大D.桌面受到的压强不变8.在平南高铁站,离站台边缘一定距离的地方标有一条安全线,人必须站在安全线以内的区域候车,以免发生危险,这主要是因为高速列车经过时,列车与人之间的()A.空气流速增大,压强减小B.空气流速减小,压强减小C.空气流速增大,压强增大D.空气流速减小,压强增大9.如图所示,将一枚鸡蛋放在一杯盐水中,鸡蛋刚好处于悬浮状态,在往杯中加入清水的过程中,下列判断正确的是()A.鸡蛋将上浮,在未露出水面之前,所受浮力在减小B.鸡蛋将上浮,在未露出水面之前,所受浮力不变C.鸡蛋将下沉,所受浮力在减小D.鸡蛋将下沉,所受浮力不变10.荡秋千时人从最高点向最低点摆动过程中,速度变大,则他的() A.重力势能增加,动能不变B.重力势能不变,动能增加C.重力势能减小,动能增加D.重力势能减小,动能减小11.如图甲所示,木块放在水平面上,用弹簧测力计沿水平方向拉木块使其做直线运动,两次拉动木块得到的s-t关系图象如图乙所示。
人教版八年级英语下册期末综合检测卷含答案
人教版八年级英语下册期末综合检测卷(限时: 100分钟满分: 120分)一、单项选择(每小题1 分, 共10 分)1. Peter is ________ honest boy and ________ good friend of mine.A. a; theB. the; anC. a; anD. an; a2. —Did you hear any strange ________ when the earthquake happened?—No, I was in my garden with my flowers and enjoying the beautiful ________ of my birds at that time.A. voice; noiseB. sound; noiseC. whisper; noiseD. sound; voice3. We’ve got no coffee. Let’s have tea ________.A. eitherB. alreadyC. yetD. instead4. —China’s high-speed railway ________ is leading the world.—That’s right.A. technologyB. environmentC. populationD. agriculture5. The population of China ________ large. About four fifths of the population________ farmers.A. is; areB. are; isC. are; areD. is; be6. What a ________ boy! He worked out such a difficult math problem.A. strongB. kindC. lazyD. clever7. [2023 宿迁] —China won all the gold medals at the 2023 World Table TennisChampionships!—________ exciting news!A. What aB. How aC. HowD. What8. [2023 天津] Lisa is a popular monitor. She ________ her classmates and teachers.A. takes part inB. gets on well withC. gets into trouble withD. keeps clear of9. [2023 武汉武昌区期中] It’s everyone’s job to ________ a clean and comfortableenvironment in the classroom ________ students.A. provide; withB. offer; toC. provide; toD. offer; /10. Each of the students in my class ________ the museum at least twice.A. have gone toB. have been toC. has gone toD. has been to二、[原创题] 完形填空(每小题1 分, 共10 分)A merchant (商人) went to the market and there he saw a fine camel. After a long bargain(讨价还价) with the owner of the camel, he bought it for a good 11 .On reaching home, the merchant began to 12 the camel. Suddenly, he found a small cloth bag which was hidden under the saddle (鞍). When he opened it, he was 13 to find that it was filled with expensive diamonds and jewels (钻石和珠宝).“I have bought a camel, and I14 for the camel not for diamonds. I must return it immediately. ”Soon he hurriedly returned to the market to find the man from whom he bought that camel.Soon, the merchant found him and returned him the 15 .The man was delighted to see that bag and said, “Thank you so much for r eturning it. You can choose any one diamond from the bag as a reward. ”The merchant replied, “I don’t need any16 and reward for returning this. ”As much as the merchant was 17 , the man was still insisting (坚持)!At last the merchant smiled and s aid, “In fact, when I decided to bring back the bag, I had already kept the most 18 thing out of it!”After listening to this, the man became so angry that he emptied the bag to count his diamonds and jewels! But 19 was there.“There is not even one missing from the bag. 20 what was the most expensive thing you got from it?” asked the man in surprise.The merchant said, “Oh, it’s honesty. ”11. A. price B. day C. time D. place12. A. help B. sell C. climb D. feed13. A. afraid B. lucky C. excited D. surprised14. A. looked B. asked C. paid D. served15. A. bag B. animal C. money D. cloth16. A. promise B. thanks C. prize D. advice17. A. inviting B. introducing C. refusing D. explaining18. A. expensive B. useful C. beautiful D. popular19. A. nothing B. something C. everyone D. everything20. A. So B. While C. And D. Or三、阅读理解(每小题2 分, 共50 分)A21. What does Raven think of the amount of their homework?A. Unfair.B. Necessary.C. Terrible.D. Acceptable.22. How long does it take Robin to finish his homework every day?A. About 15 minutes.B. About 30 minutes.C. About 45 minutes.D. About an hour.23. How often do Polish students make a presentation in class?A. Always.B. Often.C. Sometimes.D. Never.24. For which subject does Nina get thought-provoking projects?A. Math.B. English.C. Chemistry.D. Physics.25. The passage mainly tells us ________.A. how teachers give lessons in other countriesB. what students’ homework is like in other countriesC. what subjects are offered to students in other countriesD. what after-school activities students have in other countriesBIt was Saturday again. Lily and Lucy disliked Saturdays. That was another thing the twins had in common. They shared the same clothes and tied their hair in the same manner. In fact, it was hard for their classmates and teachers to tell them apart sometimes.Unlike their classmates, they had to get up early at seven every Saturday to prepare for their lessons. Lily had to attend the art lesson and Lucy had to attend her ballet lesson. “How I wish I could do something different today, ” said the twins with one voice. All at once, an idea came to Lily and Lucy at the same time. “Do you have the same idea as mine?” they asked each other and laughed. It seemed like a wonderful plan to them. After giving each other a description of their own friends, Lily put on Lucy’s ballet dress while Lucy put Lily’s brushes and paints into her bag. Then they left for their classes.When the art lesson started, Lucy couldn’t understand the art teacher. Unlike Lily, Lucy was po or at drawing. When the art lesson finally ended, Lucy didn’t dare to hand in her work.Meanwhile, Lily was struggling in the ballet class as well. As she had no idea about the dance steps, she had to follow her classmates blindly. As a result, she kept knocking into them. Their ballet teacher became impatient with her, “Lucy, you should remember the basic steps. You can’t depend on copying what others are doing. ”When Lily and Lucy arrived home, they were tired out. They decided that they would never try to be someone else that they were not.26. What was the twins’ plan?A. To have a day off.B. To be each other for a day.C. To wear the same clothes.D. To have a normal day like their classmates.27. How did Lucy feel at the beginning of the art lesson?A. Lost.B. Excited.C. Mad.D. Sleepy.28. What does the underlined word “them” refer to?A. The teachers.B. The classmates.C. The dance steps.D. The ballet dresses.29. The ballet teacher became impatient because _______.A. she w asn’t herself that dayB. “Lucy” wasn’t patient that dayC. “Lucy” did very badly that dayD. she had discovered the twins’ plan30. What did the twins learn from the experience?A. Don’t try to run before you can walk.B. A good beginning makes a good ending.C. Saying is one thing and doing is another.D. The grass is not always greener on the other side.CThe Little Prince was written by a French pilot and writer Antoine de Saint-Exupéry. It is one of the most famous books around the world. It was published in 1943. _________ This story has been translated into 42 languages and was adapted into a movie.The little prince lives on a small planet alone. He leads a happy life. One day the winds bring him a seed. The seed then turns into the loveliest flower he has ever seen. He takes good care of the flower, but finally he decides to leave it and his planet to look for a secret —the most important thing in his life.During his journey in space, the little prince meets a king, a businessman, a lamplighter and a geographer. They all live alone on different planets. At last he finds out the secret from a fox of the Earth. Before he returns to his planet, he tells his secret to the writer of the book, whom he meets in the desert. The secret is: the power of love.When you read this touching and moving story of the little prince, you can’t help smiling and feeling the beauty of life and love in your heart.31. What does Antoine de Saint-Exupéry do?A. A prince.B. A writer and teacher.C. A pilot and writer.D. A bookseller.32. After reading the passage, we can’t know ________.A. who adapted the book into a movieB. when the book was publishedC. what the book is aboutD. who wrote the book33. Which of the following is TRUE according to the passage?A. The little prince met the writer of the book in the desert.B. The flower asked the little prince to look for the most important thing in hislife.C. The writer of the book told the little prince the secret.D. The secret is the power of knowledge.34. The underlined word “touching” means “________” in Chinese.A. 无聊的B. 感人的C. 惊讶的D. 失望的35. How many people are mentioned (提及) in the story introduction?A. Only one.B. Five.C. Six.D. Eight.DMario was a famous and successful businessman. Once he joined an important meeting. The office woman asked for his e-mail address. To her surprise, he didn’t have an e-mail address. “You don’t have an e-mail address, but you have such a big company. What you could be if you had an e-mail address? ” He replied, “An office man!” He told her the following story when he looked at her amazing face.When he was a young man, he lost his job and looked for one. In a newspaper he found a job of an office man and asked for it. The manager interviewed him and gave him a test. At last the manager said, “You pass the interview. Now give me your e-mail address so that I can send you further information and the joining letter. ” Mario said he didn’t have any e-mail address.The manager said, “What? If you have no e-mail address, that means you can’t live and can’t get this job. ”Mario didn’t know what to do as he had only 200 cents left. He didn’t want to go home without a job. He decided to go to the supermarket and buy 10 kg of vegetablesand then w ent door to door to sell them. He couldn’t sell out them until evening, but he made money two times of the money.This made him realize that he could make money through this. He went to the supermarket to buy fresh vegetables early in the morning every day and then sold them the whole day. He worked very hard and 5 years later he became successful. Then he had his own company.He said, “If we look for something and don’t get it, we shouldn’t lose hope and we should keep trying.”36. What did the office w oman feel when she knew Mario didn’t have an e-mailaddress?A. She felt excited.B. She felt angry.C. She felt amazed.D. She felt funny.37. Where did Mario know the information about the new job?A. On the Internet.B. In a magazine.C. In a book.D. In a newspaper.38. What did the manager mean in the third paragraph?A. He couldn’t give the job to Mario.B. He thought Mario was cheating him.C. He would give Mario an e-mail address.D. He planned to help Mario make more money.39. How much money did Mario have on the first selling evening?A. 200 cents.B. 300 cents.C. 400 cents.D. 600 cents.40. What’s the best title for the passage?A. We need to have our own ideaB. We should never lose our hopeC. We must learn to find a jobD. We can try many different jobsE [2023 珠海文园中学期中]Bamboo is one of nature’s most surprising plants. It is a kind of grass, thoughmany people call it a tree.Like other kinds of grass, although you cut it very low to the ground, it will grow back very quickly. A Japanese scientist recorded one bamboo plant that grew nearly 1.5 meters in 24 hours. Bamboo grows almost everywhere in the world except Europe. There are over 1,000 kinds of bamboo and they grow around the world on both mountains and plains (平原).Not all bamboo looks the same. Some bamboo plants are thick. They may grow to more than 30 centimeters across while others may only grow to be a few centimeters wide. They may also have different colors, like yellow, black and green.Bamboo is a kind of utility plant. Many Asian countries use it to make many things such as hats and kitchen tools. And it is used to build buildings or support new buildings and bridges. In fact, the cables that hold up the hanging bridge across the Min River in Sichuan are made of bamboo.In Africa, engineers are teaching poor farmers how to find water using bamboo. These farmers need cheap ways to water the fields because they have no money. Bamboo pipes (管子) can help them bring water to their thirsty fields without much money.41. How is bamboo like grass according to the passage?A. It is thin and easy to cut.B. It grows everywhere.C. It is short and green.D. It grows quickly after it’s cut short.42. We can infer (推断) from Paragraph 2 that _________.A. a bamboo plant may grow 4.5 meters in three daysB. the Japanese scientist is good at growing bamboo plantsC. bamboo is able to grow well in any part of the worldD. mountains are the best places for the bamboo to grow43. The underlined word “utility” in Paragraph 4 probably means _________.A. differentB. importantC. usefulD. colorful44. Why do the engineers teach the poor farmers in Africa to use bamboo?A. Because it is used by Asians.B. Because it is cheap.C. Because it is strong.D. Because it grows fast.45. According to the passage, which of the following is NOT true?A. There are many different kinds of bamboo in different colors.B. Some bamboo plants are thick, but others are thin.C. Bamboo can be used for buildings, bridges and watering.D. Engineers in Africa don’t want to spend money.四、词汇运用(每小题2 分, 共10 分)从方框中选择适当的单词或短语并用其正确形式填空。
2020年英语八年级下册期末复习综合检测试题 (含答案) (人教版)
2020春季学期八年级下册期末复习综合检测卷英语试题一、短语英汉互译。
(每小题1分,共10分)1.at the time of _____________2.die down _____________3.pick up ___________4.in a mess _____________5.at first __________6.(闹钟)发出响声_______________7.入睡,睡着____________ 8.拆倒,拆毁_________________9.沉默,无声_____________ 10.前往,到…去_______________二、单项选择。
(每小题1分,共20分)( )1. I’ve no pen ______ me. Would you lend one ____me?A. without, forB. with, toC. to, forD. for, to( )2. We‘re going to _____ many schools in the west of China.A. cheer upB. set upC. pull offD. put on( )3. Do you need to _____ a plan for your holiday?A. give outB. gave outC. give offD. come up with( )4. On weekends I like to _____at the English club with my friends.A. hang outB. look outC. hand outD. give out( )5. The lazy man has _____his money, so he has to borrow some money from others.A. use outB. ran outC. run out ofD. cost( )6.—?—I have a headache and I don’t feel l ike eating anything.A. How are you?B. What can I do for youC. What’s the matter with youD. How do you like it( )7. –Why are you so tired these days? --Well, I have ______ homework to doA. too muchB. too manyC. much tooD. many too( )8. Now, some robots are _______ to do the same things ______ peopleA. enough smart; asB. enough smart; forC. smart enough; asD. smart enough; with( )9. — I have too much housework to do at home.—ask your husband for help?A.You canB.Why don’tC.Why notD.How about( )10. —Alice fell down and hurt ___________ just now.—We should take ___________ to the hospital.A. her; sheB. herself; sheC. herself; herD. her; her( )11. _______ is difficult to work out the maths problem.A. ThisB. ThatC. ItD. Its( )12. We decided _______ at the end of this month.A. travelB. not start outC. to leaveD. going( )13. They have no paper_______.A. to writeB. to write withC. write on D .to write on( )14. Let him _______ a rest. I think he must be tired after the long walk.A. hasB. haveC. to haveD. having( )15. _______the computer is a problem.A. How to useB. What to useC. Where to useD. Which to use( )16. The teacher told us _______in bed.A. don’t readB. read notC. to not readD. not to read( )17. T he old man is used to __________ tea after he gets up.A. drinkB. drinksC. drinkingD. drank( )18. To my ____________, the square (广场) was so clean after the big meeting.A. surpriseB. surprisedC. surprisingD. surprises( )19. I________a lot but I don't play very often now.A. used to play tennisB. was used to play tennisC. am used to play tennisD. used to playing tennis( )20. Mr. Black walked around and offered help we were doing an experiment.A. whileB. althoughC. untilD. unless三、完型填空(共15小题,每小题1分,满分15分)阅读下面短文,从短文所给的A、B、C、D四个选项中,选出可以填入空白处的最佳选项"Hi!John." Mary ran towards me with a bright smile, saying, "I'm going to have a dance performance(表演)tonight. I hope you'll come. Here is the ticket. Don't forget!"Then she __1__ in a hurry."What? Dance? Is that __2__?"I asked myself. Mary was not such kind of girl. She was quite __3__ one. I had never seen her wearing colorful clothes. In fact, she really did not know __4__ to dress up. What a terrible thing!"I should go to, I must go to." I thought.I arrived at the hall with the ticket, found my __5__ and sat down. Her performance was the seventh one. I knew I would have a __6__ time before her turn, for I had no sense of art, __7__ her performance was worth watching, no matter how long I would wait.Time went __8__,I tried my best not to fall asleep.Just then, came the __9__,"Let's welcome the next exciting dance– Latin!"Hearing this, I opened my eyes as large as possible, __10__ to miss something. Wearing a golden and shining skirt, Mary appeared. She __11__ with a sweet smile, looking like a pretty butterfly flying…I could __12__ believe my eyes.After all the performance ended, I __13__ her at the gate."Hi!"She stood in front of me with her crystal(水晶)shoes. "How do you feel?""Fantastic!"I answered."Ha, ha. I knew __14__ would be."She could not hide her excitement, laughing __15__ a child.At that time, I realized that every girl has a pair of special shoes which are like the crystal shoes of Cinderella(灰姑娘).( )1. A. came B. jumped C. left D. moved( )2. A. possible B. lucky C. funny D. careful( )3. A. modern B. common C. perfect D. careful( )4. A. why B. where C. when D. how( )5. A. seat B. room C. gate D. way( )6. A. great B. short C. hard D. relaxing( )7. A. or B. so C. but D. and( )8. A. quickly B. slowly C. safely D. easily( )9. A. words B. sentences C. sounds D. cries( )10. A. hoping B. fearing C. planning D. hating( )11. A. walked B. skated C. danced D. stood( )12. A. seriously B. hardly C. nearly D. certainly( )13. A. waited for B. looked for C. paid for D. cared for( )14. A.I B. you C. she D. it( )15. A. as B. like C. for D. at四、阅读理解(共15小题,每小题2分,共30分)AWe drink tea every day. But more than three hundred years ago,most of the people in Europe did not knew anything about tea. Some people had heard about it,but very few of them knew what to do with it.There is a story about an English sailor(水手)who went to countries in the east,the west and the south. He had been to India(印度)and China. One day he came home and brought some tea as a present for his mother. She told her friends about the present and asked them to a“tea party”. When her friends come to the “tea party”,the old woman brought out some tea-leaves and asked them to eat. Of course,nobody like the tea-leaves.At that time the sailor came in. He looked at the table and said,“Mother,what have you done with the tea?”“I boiled(煮)it as you said. I threw it away,of course.”answered the old woman.“Now you may throw away the leaves,too.”said her son.( )1.Most of the people in Europe _________.A. drank tea every day 300 years agoB. drink tea every dayC. know nothing about teaD. like to eat tea leaves( )2.One day the sailor brought his mother some tea from _________.A. countries in the westB. countries in the southC. India or ChinaD. a tea shop in England( )3.The sailor's mother asked her friends to her house, because ________.A. the sailor told her toB. she wanted to ask her friends what to do with the teaC. she liked to show off (炫耀)D. she wanted to sample the tea together with her friends( )4.At the tea party, _________.A. all the woman's friends spoke highly of the teaB. nobody knew what to do with the teaC. the woman offered her friends some dried (干的) teaD. the woman gave her friends each a glass of tea water( )5.What mistake did the woman make?A. She boiled the tea.B. She did as the sailor said.C. She poured away the water.D. She didn't throw away the tea leaves.BPlants are very important. This is because plants can make food from air, water and sunlight. Animals and man can not make food from air, water and sunlight. Animals can get their food by eating plants and animals. Man gets his food by eating plants and animals, too. So animals and man need plants in order to live. This is why there are so many plants around us.There are two kinds of plants: flowering plants and non-flowering plants. You can know some trees from their flowers and fruits. Non-flowing plants do not grow flowers. You can not see many non-flowering plants around you.If you look carefully at the plants around us, you will find that there are many kinds of plants. Some plants are large and some are small. Most of them are green. Thanks to(多亏了)the plants around us we can live on the earth. ( )1. Which is the most important for the plants?A. flowerB. manC. animalsD. air, water and sunlight( )2. We need many plants around us because______.A. we can get what we need from the plantsB. plants are greenC. plants grow easilyD. we like all kind of plants( )3. There are _______non-flowering plants than flowering plants around us.A. much betterB. much fewerC. much moreD. much larger( )4. Most of the plants are __________.A. greenB. blackC. yellowD. white( )5. The best title(题目) is _________.A. Plants around usB. Food from plantC. Plants make foodD. Man and animalCAn exhausted(筋疲力尽的)looking woman came into the doctor’s office. She said, “Doctor, there are a lot of dogs all over my neighborhood. They bark(犬吠)all day and all night, and I can’t get a good sleep.”“I have good news for you,” the doctor said, taking out a small bottle. “Here are some new sleeping pills(安眠药)that work like a dream. A few of these and your trouble will be over.”“Great, thank you.” the woman was very glad to go back home with the pills.A few weeks later, the woman came again, looke d worse than ever. She said, “Doctor, your pills are not good at all. I’m more tired than before.”“I don’t understand how that could be,” said the doctor, shaking his head, “Those are the strongest pills on the market.”“That may be true,” answered the woman, “but I’m still up all night running after those dogs and when I finally catch one, it’s hard to get him to eat the pills.”( )1. The woman came to see the doctor because _____.A. her dog was illB. she was bitten(被咬)by dogsC. she couldn’t sleep wellD. her son was ill( )2. The doctor gave some pills to the woman for _____.A. the dogsB. herselfC. her sonD. her neighbors( )3. The woman got _____ in a few weeks.A. worseB. healthier `C. betterD. stronger( )4. Which of the following is RIGHT?A. The doctor gave the woman wrong pills.B. The woman liked to run with the dogs.C. The woman took the pills but the pills didn’t work at all.D. The woman might feel better if she took the pills.( )5. When he heard what the woman said, the doctor might think that _____.A. he gave the woman the right pillsB. the woman was a very clever personC. the woman was very foolish(愚蠢的)D. he should give the woman the pills again五、短文填空(共15小题,每小题1.5分,共15分)When you're busy or stressed, don't forget your hobbies, such as listening to (1________, reading and playing ball games.If eating makes you (2________ better, you can go to your favorite restaurant to (3________ a delicious meal.Parents may not think that it is (4________ to watch TV.(5________, if you are worried (6________ your English and don't know how to improve (7________, why not watch some English TV programs If you're feeling bad about your weight and don't know (8________ to do, why not go walking or jogging?Finally, trying to keep your worries to yourselves can make them worse.I like to share my problems with my friends.They always give me useful (9________.If you don't know who to talk to, you can always write (10________ me.You're never alone.六、书面表达(满分15分)你的生活和饮食习惯健康吗?请以“My Lifestyle”为题写一篇短文来介绍你的生活饮食习惯。
2023年新人教版八年级地理下知识点填空加读图复习期末含答案精选知识点期末
新人教版八年级地理下知识点填空加读图复习期末(含答案)精选“干旱”旳西北地区和“高寒”旳青藏地区对比第八章西北地区第一节自然特性与农业1、西北地区重要位于我国地势旳第二级阶梯, 大体位于大兴安岭以西、长城和昆仑山------阿尔金山以北。
(1)读西北地区图, 回答问题。
(2)邻国: ①蒙古②俄罗斯③哈萨克斯坦地形区: A大兴安岭山脉B河套平原C天山山脉D塔里木盆地E昆仑山脉F内蒙古高原2、(3)F高原东部旳植被类型以草原为主, D盆地则分布着我国最大旳沙漠塔克拉玛干沙漠。
3、西北地区旳地形以高原和盆地为主, 东部重要是内蒙古高原, 西部高山和盆地相间分布。
4、西北地区距海较远, 并且被山岭重重阻隔, 湿润气流难以抵达。
因此, 大部分地区年降水量在400mm如下。
5、西北地区气候干旱, 河流稀少多为季节性河流, 是我国内流河旳重要分布区, 我国最长旳内流河是塔里木河。
6、受降水旳影响, 西北地区植被景观自东向西依次是: 草原→荒漠草原→荒漠。
塔里木盆地中有我国面积最大旳沙漠——塔克拉玛干沙漠。
7、西北地区草场广布, 是我国重要旳畜牧业基地。
贺兰山以东地区降水较多, 地表水资源比较丰富, 分布有呼伦贝尔草原、锡林郭勒草原等大型优质草场, 贺兰山以西分布有高山草场。
8、西北地区只有在有河水、高山冰雪融水、地下水浇灌旳地区, 形成了浇灌农业区。
著名旳水利工程是坎儿井。
9、西北地区旳宁夏平原、内蒙古河套平原被誉“塞外江南”。
新疆旳长绒棉享誉全国。
读西北地区图回答:(1)山地: ①天山山脉②大兴安岭;盆地: ③准格尔盆地④塔里木盆地;都市: ⑤乌鲁木齐⑥呼和浩特;著名畜种: ⑦三河马、三河牛;(2)图中黑线标注边界线旳省(区)名称是内蒙古自治区;(3)从A到C干湿状况和植被类型分别是:A半湿润、森林草原B半干旱、草原C干旱、荒漠“干旱”旳西北地区和“高寒”旳青藏地区对比第八章西北地区第一节自然特性与农业西北地区重要位于我国地势旳第级阶梯, 大体位于以西、长城和---阿尔金山以北。
2023年人教版八年级数学下册期末考试题及答案【完美版】
2023年人教版八年级数学下册期末考试题及答案【完美版】 班级: 姓名:一、选择题(本大题共10小题,每题3分,共30分)1.已知31416181279a b c ===,,,则a b c 、、的大小关系是( )A .a b c >>B .a c b >>C .a b c <<D .b c a >>2.已知平行四边形ABCD ,下列条件中,不能判定这个平行四边形为矩形的是( )A .∠A=∠B B .∠A=∠C C .AC=BD D .AB ⊥BC3.一个正多边形的内角和为540°,则这个正多边形的每一个外角等于( )A .108°B .90°C .72°D .60°4. 20位同学在植树节这天共种了52棵树苗,其中男生每人种3棵,女生每人种2棵,设男生有x 人,女生有y 人,根据题意,列方程组正确的是( )A .523220x y x y +=⎧⎨+=⎩B .522320x y x y +=⎧⎨+=⎩C .202352x y x y +=⎧⎨+=⎩D .203252x y x y +=⎧⎨+=⎩5.已知直角三角形的两条边长分别是3和5,那么这个三角形的第三条边的长( )A .4B .16C .34D .4或346.如图,AB ∥CD ,点E 在线段BC 上,若∠1=40°,∠2=30°,则∠3的度数是( )A .70°B .60°C .55°D .50°7.如下图,下列条件中:①∠B+∠BCD=180°;②∠1=∠2;③∠3=∠4;④∠B=∠5,能判定AB ∥CD 的条件为( )A .①②③④B .①②④C .①③④D .①②③8.已知直线a ∥b ,将一块含45°角的直角三角板(∠C=90°)按如图所示的位置摆放,若∠1=55°,则∠2的度数为( )A .80°B .70°C .85°D .75°9.李大爷要围成一个矩形菜园,菜园的一边利用足够长的墙,用篱笆围成的另外三边总长应恰好为24米.要围成的菜园是如图所示的矩形ABCD .设BC 边的长为x 米,AB 边的长为y 米,则y 与x 之间的函数关系式是( )A .y=-2x+24(0<x<12)B .y=-x +12(0<x<24)C .y=2x -24(0<x<12)D .y=x -12(0<x<24)10.如图,直线,a b 被,c d 所截,且//a b ,则下列结论中正确的是( )A .12∠=∠B .34∠=∠C .24180∠+∠=D .14180∠+∠=二、填空题(本大题共6小题,每小题3分,共18分)1.如图,数轴上点A表示的数为a,化简:a244a a+-+=________.2.已知三角形ABC的三边长为a,b,c满足a+b=10,ab=18,c=8,则此三角形为__________三角形.3.分解因式6xy2-9x2y-y3 = _____________.4.如图是一个三级台阶,它的每一级的长、宽和高分别为20 dm,3 dm,2 dm ,A和B是这个台阶两个相对的端点,A点有一只蚂蚁,想到B点去吃可口的食物,则蚂蚁沿着台阶面爬到B点的最短路程是__________dm.5.如图,圆柱形玻璃杯高为14cm,底面周长为32cm,在杯内壁离杯底5cm的点B 处有一滴蜂蜜,此时一只蚂蚁正好在杯外壁,离杯上沿3cm与蜂蜜相对的点A处,则蚂蚁从外壁A处到内壁B处的最短距离为___________cm(杯壁厚度不计).6.如图,DE为△ABC的中位线,点F在DE上,且∠AFB=90°,若AB=6,BC =8,则EF的长为______.三、解答题(本大题共6小题,共72分)2.解方程组(1)43524x yx y+=⎧⎨-=⎩(2)12163213x yx y--⎧-=⎪⎨⎪+=⎩2.先化简,后求值:(a+5)(a ﹣5)﹣a(a﹣2),其中a=12+2.3.解不等式组20{5121123xx x->+-+≥①②,并把解集在数轴上表示出来.4.如图,A(4,3)是反比例函数y=kx在第一象限图象上一点,连接OA,过A作AB∥x轴,截取AB=OA(B在A右侧),连接OB,交反比例函数y=kx的图象于点P.(1)求反比例函数y=kx的表达式;(2)求点B的坐标;(3)求△OAP的面积.5.甲、乙两车分别从A、B两地同时出发,甲车匀速前往B地,到达B地立即以另一速度按原路匀速返回到A地;乙车匀速前往A地,设甲、乙两车距A地的路程为y(千米),甲车行驶的时间为x(时),y与x之间的函数图象如图所示(1)求甲车从A地到达B地的行驶时间;(2)求甲车返回时y与x之间的函数关系式,并写出自变量x的取值范围;(3)求乙车到达A地时甲车距A地的路程.6.某商店销售A型和B型两种电脑,其中A型电脑每台的利润为400元,B型电脑每台的利润为500元.该商店计划再一次性购进两种型号的电脑共100台,其中B型电脑的进货量不超过A型电脑的2倍,设购进A型电脑x台,这100台电脑的销售总利润为y元.(1)求y关于x的函数关系式;(2)该商店购进A型、B型电脑各多少台,才能使销售总利润最大,最大利润是多少?(3)实际进货时,厂家对A型电脑出厂价下调a(0<a<200)元,且限定商店最多购进A型电脑60台,若商店保持同种电脑的售价不变,请你根据以上信息,设计出使这100台电脑销售总利润最大的进货方案.参考答案一、选择题(本大题共10小题,每题3分,共30分)1、A2、B3、C4、D5、D6、A7、C8、A9、B10、B二、填空题(本大题共6小题,每小题3分,共18分)1、2.2、直角3、-y(3x-y)24、255、206、1三、解答题(本大题共6小题,共72分)1、(1)21xy=⎧⎨=-⎩;(2)53xy=⎧⎨=⎩.2、224-3、﹣1≤x<2.4、(1)反比例函数解析式为y=12x;(2)点B的坐标为(9,3);(3)△OAP的面积=5.5、(1)2.5小时;(2)y=﹣100x+550;(3)175千米.6、(1) =﹣100x+50000;(2) 该商店购进A型34台、B型电脑66台,才能使销售总利润最大,最大利润是46600元;(3)略.。
最新人教版八年级地理(下册)期末总复习及答案
最新人教版八年级地理(下册)期末总复习及答案(时间:60分钟分数:100分)班级:姓名:分数:一、选择题(共25个小题,每题2分,共50分)1、我国内流区域面积广大,内流河年径流总量不足全国的5%,关于我国内流河的叙述错误的是()A.汛期出现在冬季 B.多为季节性河流C.水源主要来自高山冰雪融水 D.通常水量随夏季气温增高而增加2、下列语句中,描写南方地区景观的是()A.千里冰封,万里雪飘B.枯藤老树昏鸦,小桥流水人家C.早穿皮袄午穿纱,围着火炉吃西瓜D.远看是山,近看成川3、关于三江源地区的说法,不正确的是( )A.位于西藏自治区南部 B.世界上海拔最高、面积最大的高原湿地C.被誉为“中华水塔” D.世界上高海拔地区生物多样性最集中的地区4、美国信息技术产业对经济发展的主要促进作用是( )①支柱产业,发展迅速②新增就业机会最大的产业部门③广泛应用于生产,促进了自然资源的开发和劳动密集型产业的发展④其他产业应用信息技术及其产品,明显提高生产效率、产品质量和价值A.②③④B.①③④C.①②④D.①②③5、我国最早建立的重工业基地位于下列哪个地区()A.西北地区B.北方地区C.南方地区D.青藏地区6、划分南北半球的界线是()A.20°W和160°E B.0°和180°C.0°纬线D.0°经线网7、下列地区与其美称对应关系正确的是()A.成都平原一“天府之国”B.四川盆地一“聚宝盆C.东北平原一“鱼米之乡”D.长江中下游平原一“黑土地”8、日本人20岁时,要举行“成人节”仪式,这时她们会穿上心爱的()A.唐装B.西装C.和服D.牛仔服9、下列说法指气候的是()A.夜来风雨声,花落知多少 B.昆明四季如春C.忽如一夜春风来,千树万树梨花开 D.风和日丽10、图中,①②③④地均位于大西洋两岸的陆地,则②大洲是()A.欧洲 B.南美洲 C.非洲 D.北美洲11、关于我国北方地区农业生产的叙述,错误的是()A.农田多为旱地,灌溉多采用水浇形式B.农作物有小麦、棉花、花生、甘蔗C.华北平原两年三熟或一年两熟D.东北地区一年一熟12、下图分别代表4种“土地类型的分布”,下列叙述与图中顺序相符的是()A.①水田②旱地③林地④荒地B.①水田②旱地③林地④草地C.①旱地②水田③荒地④草地D.①旱地②水田③荒地④林地13、我国的某山脉,以北以旱地为主,以南以水田为主,以北的耕作制度是两年三熟,以南的耕作制度是一年两熟,这条山脉是()A.天山B.阴山C.秦岭D.南岭14、有关人口分布的叙述,正确的是( )A.欧洲西部人口稠密B.亚洲内陆地区人口稠密C.凡是地势高的地区都是人口稠密地区D.世界上所有纬度低地区,人口都很稀少15、关于赤道的叙述,正确的是()A.东西半球的分界线B.南北半球的分界线C.东经和西经的分界线D.东经度和西经度的分界线16、我国少数民族主要分布的地区是()A.东北、西北、华北B.东北、西北、西南C.东北、东南、西南D.西北、西南、东南17、下列诗句中,形象地反映了我国北方地区冬季景观的是()A.“草长莺飞二飞二月天,拂堤杨柳醉春烟”B.“北国风光,千里冰封,万里雪飘”C.“羌笛何须招怨杨柳,春风不度玉门关”D.“君问归期未有期,巴山夜雨涨秋池”18、G20杭州峰会成为世界关注焦点。
人教版八年级化学(下册)期末复习及答案
人教版八年级化学(下册)期末复习及答案(时间:60分钟分数:100分)班级:姓名:分数:一、选择题(每小题只有1个选项符合题意。
共20小题,每题2分,共40分)1、碱式碳酸铜受热能分解成CuO、CO2和H2O三种物质,请你判断碱式碳酸铜的组成是()A.只含有碳、氢、氧元素B.一定含有碳、氢、铜元素,可能含有氧元素C.一定含有碳、氢、氧元素,可能含有铜元素D.肯定含有碳、氢、氧、铜元素2、下列叙述正确的是()A.化学反应过程中都会发生放热现象B.在化学反应中只有燃烧反应才能放出热量C.化学反应伴随着能量变化D.人类利用的能量都是通过化学反应获得的3、下图属“用后必须洗手”标志(贴在微毒或有毒的试剂瓶上)的是()A. B. C. D.4、取用粉末状固体化学药品时,应使用的仪器是()A.滴管B.研钵C.药匙D.镊子5、空气是人类宝贵的自然资源,下列有关空气的说法正确的是()A.洁净的空气是纯净物B.空气中的氧气可以供给呼吸、支持燃烧、炼钢、化工生产等C.分离液态空气得到氧气和氮气的过程中发生了化学反应D.新鲜空气中不含二氧化碳6、实验室制取气体选择收集方法时,下列气体性质不需考虑的是()A.密度B.可燃性C.溶解性D.能否与水反应7、硒元素具有抗衰老、抑制癌细胞生长的功能。
在硒的一种化合物硒酸钠(Na2SeO4)中,硒元素的化合价是()A.-3 B.+6 C.+4 D.+78、如图,将充满CO2的试管倒扣在滴有紫色石蕊的蒸馏水中,一段时间后,下列实验现象描述正确的是()①试管内液面上升②试管内溶液变红③试管内液面不上升④试管内溶液变蓝⑤试管内溶液不变色A.①②B.①④C.②③D.③⑤9、下列各图中和分别表示不同元素的原子,则其中表示化合物的是()A. B.C. D.10、化学反应前后肯定没有发生变化的是()①原子数目;②分子数目;③元素种类;④物质种类;⑤原子种类;⑥物质的总质量。
A.①④⑥B.①③⑤⑥ C.①②⑥ D.②③⑤11、“茉莉的香气清新淡雅,能够使人心情放松,檀木的香气持久醇厚,能缓解紧张焦虑的情绪……。
人教版数学八年级下册期末综合培优复习题(四)(含答案)
期末综合培优复习题(四)一.选择题(每题3分,满分36分)1.下列一定是二次根式的是()A.B.C.D.2.直线y=3x+1向下平移2个单位,所得直线的解析式是()A.y=3x+3 B.y=3x﹣2 C.y=3x+2 D.y=3x﹣13.如图,在四边形ABCD中,点P是边CD上的动点,点Q是边BC上的定点,连接AP,PQ,E,F分别是AP,PQ的中点,连接EF.点P在由C到D运动过程中,线段EF的长度()A.保持不变B.逐渐变小C.先变大,再变小D.逐渐变大4.已知n是一个正整数,是整数,则n的最小值是()A.3 B.5 C.15 D.455.有下列说法:①有一个角为60°的等腰三角形是等边三角形;②三边分别是1,,3的三角形是直角三角形;③直角三角形斜边上的中线等于斜边的一半;④三个角之比为3:4:5的三角形是直角三角形,其中正确的有()A.1个B.2个C.3个D.4个6.若a=1﹣,b=1+,则代数式的值为()A.2B.﹣2C.2 D.﹣27.有20个班级参加了校园文化艺术节感恩歌咏大赛,他们的成绩各不相同,其中李明同学在知道自己成绩的情况下,要判断自己能否进入前十名,还需要知道这十个班级成绩的()A.平均数B.加权平均数C.众数D.中位数8.已知直线y=x+b和y=ax﹣3交于点P(2,1),则关于x,y的方程组的解是()A.B.C.D.9.有一个面积为1的正方形,经过一次“生长”后,在他的左右肩上生出两个小正方形,其中,三个正方形围成的三角形是直角三角形,再经过一次“生长”后,变成了下图,如果继续“生长”下去,它将变得“枝繁叶茂”,请你算出“生长”了2019次后形成的图形中所有的正方形的面积和是()A.1 B.2018 C.2019 D.202010.在菱形ABCD中,∠ADC=120°,点E关于∠A的平分线的对称点为F,点F关于∠B的平分线的对称点为G,连结EG.若AE=1,AB=4,则EG=()A.2B.2C.3D.11.如图所示的图象(折线ABCDE)描述了一辆汽车在某一直线上的行驶过程中,汽车离出发地的距离s(千米)与行驶时间t(时)之间的函数关系,根据图中提供的信息,给出下列说法:①汽车共行驶了140千米;②汽车在行驶途中停留了1小时;③汽车在整个行驶过程中的平均速度为30千米/时;④汽车出发后6小时至9小时之间行驶的速度在逐渐减小.其中正确的说法共有()A.1个B.2个C.3个D.4个二.填空题(每题3分,满分18分)13.若点A (2,y 1),B (﹣1,y 2)都在直线y =﹣2x +1上,则y 1与y 2的大小关系是 . 14.使二次根式有意义的x 的取值范围是 .15.某公司招聘员工一名,某应聘者进行了三项素质测试,其中创新能力为70分,综合知识为80分,语言表达为90分,如果将这三项成绩按5:3:2计入总成绩,则他的总成绩为 分.16.已知一次函数y =kx ﹣3的图象与x 轴的交点坐标为(x 0,0),且2≤x 0≤3,则k 的取值范围是 .17.在平行四边形ABCD 中,连接AC ,∠CAD =40°,△ABC 为钝角等腰三角形,则∠ADC 的度数为 度.18.如图,过点N (0,﹣1)的直线y =kx +b 与图中的四边形ABCD 有不少于两个交点,其中A (2,3)、B (1,1)、C (4,1)、D (4,3),则k 的取值范围 .三.解答题 19.(6分)计算 (1)(3﹣2+)÷2 (2)×﹣(+)(﹣)20.已知一次函数y =(2m +1)x +3﹣m(1)若y 随x 的增大而减小,求m 的取值范围; (2)若图象经过第一、二、三象限,求m 的取值范围.21.(8分)为弘扬泰山文化,我市某校举办了“泰山诗文大赛”活动,小学、初中部根据初赛成绩,各选出5名选手组成小学代表队和初中代表队参加学校决赛.两个队各选出的5名选手的决赛成绩如下图所示.(1)根据图示填写图表;平均数(分)中位数(分)众数(分)小学部85初中部85 100 (2)结合两队成绩的平均数和中位数,分析哪个队的决赛成绩较好;(3)计算两队决赛成绩的方差并判断哪一个代表队选手成绩较为稳定.22.(6分)如图,在△ABC中,AD⊥BC,AB=15,AD=12,AC=13.求BC的长.23.(8分)如图,四边形ABCD中,对角线AC、BD相交于点O,AO=OC,BO=OD,且∠AOB =2∠OAD.(1)求证:四边形ABCD是矩形;(2)若∠AOB:∠ODC=4:3,求∠ADO的度数.24.(6分)已知y+m与x﹣n成正比例,(1)试说明:y是x的一次函数;(2)若x=2时,y=3;x=1时,y=﹣5,求函数关系式;(3)将(2)中所得的函数图象平移,使它过点(2,﹣1),求平移后的直线的解析式.25.(9分)为迎接“五一”国际劳动节,某商场计划购进甲、乙两种品牌的T恤衫共100件,已知乙品牌每件的进价比甲品牌每件的进价贵30元,且用120元购买甲品牌的件数恰好是购买乙品牌件数的2倍.(1)求甲、乙两种品牌每件的进价分别是多少元?(2)商场决定甲品牌以每件50元出售,乙品牌以每件100元出售.为满足市场需求,购进甲种品牌的数量不少于乙种品牌数量的4倍,请你确定获利最大的进货方案,并求出最大利润.参考答案一.选择题1. A .2. D .3. A .4. B .5. C .6. A .7. D .8. B .9. D 10. B .11. A . 二.填空题 13. y 1<y 2. 14. x ≤2. 15. 77. 16. 1≤k ≤. 17. 100或40. 18. <k ≤2. 三.解答题19.解:(1)原式=(9﹣+4)÷2=12÷2=6; (2)原式=﹣(5﹣3)=3﹣2 =1.20.解:(1)由2m +1<0,可得m <﹣, ∴当m <﹣时,y 随着x 的增大而减小; (2)由,可得﹣<m <3, ∴当﹣<m <3时,函数图象经过第一、二、三象限.21.解:(1)填表:小学部平均数 85( 分),众数85(分);初中部中位数 80( 分). 故答案为85,85,80.(2)小学部成绩好些.因为两个队的平均数都相同,小学部的中位数高,所以在平均数相同的情况下中位数高的小学部成绩好些.(3)∵=[(75﹣85)2+(80﹣85)2+(85﹣85)2+(85﹣85)2+(100﹣85)2]=70,,∴,因此,小学代表队选手成绩较为稳定.22.解:∵AD⊥BC,∴∠ADB=∠ADC=90°,∵AB=15,AD=12,AC=13,∴BD===9,CD===5,∴BC=BD+CD=9+5=14.23.(1)证明:∵AO=OC,BO=OD,∴四边形ABCD是平行四边形,∵∠AOB=∠DAO+∠ADO=2∠OAD,∴∠DAO=∠ADO,∴AO=DO,∴AC=BD,∴四边形ABCD是矩形;(2)解:∵四边形ABCD是矩形,∴AB∥CD,∴∠ABO=∠CDO,∵∠AOB:∠ODC=4:3,∴∠AOB:∠ABO=4:3,∴∠BAO:∠AOB:∠ABO=3:4:3,∴∠ABO=54°,∵∠BAD=90°,∴∠ADO=90°﹣54°=36°.24.解:(1)已知y+m与x﹣n成正比例,设y+m=k(x﹣n),(k≠0),y=kx﹣kn﹣m,因为k≠0,所以y是x的一次函数;(2)设函数关系式为y=kx+b,因为x=2时,y=3;x=1时,y=﹣5,所以2k+b=3,k+b=﹣5,解得k=8,b=﹣13,所以函数关系式为y=8x﹣13;(3)设平移后的直线的解析式为y=ax+c,由题意可知a=8,且经过点(2,﹣1),可有2×8+c=﹣1,c=﹣17,平移后的直线的解析式为y=8x﹣17.25.解:(1)设甲品牌每件的进价为x元,则乙品牌每件的进价为(x+30)元,,解得,x=30经检验,x=30是原分式方程的解,∴x+30=60,答:甲品牌每件的进价为30元,则乙品牌每件的进价为60元;(2)设该商场购进甲品牌T恤衫a件,则购进乙品牌T恤衫(100﹣a)件,利润为w元,∵购进甲种品牌的数量不少于乙种品牌数量的4倍,∴a≥4(100﹣a)解得,a≥80w=(50﹣30)a+(100﹣60)(100﹣a)=﹣20a+4000,∵a≥80,∴当y=80时,w取得最大值,此时w=2400元,100﹣a=20,答:获利最大的进货方案是:购进甲品牌T恤衫80件,购进乙品牌T恤衫20件,最大利润是2400元.。
人教版 八年级下 期末专题复习(首字母填空)含答案(1)
人教版八年级下期末专题复习首字母填空一、阅读下面文章,根据短文内容和所给单词的首字母提示填写合适的单词,补充文章内容。
Henry graduated from a famous university and found a good job in the bank. As he thought he was successful, he sometimes looked down on o___1___. He couldn't get on w___2___ with workmates and often made mistakes. Soon he was sent away. Then he found a job in a post office. He still couldn't change his attitude (态度). He couldn't be competent (能胜任的) at it and he had to leave. After he lost his jobs, his life got w___3___ than before. He was very w___4___ about his future. Luckily, a friend of his uncle's felt pity (可怜的) for him and a___5___ him to work in the restaurant. Of course, he didn't like the work at a___6___, but he had no choice but to a___7___ it. After he worked there two months, he gradually (逐渐的) liked the work and l___8___ much experience and was used to the life in the restaurant. During that time, the most important thing for him is that he r___9___ why he was not popular with others in the past and what he needs to do later. In fact, it's i___10___ for everyone to learn how to be polite.二、阅读下面文章,根据短文内容和所给单词的首字母提示填写合适的单词,补充文章内容。
人教版八年级下册物理期末复习《第7章力》-填空题专练(有答案)-解析板
人教版八年级下册物理期末复习第7章力填空题专练1.如图所示,一氢气球用细绳系在玩具车上,静置于广场的光滑水平地面上,当有匀速的风沿水平方向向右吹来,气球和玩具车在风力作用下向前运动,说明力能改变物体的运动状态;玩具车在向右运动的过程中不可能被风吹离地面;一段时间后玩具车匀速前进,此时细绳保持竖直(选填“向左倾斜”、“向右倾斜”或“保持竖直”)。
【考点】6F:力的作用效果.【分析】(1)力可以改变物体的形状,可以改变物体的运动状态;(2)风水平向右吹,玩具车在竖直方向上不受风的作用力;(2)物体处于平衡状态时,受平衡力作用,据此进行分析解答。
【解答】解:(1)当有匀速的风沿水平方向向右吹来,气球和玩具车在风力作用下向前运动,说明力能改变物体的运动状态;(2)风水平向右吹,玩具车在竖直方向上不受风的作用力,故玩具车在向右运动的过程中不可能被风吹离地面;(3)因水平地面光滑,所以玩具车在运动时不受摩擦力的作用;一段时间后玩具车在水平方向上匀速前进,若此时细绳是倾斜的,则细绳对玩具车有斜向上的拉力,导致玩具车受力不平衡,玩具车不可能做匀速运动,所以此时细绳应保持竖直。
故答案为:运动状态;右;保持竖直。
【点评】本题考查力的作用效果以及力的平衡条件的应用,难度不大,属于基础题。
2.如图所示,在皮划艇比赛时,发令枪响参赛选手奋力划桨,皮划艇由静止迅速前进,说明力可以改变物体的运动状态,向后划桨皮划艇向前运动说明物体间力的作用是相互的;此时以地面为参照物,皮划艇是运动的。
【考点】53:运动和静止的相对性;6F:力的作用效果;6I:力作用的相互性.【分析】(1)力的作用效果有两个:一是改变物体的形状,二是改变物体的运动状态;(2)力是物体对物体的作用,物体间力的作用是相互的;(3)判断运动还是静止需要选择一个参照物,然后来比较物体相对于参照物的位置有没有发生变化,发生变化就是物体相对于该参照物是运动的,否则就是静止的。
2020-2021年人教版英语 八年级英语下册完形填空专题复习练习(含解析)经典
2020-2021年人教版英语八年级英语下册完形填空专题复习练习(含解析)经典一、八年级英语下册完形填空专项练习(含答案解析)1.先通读下面的短文,掌握其大意,然后从A、B、C、D四个选项中选择可以填入空白处的最佳答案。
One night I saw something on the news that made me sad.It was 1 a group of homeless people sleeping outside in the cold.So I decided to start a 2 to raise money for the homeless.I called it the Rock Club.At the beginning,there were only five members in it,but that quickly grew to about twenty.I 3 had to ask anyone if they wanted to be a member.In fact,they came up to me and asked me if they could 4 the club!We spent all of our free time on rock painting.We painted animals, flowers and even the namesof sports teams on our rocks.We'd go around the school to 5 people who would buy them.By Christmas, we had raised thirty—three dollars andthen we gave the money to a homeless shelter(收容所) in town. We all felt 6 mat we could do something to help the homeless.A few days later, a newspaper reporter came to our school to 7 with us about our club and took a photo of us.The photo and article 8 in the newspaper the next ter, 9 school,joined by three other schools,started a program(方案)forkids to help homeless shelters.Something as 10 as some painted rocks and a few caring kids made me realize that I don't need much to make a difference.1. A. about B. with C. in D. at2. A. show B. club C. party D. magazine3. A. also B. even C. still D. hardly4. A. join B. report C. question D. believe5. A. kid B. find C. train D. change6. A. surprised B. happy C. nervous D. scared7. A. act B. read C. argue D. talk8. A. appeared B. copied C. compared D. imagined9. A. his B. her C. our D. their10. A. expensive B. strange C. hard D. simple【答案】(1)A;(2)B;(3)D;(4)A;(5)B;(6)B;(7)D;(8)A;(9)C;(10)D;【解析】【分析】这是一篇记叙文。
人教版 八年级数学下册 期末综合复习(含答案)
人教版 八年级数学下册 期末综合复习一、选择题(本大题共12道小题) 1. 计算(2x +1)(2x -1)的结果为 ( ) A .4x 2-1B .2x 2-1C .4x -1D .4x 2+12. 把分式方程2x +4=1x 转化为一元一次方程时,方程两边需同乘( ) A .xB .2xC .x +4D .x (x +4)3. 若a 2+ab +b 2=(a -b )2+X ,则整式X 为()A .abB .0C .2abD .3ab4. 如图,△ABE ≌△ACD ,∠A =60°,∠B =25°,则∠DOE 的度数为()A .85°B .95°C .110°D .120°5.(2020·临沂)如图,在ABC ∆中,AB AC =,40A ∠=︒,//CD AB ,则BCD ∠=( )A.40°B.50°C.60°.D.70°6. 下列哪一个度数可以作为某一个多边形的内角和 () A .240° B .600°C .540°D .2180°7. (2020·天津)计算221(1)(1)x x x +++的结果是( )A.11x+B.21(1)x+C. 1D. 1x+8. 如图,在△ABC中,AB=AC,以点C为圆心,CB长为半径画弧,交AB于点B和点D,再分别以点B,D为圆心,大于12BD长为半径画弧,两弧相交于点M,作射线CM交AB于点E.若AE=2,BE=1,则EC的长度是A.2 B.3C3D59. 下列长度的三条线段能组成钝角三角形的是( )A. 3,4,4B. 3,4,5C. 3,4,6D. 3,4,710.如图,平行河岸两侧各有一城镇P,Q,根据发展规划,要修建一条公路连接P ,Q两镇.已知相同长度造桥总价远大于陆上公路造价,为了尽量减少总造价,应该选择方案( )11. 如图为6个边长相等的正方形的组合图形,则∠1+∠2+∠3等于( )A.90°B.120 C.135°D.150°12.如图,在△CEF中,∠E=80°,∠F=50°,AB∥CF,AD∥CE,连接BC,CD ,则∠A的度数是( )A.45°B.50°C.55°D.80°二、填空题(本大题共12道小题)13.图中的虚线,哪些是图形的对称轴,哪些不是?是对称轴的是______;不是对称轴的是______.(填写序号)14. (2020·武威)分解因式:a2+a=.15.如图,已知在△ABC和△DEF中,∠B=∠E,BF=CE,点B,F,C,E在同一条直线上,若使△ABC≌△DEF,则还需添加的一个条件是________(只填一个即可).16.如图,两车从南北方向的路段AB的A端出发,分别向东、向西行进相同的距离,到达C,D两地,此时可以判断C,D到B的距离相等,用到的数学道理是____ ____.17.将两块完全相同的三角尺在∠AOB的内部如图摆放,两块三角尺较短的直角边分别与∠AOB的两边重合,且含30°角的顶点恰好也重合于点C,则射线OC即为∠AOB的平分线,理由是______________________.18.如图,∠AOB=40°,C为OB上的定点,M,N分别为OA,OB上的动点,当CM +MN的值最小时,∠OCM的度数为________.19. 将分式1a2-9和a3a-9进行通分时,分母a2-9可因式分解为____________,分母3a-9可因式分解为__________,因此最简公分母是____________.20. 若a-b=3x-y=2则a2-2ab+b2-x+y=________.21.如图,BO平分∠CBA,CO平分∠ACB,MN过点O且MN∥BC,设AB=12,AC =18,则△AMN的周长为________.22. 计算:1x2-6x+9÷x+3x-3·(9-x2).解:原式=1(x-3)2÷x+3x-3·(3+x)(3-x)……第一步=1(x-3)2·x-3x+3·(3+x)(3-x)……第二步=1.……第三步回答:(1)上述过程中,第一步使用的公式用字母表示为__________________________;(2)由第二步得到第三步所使用的运算方法是____________;(3)以上三步中,从第________步开始出现错误,本题的正确答案是__________.23. 一个等腰三角形的一边长是2,一个外角是120°,则它的周长是________.24. 画图:试画出下列正多边形的所有对称轴,并完成表格.根据上表,猜想正n边形有条对称轴.三、作图题(本大题共2道小题)25.利用刻度尺和三角尺作图:如图所示,已知四边形ABCD和直线m.请你作出四边形A1B1C1D1,使得四边形A1B1C1D1和四边形ABCD关于直线m成轴对称.26. 如图,在河岸l的同侧有两个居民小区A,B,现欲在河岸边建一个长为a的绿化带CD(宽度不计),使C到小区A的距离与D到小区B的距离之和最小.在图中画出绿化带的位置,并写出画图过程.四、解答题(本大题共6道小题)27. 如图,在△ABC中,AB边的垂直平分线DE分别与AB边和AC边交于点D 和点E,BC边的垂直平分线FG分别与BC边和AC边交于点F和点G,若△BEG 的周长为16,GE=3,求AC的长.28. 我们知道:分式和分数有着很多的相似点.如类比分数的基本性质,我们得到了分式的基本性质.小学时,把分子比分母小的分数叫做真分数.类似地,我们把分子的次数小于分母的次数的分式称为真分式,反之,称为假分式.对于任何一个假分式都可以化成整式与真分式的和的形式,如==+=1+. (1)下列分式中,属于真分式的是()A.B.C.-D.(2)将假分式化成整式与真分式的和的形式.29. 整体代入阅读下面文字,并解决问题.已知x2y=3,求2xy(x5y2-3x3y-4x)的值.分析:考虑到满足x2y=3的x,y的可能值较多,不可能逐一代入求解,故考虑整体思想,将x2y=3整体代入.解:2xy(x5y2-3x3y-4x)=2x6y3-6x4y2-8x2y=2(x2y)3-6(x2y)2-8x2y=2×33-6×32-8×3=2×27-6×9-8×3=-24.请你用上述方法解决问题:已知ab=3,求(2a3b2-3a2b+4a)·(-2b)的值.30.如图,已知AP∥BC,∠P AB的平分线与∠CBA的平分线相交于点E,过点E的直线分别交AP,BC于点D,C.求证:AD+BC=AB.31. 在△ABC中,∠A=90°,∠B=30°,AC=6 cm,点D从点A出发以1 cm/s的速度向点C运动,同时点E从点C出发以2cm/s的速度向点B运动,设运动时间为t s,解决以下问题:(1)当t为何值时,△DEC为等边三角形?(2)当t为何值时,△DEC为直角三角形?32. 已知有理数x ,y ,z 满足2|2|(367)|334|0x z x y y z --+--++-=,求3314n n n x y z x--的值.人教版 八年级数学下册 期末综合复习-答案一、选择题(本大题共12道小题) 1. 【答案】A2. 【答案】D3. 【答案】D4.【答案】C [解析]∵△ABE ≌△ACD ,∴∠B =∠C =25°.∵∠A =60°,∠C =25°,∴∠BDO =∠A +∠C =85°.∴∠DOE =∠B +∠BDO =85°+25°=110°.5. 【答案】D【解析】 根据三角形内角和定理和等腰三角形的等边对等角且AB AC =,40A ∠=,可得:70ABC ACB ∠=∠=;然后根据两直线平行内错角相等且//CD AB 可得:70BCD ABC ∠=∠=,所以选D .6. 【答案】C[解析] ∵多边形内角和公式为(n -2)×180°,∴多边形内角和一定是180°的倍数. ∵540°=3×180°,∴540°可以作为某一个多边形的内角和.7. 【答案】A【解析】本题考查分式的加减运算,主要运算技巧包括通分,约分,同时常用平方差、完全平方公式作为解题工具.本题可先通分,继而进行因式约分求解本题.221(1)(1)x x x +++21(1)x x +=+,因为10x +≠,故211=(1)1x x x +++.故选:A .8. 【答案】D【解析】由作法得CE ⊥AB ,则∠AEC=90°, AC=AB=BE+AE=2+1=3,在Rt △ACE 中,=.故选D .9.【答案】C【解析】①∵32+42=52,∴三条线段3、4、5组成直角三角形,∴B 选项不正确;②当把斜边5变成7时,3+4=7,不满足三角形两边之和大于第三边,不能构成三角形,∴D 选项不正确;③当把斜边5稍微变小一点为4时,三条线段为3、4、4组成锐角三角形,∴A 选项不正确;④当把斜边5稍微变大一点为6时,三条线段为3、4、6组成钝角三角形,∴C 选项正确.10.【答案】C [解析]如图,作PP′垂直于河岸L ,使PP′等于河宽,连接QP′,与河岸L 相交于点N ,将P′N 沿竖直方向向上平移河宽个单位长度,得到PM ,PM -MN -NQ 即所求.根据“两点之间,线段最短”,QP′最短,即PM +NQ 最短.观察选项,选项C 符合题意.11.【答案】C [解析]在图中容易发现全等三角形,将∠3转化为与其相等的对应角后可以看出∠3与∠1互余.故∠1+∠3=90°.易得∠2=45°,故∠1+∠2+∠3=135°.12. 【答案】B[解析] 如图,连接AC 并延长交EF 于点M.∵AB ∥CF ,∴∠3=∠1. ∵AD ∥CE ,∴∠2=∠4.∴∠BAD =∠3+∠4=∠1+∠2=∠FCE.∵∠FCE =180°-∠E -∠F =180°-80°-50°=50°,∴∠BAD =∠FCE =50°.二、填空题(本大题共12道小题)13. 【答案】②④⑥①③⑤14. 【答案】a 2+a =a (a +1).故答案为:a (a +1).15. 【答案】答案不唯一,如AB =DE[解析] ∵BF =CE ,∴BC =EF. 在△ABC 和△DEF 中,⎩⎪⎨⎪⎧AB =DE ,∠B =∠E ,BC =EF ,∴△ABC ≌△DEF(SAS).16. 【答案】线段垂直平分线上的点与这条线段两个端点的距离相等17. 【答案】角的内部到角的两边距离相等的点在角的平分线上18.【答案】10° [解析]作点C 关于OA 的对称点D ,过点D 作DN ⊥OB 于点N ,交OA 于点M ,则此时CM +MN 的值最小.∵∠OEC =∠DNC =90°,∠DME =∠OMN , ∴∠D =∠AOB =40°.∵MD=MC,∴∠DCM=∠D=40°,∠DCN=90°-∠D=50°.∴∠OCM=10°.19. 【答案】(a+3)(a-3)3(a-3)3(a+3)(a-3)20. 【答案】7[解析] a2-2ab+b2-x+y=(a-b)2-(x-y).把a-b=3x-y=2代入得原式=32-2=7.21. 【答案】30 [解析] ∵MN∥BC,∴∠MOB=∠OBC.∵∠OBM=∠OBC,∴∠MOB=∠OBM.∴MO=MB.同理NO=NC.∴△AMN的周长=AM+MO+AN+NO=AM+MB+AN+NC=AB+AC=30.22. 【答案】(1)a2-2ab+b2=(a-b)2,a2-b2=(a+b)(a-b)(2)约分(3)三-123. 【答案】 6 [解析] 已知三角形的一外角为120°,则相邻内角度数为60°,那么含有60°角的等腰三角形是等边三角形.已知等边三角形的一边长为2,则其周长为6.24. 【答案】解:如图.故填3,4,5,6,n.三、作图题(本大题共2道小题)25. 【答案】解:如图,四边形A1B1C1D1即为所求.26. 【答案】解:如图,作线段AP∥l,使AP=a,且点P在点A的右侧;作点P关于直线l的对称点P',连接BP'交l于点D;在l上点D的左侧截取DC=a,则CD就是所求绿化带的位置.四、解答题(本大题共6道小题)27. 【答案】解:∵DE垂直平分线段AB,GF垂直平分线段BC,∴EB=EA,GB=GC.∵△BEG的周长为16,∴EB+GB+GE=16.∴EA+GC+GE=16.∴GA+GE+GE+GE+EC=16.∴AC+2GE=16.∵GE=3,∴AC=10.28. 【答案】解:(1)C(2)==+=m-1+.29. 【答案】解:(2a3b2-3a2b+4a)·(-2b)=-4a3b3+6a2b2-8ab=-4(ab)3+6(ab)2-8ab=-4×33+6×32-8×3=-108+54-24=-78.30. 【答案】证明:如图,在AB 上截取AF =AD ,连接EF.∵AE 平分∠PAB ,∴∠DAE =∠FAE.在△DAE 和△FAE 中,⎩⎪⎨⎪⎧AD =AF ,∠DAE =∠FAE ,AE =AE ,∴△DAE ≌△FAE(SAS).∴∠AFE =∠ADE.∵AD ∥BC ,∴∠ADE +∠C =180°.又∵∠AFE +∠EFB =180°,∴∠EFB =∠C.∵BE 平分∠ABC ,∴∠EBF =∠EBC.在△BEF 和△BEC 中,⎩⎪⎨⎪⎧∠EFB =∠C ,∠EBF =∠EBC ,BE =BE ,∴△BEF ≌△BEC(AAS).∴BF =BC.∴AD +BC =AF +BF =AB.31. 【答案】(1)根据题意可得AD =t ,CD =6-t ,CE =2t. ∵△DEC 为等边三角形,∴CD =CE ,即6-t =2t ,解得t =2.∴当t 的值为2时,△DEC 为等边三角形.(2)∵∠A =90°,∠B =30°,∴∠C =60°. ①当∠DEC 为直角时,∠EDC =30°,∴CE =12CD ,即2t =12(6-t),解得t =65;②当∠EDC 为直角时,∠DEC =30°,∴CD =12CE ,即6-t =12·2t ,解得t =3.综上,当t 的值为65或3时,△DEC 为直角三角形.32. 【答案】【解析】由题意得2036703340x z x y y z --=⎧⎪--=⎨⎪+-=⎩,解方程组得3131x y z =⎧⎪⎪=⎨⎪⎪=⎩,代入所求代数式得313133143411313331333033n n n n n n n x y z x ---⎛⎫⎛⎫-=⋅⋅-=⋅⨯⋅-=-= ⎪ ⎪⎝⎭⎝⎭.。
人教版八年级下册物理期末复习《第8章运动和力》-填空题专练(有答案)-解析板
人教版八年级下册物理期末复习第8章运动和力填空题专练1.在探究“阻力对物体运动的影响”时,分别让同一小车从同一斜面的同一位置由静止下滑,在水平面上运动一段距离后停止。
在水平方向受到摩擦力,这个力对小车运动状态的影响是减小车的速度;小车三次在水平面上的运动,机械能的改变量相同(选填“相同”或“不同”)。
【考点】6N:阻力对物体运动影响的探究实验.【分析】(1)阻力改变小车的运动状态,使小车的运动速度减小;(2)影响动能的因素是质量和速度,影响重力势能的因素是质量和高度;动能和重力势能统称机械能;【解答】解:本实验是探究“阻力对物体运动的影响”,小车在水平方向受到摩擦力,这个力改变小车的运动状态,使小车的运动速度减小;同一小车三次在斜面上的高度相同,重力势能相同,在水平面上的运动时,最终停止运动,动能为零,则可知机械能的改变量相同。
故答案为:减小车的速度;相同。
【点评】本题考查了探究力与运动关系的实验,解题时要注意控制变量法的应用。
2.英国物理学家牛顿,总结了伽里略等人的研究成果,概括出了一条重要的规律,即牛顿第一定律:一切物体在没有受到力的作用时,总保持静止或匀速直线运动状态。
牛顿第一定律不是(填“是”或“不是”)直接通过实验验证得出来的,但经受住了无数的实践检验,因此牛顿第一定律已经成为公认的物理学基本定律之一。
【考点】6J:牛顿第一定律.【分析】根据牛顿第一定律的内容进行分析,即物体不受力时,可以一直做匀速直线运动,所以运动不需要力的维持。
力是改变物体运动状态的原因,运动的物体之所以停下来,是因为物体受到了与运动方向相反的力。
牛顿第一定律也叫惯性定律。
【解答】解:科学家伽利略通过实验分析得出:物体的运动并不需要力来维持,运动的物体之所以会停下来,是因为物体受到了与运动方向相反的力。
于是他推断:如果物体受到的力为零,物体将保持匀速直线运动;英国物理学家牛顿总结了伽利略等前人的研究成果,在实验的基础上,进一步推理、归纳、概括得出一条重要物理定律:一切物体在没有受到力的作用时,总保持静止或匀速直线运动状态。
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人教版八年级下期末专题复习综合填空一、阅读下面短文,在空白处按要求填入适当的单词或括号内单词的正确形式。
Most children like watching TV. It's very ___1___ (interest). By watching TV, they can see and learn a lot and know many things about ___2___ (they) country and the world. Of course, they can also learn over the radio. They can learn something more ___3___ (quick) from those TV ___4___ (program) because they can hear and watch at ___5___ same time. But they can't see anything over the radio. TV ___6___ (help) to open children's eyes and minds. Many children watch TV only on Saturday or Sunday evening, ___7___ they often have a lot of homework to do. But if they spend more time ___8___ (watch) TV, they will have ___9___ (little) time to do their lessons and fall ___10___ other students. So when you want to watch TV, you must remember, “Study must come first.”二、阅读下面短文,在空白处按要求填入适当的单词或括号内单词的正确形式。
Everyone needs to sleep. During the day you work and play; at night you sleep. Your body rests ___1___ you are sleeping. In the morning you are ready to work, study or play again. If you sleep ___2___ (good) at night, you can work or learn better in the day.Your body grows more while you are asleep. No one can live ___3___ sleeping. If a child is tired, he needs ___4___ (much) sleep than usual. You will be tired or will not be able to listen ___5___ your teachers in class or can't work well ___6___ you do not have enough sleep at night. A baby will cry loudly if you wake him or her up when he or she is sleeping. You will be able to work hard at ___7___ (you) lessons if you get enough rest. Many students hope to learn more before rests, so they study till late at night. But they feel very ___8___ (tire) in the day and they may forget more.It's very necessary for teenagers to get enough sleep. Boys and girls of eight or nine need ten ___9___ (hour) of sleep every night. So if you want to be strong and ___10___ (health), you should get enough sleep!三、阅读下面短文,在空白处按要求填入适当的单词或括号内单词的正确形式。
Where do you like to live? For this question, different people have different ___1___ (answer). Some people like to live in a city ___2___ there are many shops and supermarkets in it. They think it is convenient (方便的) to buy things. But some people think it is good to live in ___3___ quiet town because theydon't like the dirty air and ___4___ (noisy) in the big city. They ___5___ (like) the traffic and water pollution in the city, too.Today, some people like ___6___ (travel), so they would like to buy house cars. House car is both a house ___7___ a car. You can't buy it with a little money. There is a driving area in the car. You can do ___8___(lot) of things in the car. There is a bed and a lamp in the bedroom. You can make dinner in the kitchen. You can also find a fridge and a sink in it. You can listen ___9___ music and watch TV in the ___10___(sit) room. If you are tired, you can have a shower or a bath in the bathroom. You can do most things you want to do. Life is travelling. Do you want to live in this kind of car?四、阅读下面短文,在空白处按要求填入适当的单词或括号内单词的正确形式。
When you come to a new school, you may___1___ (feeling) a little lonely. Don't worry, you should not only study ___2___ (hard) than before, but also try to get new friends. How? You can pay attention ___3___ the people around you. Some of them may have the same interest as you, like music or movies. When you know a few of these people, you can try to join ___4___ (they) circles, so you'll meet more people who can be your friends. If you can be a good ___5___ (listen), you can win a lot of friendship. When your friends meet ___6___ (difficulty), they'll come to you. A friend in need is a friend indeed, a ___7___ (help) friend will always be welcome.Try to learn more knowledge in your spare time. It will make you ___8___ (confidence). A person who knows a lot will always be charming. Control your temper (脾气). Be patient ___9___ the people around you. Always remember "Don't treat ___10___ (other) the way you don't want to be treated (己所不欲,勿施于人)". If you can do all these things, I bet you will havea lot of good friends.五、阅读下面短文,在空白处按要求填入适当的单词或括号内单词的正确形式。
When people hear the word “stress (压力)”, they usually think of something bad. However, stress, can have several benefits (益处) for the body and mind. To begin with, people may feel stressed ___1___ there is something important to do. ___2___ example, some students are stressed before a big test. The stress might make them feel nervous but it ___3___ makes themfocused (注意力集中的). This type of stress can help people ___4___(work) efficiently (高效地) to meet their goals.Another way stress benefits us is by keeping us ___5___(health). Scientists who study stress learnt a little stress can make the immune (免疫的) system stronger, when your body learns to respond (反应) to some stress, it's able to protect you better from ___6___(ill).The final way that stress benefits us is by helping us respond to danger. If you see a car coming around the corner too fast, you might experience stress. This stress sends a message to warn your brain of danger, allowing your body to respond ___7___(quick). You may not be able to jump out of the car's way soon enough ___8___ the stress.Of course, too much stress is ___9___(harm) to our bodies and minds. But the right amount of stress makes us more efficient, healthier and ___10___(safe).参考答案:一、1.分析句子结构可知,此处需填形容词。