中考变式训练
中考必做的36道压轴题及变式训练
中考必做的36道压轴题及变式训练第一题夯实双基“步步高”,强化条件是“路标” 例1(北京,23,7分)在平面直角坐标系x O y 中,抛物线222--=mx mx y (0≠m )与y 轴交于点A ,其对称轴与x 轴交于点B .(1)求点A ,B 的坐标;(2)设直线l 与直线AB 关于该抛物线的对称轴对称,求直线l 的解析式;(3)若该抛物线在12-<<-x 这一段位于直线l 的上方,并且在32<<x 这一段位于直线AB 的下方,求该抛物线的解析式.(1)当 x = 0 时, y =-2 . ∴ A (0,-2). 抛物线对称轴为 x =212mm--=, ∴ B (1,0).(2)易得 A 点关于对称轴的对称点为 A (2,-2) 则直线 l 经过 A 、 B . 没直线的解析式为 y =kx +b 则22,0.k b k b +=-⎧⎨+=⎩解得2,2.k b =-⎧⎨=⎩∴直线的解析式为 y =-2x +2. (3)∵抛物线对称轴为 x =1抛物体在 2 <x <3 这一段与在-1<x <0 这一段关于对称轴对称,结合图象可以观察到抛物线在-2<x <1这一段位于直线 l 的上方,在 -1< x <0 这一段位于直线 l 的下方. ∴抛物线与直线 l 的交点横坐标为 -1 ; 当 x =-1 时, y =-2x (-1)+2 =4则抛物线过点(-1,4)当 x =-1 时, m +2m -2=4 , m =2 ∴抛物线解析为 y =2x 2 -4x -2 .连接(江苏南京,26,9分)已知二次函数y =a (x -m )2-a (x -m )(a 、m 为常数,且a ≠0).(1)求证:不论a 与m 为何值,该函数的图象与x 轴总有两个公共点; (2)设该函数的图象的顶点为C .与x 轴交于A 、B 两点,与y 轴交于点D . ①当△ABC 的面积等于1时,求a 的值;②当△ABC 的面积与△ABD 的面积相等时,求m 的值.【答案】(1)证明:y =a (x -m )2-a (x -m )=ax 2-(2am +a )x +am 2+am . 因为当a ≠0时,[-(2am +a )]2-4a (am 2+am )=a 2>0. 所以,方程ax 2-(2am +a )x +am 2+am =0有两个不相等的实数根. 所以,不论a 与m 为何值,该函数的图象与x 轴总有两个公共点. ………3分 (2)解:①y =a (x -m )2-a (x -m )=a (x -212+m )2-4a, 所以,点C 的坐标为(212+m ,-4a). 当y =0时,a (x -m )2-a (x -m )=0.解得x 1=m ,x 2=m +1.所以AB =1. 当△ABC 的面积等于1时,21×1×4a-=1. 所以21×1×(-4a )=1,或21×1×4a=1. 所以a =-8,或a =8.②当x =0时,y =am 2+am .所以点D 的坐标为(0,am 2+am ). 当△ABC 的面积与△ABD 的面积相等时,21×1×4a -=21×1×am am +221×1×(-4a )=21×1×(am 2+am ),或21×1×4a =21×1×(am 2+am ). 所以m =-21,或m =221--,或m =221+-.………9分 变式: (北京,23,7分)已知二次函数23(1)2(2)2y t x t x =++++在0x =和2x =时的函数值相等。
【中考英语总复习 真题探究与变式训练】专题07 动词(原卷版)
专题07 动词命题方向重要指数考向一动词辨析(必考点)考向二动词短语辨析(必考点)考向一动词辨析例1(2022·西藏·中考真题)(be动词辨析)The number of the students in our class ________ fifty-four.A.be B.is C.are D.am例2(2022·辽宁辽宁·中考真题)(感官动词辨析)The soup ________ a little salty, there is no need to add more salt.A.looks B.smells C.sounds D.tastes例3(2022·湖北黄石·中考真题)(同形动词辨析)—Don’t always________ yourself with others, or you may have much stress.—I can’t agree more.A.communicate B.connect C.consider D.compare例4(2022·湖北武汉·中考真题)(近义动词辨析)—Jack, tell me how to ________ this information.—All right, Grandma. You can type it on this keyboard.A.delete B.enter C.collect D.receive分类特点例句实义动词表示动作或状态,有完整的词义,能独立作谓语。
按其带不带宾语可分为Give me some ink, please. 请给我一些墨水。
及物动词和不及物动词。
He works hard. 他工作努力。
连系动词本身有词义,不能独立作谓语,必须和表语一起构成谓语,说明主语的状态、性质、特征或身份等。
He is a teacher. 他是一位老师。
【中考英语总复习 真题探究与变式训练】专题19 短文填空(解析版)
专题19 短文填空命题方向重要指数考向一自由填空(必考点)考向二选词填空(必考点)考向一自由填空例1(2022·宁夏·统考中考真题)(自由填空)阅读下面短文,在空白处填入适当的单词,单词的汉语提示或首字母已给出(每空一词)。
When I was a high school student, I wanted to go on a school trip. My parents said it was too expensive for them to pay for, so I decided to make money ____1____ (我自己). I got a part-time job in a bookstore. There were many people buying books there. I was ____2____ (忙碌的) all the time, and I got very tired, but I didn’t g____3____ up. I worked every F____4____ and Saturday night for a whole year. At the end of the year, I had enough money. I had a good t____5____ on the school trip, and my hard work at the bookstore made it possible. For me, it was a big achievement.【答案】1.myself 2.busy 3.(g)ive 4.(F)riday 5.(t)ime【导语】本文主要讲述了作者通过自己兼职赚得学校旅行需要的费用的故事。
1.句意:我的父母说这对他们来说太贵了,所以我决定自己赚钱。
myself“我自己”,反身代词,故填myself。
中考数学试题变式 变式训练
D3
C
O
x
D3 ( -
D2
等腰三角形的分类讨论
腰 一边
底
顶角 一角 底角 一腰上的高
形内 形外
一高
底边上的高
简解:过点A作AE⊥PB于E,过点C作CF⊥PB,交BP延 长线于F,由PB=5,S△PBC=5,得CF=2,由 PB=5,S△PAB=10, 得AE=4,易证 ∴BE=CF=2,∴S正ABCD=AB2=BE2+AE2=20
3、如图6,P是正方形ABCD外一点,PB=5, S△PAB=10,AM上是否存在点C,使 △ABC是等腰三角形
3 10 C1( 3 10 - 6,) - 6 - 3 10) ,- 3 10 C 2( 12 , 18 C 3( ) - 1 , 5) C 4(
变式二
平行四边形中点的存在性问题
如图,在平面直角坐标系中,函数y=2x+ 12的图象分别交x轴、y轴于A、B两点.过 点A的直线交y轴正半轴于点M,且点M为 线段OB的中点。
变式一
三角形中的点的存在性问题
如图,在平面直角坐标系中,函数y=2x+12的图象分别交x轴、y轴于A、 B两点.过点A的直线交y轴正半轴于点M,且点M为线段OB的中点。 在坐标轴上是否存在点C,使以A,B,C为顶点的三角形是等腰三角形?
如图,在平面直角坐标系中,函数y=2x+12的图 象分别交x轴、y轴于A、B两点.过点A的直线交y轴 正半轴于点M,且点M为线段OB的中点。
如图,在平面直角坐标系中,函数y=2x+12的图 象分别交x轴、y轴于A、B两点.过点A的直线交y 轴正半轴于点M,且点M为线段OB的中点。
在平面内是否存在点C,使以 A,B,M,C为顶点的四边形是等腰梯形?
【中考英语总复习 江苏专用 真题探究与变式训练】专题03 代词(解析版)
专题03 代词命题方向重要指数(必考点)考向一人称代词、物主代词和反身代词考向二指示代词和it的用法(常考点)考向三不定代词(重难点)考向一人称代词、物主代词和反身代词例1(2022·江苏连云港·中考真题)(人称代词做宾语)Our English teacher, Miss Li, is kind and patient. We all like ________.A.she B.her C.hers D.herself【答案】B【详解】句意:我们的英语老师,李老师,善良又耐心。
我们都喜欢她。
考查代词辨析。
she她,人称代词主格;her她,人称代词宾格;hers她的,名词性物主代词;herself她自己,反身代词。
此空位于动词like后,表示喜欢她,应填人称代词宾格,故选B。
例2(2020·江苏宿迁·中考真题)(人称代词做主语)—Where are Lily and Lucy from?—____ are from the USA.A.Ours B.We C.Theirs D.They【答案】D【详解】句意:——莉莉和露西来自哪里?——他们来自美国。
考查人称代词主格。
Ours我们的,名词性物主代词;We我们,人称代词主格;Theirs他们的,名词性物主代词;They他们,人称代词主格。
根据题干,可知空缺处是主语,用主格代词,主语Lily和Lucy两个人表第三人称复数。
故选D。
例3(江苏省南京市2021年中考英语试题)(形容词性物主代词修饰名词)Amy hid under ________ desk in a hurry when the earthquake happened.A.she B.her C.hers D.herself【答案】B【详解】句意:地震发生时,艾米匆忙地躲在她的桌子下面。
考查代词辨析。
she她,主格;her她,宾格/她的,形容词性物主代词;hers她的,名词性物主代词;herself反身代词。
【中考英语总复习 江苏专用 真题探究与变式训练】专题01 冠词(原卷版)
专题01 冠词命题方向重要指数考向一定冠词(必考点)考向二不定冠词(必考点)考向三零冠词考向一定冠词例1(2022·江苏淮安·中考真题)(定冠词用在最高级)Autumn is ________ best season to visit the Great Wall in China.A./ B.a C.an D.the例2(2022·江苏镇江·中考真题)(定冠词用于特指)The 2022 Winter Olympics impressed me a lot, and _______ moment Xu Mengtao won the gold medal moved me the most.A.a B.an C.the D.不填例3(2022·江苏扬州·中考真题)(定冠词用于固定搭配和专用名词)China has helped end 70% of poverty worldwide since ________ late 1970s, according to ________ World Bank.A.a; a B.the; the C.a; the D.the; a例4(2020·江苏淮安·中考真题)(定冠词用于乐器前)—Amy, do you know Langlang and his wife?—Of course. They play _________ piano well.A.a B.an C./ D.the例5(2020·江苏镇江·中考真题)(定冠词用于序数词)Peng Min finally became the winner of___________ season of CCTV's Chinese Poetry Conference.A.five B.fifth C.the fifth D.fifths定冠词用法详解:1. 定冠词the用来特指双方都清楚的人、事、物。
中考专题——变式训练及答案
中考专题——变式训练及答案1.如图所示,四边形ABCD 是正方形,E 点在边DE 上,F 点在线段CB •的延长线上,且∠EAF=90°. (1)试证明:△ADE ≌△ABF .(2)△ADE 可以通过平移、翻转、旋转中的哪种方法到△ABF 的位置.(3)指出线段AE 与AF 之间的关系.2.(1)如图a ,点O 是线段AD 的中点,分别以AO 和DO 为边在线段AD 的同侧作等边三角形OAB 和等边三角形OCD ,连结AC 和BD ,相交于点E ,连结BC .(1)求∠AEB 的大小; (2)如图b ,ΔO AB 固定不动,保持ΔOCD 的形状和大小不变,将ΔOCD 绕着点O 旋转(ΔOAB 和ΔOCD 不能重叠),求∠AEB 的大小. 3.(1)如图10,在Rt △ABC 中,AC =BC ,∠ACB =90°,M 为AB 中点,AF=CE ,请判断△MEF 的形状.(2)已知:如图11在Rt △ABC 中, AC=BC, ∠C=90°,点D 为AB 上任一点,DF ⊥AC 于F , DE ⊥BC 于E ,M 为BC 的中点.① 判断△MEF 是什么形状的三角形并证明你的结论.② 当点D 在AB 上运动时,四边形FMEC 的面积是否会改变,并证明你的结论. ③ 当点D 在BA 的延长线上运动时,如图12,①中的结论还成立吗?4.已知:正方形中,,绕点顺时针旋转,它的两边分别交(或它们的延长线)于点.当绕点旋转到时(如图18),易证.(1)当绕点旋转到时(如图19),线段和之间有怎样的数量关系?写出猜想,并加以证明. (2)当绕点旋转到如图20的位置时,线段和之间又有怎样的数量关系?请直接写出你的猜想.C BOD 图a A B O D CE 图b图3D5.(1)如图1,已知矩形ABCD 中,点E 是BC 上的一动点,过点E 作EF ⊥BD 于点F ,EG ⊥AC 于点G ,CH ⊥BD 于点H ,试证明CH=EF+EG;(2) 若点E 在BC的延长线上,如图2,过点E 作EF ⊥BD 于点F ,EG ⊥AC 的延长线于点G ,CH ⊥BD 于点H , 则EF 、EG 、CH 三者之间具有怎样的数量关系,直接写出你的猜想;(3) 如图3,BD 是正方形ABCD 的对角线,L 在BD 上,且BL=BC, 连结CL ,点E 是CL 上任一点, EF ⊥BD 于点F ,EG ⊥BC 于点G ,猜想EF 、EG 、BD 之间具有怎样的数量关系,直接写出你的猜想;(4) 观察图1、图2、图3的特性,请你根据这一特性构造一个图形, 使它仍然具有EF 、EG 、CH 这样的线段,并满足(1)或(2)的结论,写出相关题设的条件和结论. 6. 在四边形ABCD 中,对角线AC 平分∠DAB . (1)如图①,当∠DAB =120°,∠B =∠D =90°时, 求证:AB +AD =AC .(2)如图②,当∠DAB =120°,∠B 与∠D 互补时, 线段AB 、AD 、AC 有怎样的数量关系? 写出你的猜想,并给予证明. (3)如图③,当∠DAB =90°,∠B 与∠D 互补时, 线段AB 、AD 、AC 有怎样的数量关系? 写出你的猜想,并给予证明.7. 在ABC △中,AC=BC ,90ACB ∠=︒,点D 为AC 的中点.(1)如图1,E 为线段DC 上任意一点,将线段DE 绕点D 逆时针旋转90°得到线段DF ,连结CF ,过点F 作FH FC ⊥,交直线AB 于点H .判断FH 与FC 的数量关系并加以证明. (2)如图2,若E 为线段DC 的延长线上任意一点,(1)中的其他条件不变,你在(1)中得出的结论是否发生改变,直接写出你的结论,不必证明.FHFED ADA 图1D8. 如图1,BD 、CE 分别是△ABC 的外角平分线,过点A 作AF ⊥BD ,AG ⊥CE ,垂足分别为F 、G ,连接FG ,延长AF 、AG ,与直线BC 相交于M 、N . (1)试说明:FG= 12(AB+BC+AC );(2)如图2,若BD 、CE 分别是△ABC 的内角平分线,则线段FG 与△ABC 三边又有怎样的数量关系?请写出你的猜想,并对其中的一种情况说明理由;(3)如图3,若BD 为△ABC 的内角平分线,CE 为△ABC 的外角平分线,则线段FG 与△ABC 三边的数量关系是9. 两块等腰直角三角板△ABC 和△DEC 如图摆放,其中∠ACB =∠DCE = 90°,F 是DE 的中点,H 是AE 的中点,G 是BD 的中点. (1)如图1,若点D 、E 分别在AC 、BC 的延长线上,通过观察和测量,猜想FH 和FG 的数量关系为_______和位置关系为______;(2)如图2,若将三角板△DEC 绕着点C 顺时针旋转至ACE 在一条直线上时,其余条件均不变,则(1)中的猜想是否还成立,若成立,请证明,不成立请说明理由;(2)如图3,将图1中的△DEC 绕点C 顺时针旋转一个锐角,得到图3,(1)中的猜想还成立吗?直接写出结论,不用证明.图3图1图2AD E C HF G变式训练答案1.解:(1)90909090EAF BAF BAEBAD DAE BAE∠=︒⇒∠+∠=︒⎫⇒⎬∠=︒⇒∠+∠=︒⎭∠EAF=∠EAD,而AD=AB,∠D=∠ABF=90°,故△ADE≌△ABF.(2)可以通过旋转,将△ADE绕点A顺时针旋转90°就可以到△ABF的位置.(3)由△ADE≌△ABF可知AE=AF.2.解析:(1)∵在等边三角形OAB和等边三角形OCD中,OC=OD,OA=OB,∠AOB=∠COD=60°,∴∠AOB+∠BOC=∠COD+∠BOC,即∠AOC=∠BOD.∵在△AOC和△BOD中∴△AOC≌△BOD(SAS)∴∠OAC=∠OBD∵∠1=∠OAC+∠AOB=∠OBD+∠AEB∴∠AEB=∠AOB=60°.(2)同(1)可证∠AEB=∠AOB=60°.3.思路点拨:在等腰三角形中,M为底边AB的中点,连结CM是常用的辅助线.解析:(1)△MEF是等腰直角三角形.(2)①△MEF是等腰直角三角形.理由如下:连结CM,如图13∵DF⊥AC于F,DE⊥BC于E,∠ACB=90°∴四边形CEDF为长方形,∴DF=CE∵在Rt△ABC中,AB=AC,∠ACB=90°,M为AB中点,∴∠A=∠1=45°,CM⊥AB,AM=BM=CM.∵在Rt△ADF中,∠A=45°∴AF=DF,∴AF=CE∵在△AMF和△CME中∴△AMF≌△CME(SAS)∴MF=ME,∠2=∠3∵∠2+∠CMF=90°,∴∠3+∠CMF=90°,即∠EMF=90°∴△MEF是等腰直角三角形.②当点D在AB上运动时,四边形FMEC的面积不会改变,证明如下:由①可知,△AMF≌△CME,∴S△AMF=S△CME.∵S△ACM=S△BCM,∴S△CMF=S△BME,∴S四边形FMEC=S△CMF+ S△CME=S△ABC.∴四边形FMEC的面积不会改变.③成立,理由如下:连结CM,如图14∵DF⊥AC于F,DE⊥BC于E,∠ACB=90°∴四边形CEDF为长方形,∴DF=CE∵在Rt△ABC中,AC=BC,∠ACB=90°,M为AB中点,∴∠BAC=∠1=45°,CM⊥AB,AM=BM=CM.∴∠MAF=∠MCE=135°.∵在Rt△ADF中,∠DAF=∠BAC=45°∴AF=DF,∴AF=CE∵在△AMF和△CME中∴△AMF≌△CME(SAS)∴MF=ME,∠AMF=∠CME∵∠CME+∠AME=90°,∴∠AMF+∠AME=90°,即∠EMF=90°∴△MEF是等腰直角三角形.5.分析:(1)要证明CH=EF+EG首先要想到能否把线段CH分成两条线段而加以证明,就自然的想到添加辅助线,若作CE⊥NH于N,可得矩形EFHN,很明显只需证明EG=CN,最后根据AAS可求证△EGC ≌△CNE得出结论.(2)过C点作CO⊥EF于O,可得矩形HCOF,因为HC=DO,所以只需证明EO=EG,最后根据AAS可求证△COE≌△CGE得出猜想.(3)连接AC,过E作EG作EH⊥AC于H,交BD于O,可得矩形FOHE,很明显只需证明EG=CH,最后根据AAS可求证△CHE≌△EGC得出猜想.(4)点P是等腰三角形底边所在直线上的任意一点,点P到两腰的距离的和(或差)等于这个等腰三角形腰上的高,很显然过C作CE⊥PF于E,可得矩形GCEF,而且AAS可求证△CEP≌△CNP,故CG=PF-PN.解答:(1)证明:过E点作CN⊥CH于N(1分)∵EF⊥BD,CH⊥BD,∴四边形EFHN是矩形.∴EF=NH,FH∥EN.∴∠DBC=∠NEC.∵四边形ABCD是矩形,∴AC=BD,且互相平分∴∠DBC=∠ACB∴∠NEC=∠ACB∵EG⊥AC,EN⊥CH,∴∠EGC=∠CNE=90°,又EC=EC,∴△EGC≌△CNE.(3分)∴EG=CN∴CH=CN+NH=EG+EF(4分)(2)解:猜想CH=EF-EG(5分)(3)解:EF+EG= 12BD(6分)(4)解:点P是等腰三角形底边所在直线上的任意一点,点P到两腰的距离的和(或差)等于这个等腰三角形腰上的高.如图①,有CG=PF-PN.6. (1)由AC平分∠DAB,∠DAB=120°,可得∠CAB=∠CAD=60°,又由∠B=∠D=90°,即可得∠ACB=∠ACD=30°,根据直角三角形中30°角所对的直角边等于斜边的一半,即可得AB+AD=AC;(2)首先过C点分别作AD和AB延长线的垂线段,垂足分别为E、F,由AC平分∠DAB,可得CE=CF,又由∠B与∠D互补,可证得△CED≌△CFB,则可得AD+AB=AE+AF,又由AE+AF=AC,则可得线段AB、AD、AC有怎样的数量关系为AB+AD=AC;(3)首先过C点分别作AB和AD延长线的垂线段,垂足分别是E、F,与(2)同理可得△CEB≌△CFD,则可得∠G=∠DAC=∠CAB=45°,即可求得线段AB、AD、AC有怎样的数量关系为AB+AD= 2AC.解答:证明:(1)在四边形ABCD中,∵AC平分∠DAB,∠DAB=120°,∴∠CAB=∠CAD=60°.又∵∠B=∠D=90°,∴∠ACB=∠ACD=30°.∴AB=AD= 12AC,即AB+AD=AC.(2)AB+AD=AC.证明如下:如图①,过C点分别作AD和AB延长线的垂线段,垂足分别为E、F.∵AC平分∠DAB,∴CE=CF.∵∠ABC+∠D=180°,∠ABC+∠CBF=180°,∴∠CBF=∠D.又∵∠CED=∠CFB=90°,∴△CED≌△CFB.∴ED=BF.∴AD+AB=AE+ED+AB=AE+BF+AB=AE+AF.由(1)知AE+AF=AC.∴AB+AD=AC.(3)AB+AD= 2AC.证明如下:如图②,过C点分别作AB和AD延长线的垂线段,垂足分别是E、F.∵AC平分∠DAB,∴CE=CF.∵∠ABC+∠ADC=180°,∠ADC+∠FDC=180°,∴∠ABC=∠FDC.又∵∠CEB=∠CFD=90°.∴△CEB≌△CFD.∴CB=CD.延长AB至G,使BG=AD,连接CG.∵∠ABC+∠ADC=180°,∠ABC+∠CBG=180°,∴∠CBG=∠ADC.∴△GBC≌△ADC.∴∠G=∠DAC=∠CAB=45°.∴∠ACG=90°.∴AG= 2AC.∴AB+AD= 2AC.7. 1)证明;在BC上截取BF=AD,连接DF.则三角形DCF为等边三角形,DF=DC.又BF=EG,AD=CE=BF.则FG=CG.所以,DG⊥CG.(等腰三角形底边的中线也是底边上的高)2)(1)的结论还成立.证明:在BC的延长线上截取线段CF=CD.又∠DCF=∠ACB=60°,则三角形CDF为等边三角形,得CD=FD;AD=CE,即AC+CD=CF+EF,BC+CF=CF+EF,得BC=EF;又点G为BE的中点,即:BG=EG.则BG-BC=EG-EF,得CG=FG.故DG⊥BC.(等腰三角形"三线合一")8.分析:(1)由AF⊥BD,∠ABF=∠MBF,得到∠BAF=∠BMF,进一步推出MB=AB,AF=MF,同理CN=AC,AG=NG,即可得出答案;(2)延长AF、AG,与直线BC相交于M、N,与(1)类似可以证出答案;(3)与(1)方法类同即可证出答案.解答:解:(1)∵AF⊥BD,∠ABF=∠MBF,∴∠BAF=∠BMF,∴MB=AB∴AF=MF,同理:CN=AC,AG=NG,∴FG是△AMN的中位线∴FG= 12MN,= 12(MB+BC+CN),= 12(AB+BC+AC).(2)图(2)中,FG= 12(AB+AC-BC)解:如图(2),延长AF、AG,与直线BC相交于M、N,由(1)中可知,MB=AB,AF=MF,CN=AC,AG=NG∴FG= 12MN,= 12(BM+CN-BC),= 12(AB+AC-BC),答:线段FG与△ABC三边的数量关系是FG= 12(AB+AC-BC).(3)解:FG= 12(AC+BC-AB),理由是:延长AF、AG,与直线BC相交于M、N,同样由(1)中可知,MB=AB,AF=MF,CN=AC,AG=NG∴FG= 12MN,= 12(CN+BC-BM),= 12(AC+BC-AB).故答案为:FG= 12(AC+BC-AB).9.(1)解:∵DE=CD,AC=BC,∠ECA=∠DCB=90°,∴BE=AD,∵F是DE的中点,H是AE的中点,G是BD的中点,∴FH= 12AD,FH∥AD,FG= 12BE,FG∥BE,∴FH=FG,∵AD⊥BE,∴FH⊥FG,故答案为:相等,垂直.(2)答:成立,证明:∵CE=CD,∠ECD=∠ACD=90°,AC=BC,∴△ACD≌△BCE∴AD=BE,由(1)知:FH= 12AD,FH∥AD,FG= 12BE,FG∥BE,∴FH=FG,FH⊥FG,∴(1)中的猜想还成立.(3)答:成立,结论是FH=FG,FH⊥FG.。
【中考英语总复习 江苏专用 真题探究与变式训练】专题09 非谓语动词(原卷及答案)
专题09 非谓语动词命题方向重要指数考向一动词不定式(必考点)考向二动名词(常考点)考向一动词不定式例1(2022·江苏盐城·中考真题)(动词不定式作目的状语)Good news comes that China has sent Shenzhou XIV to space ________ the unknown world.A.explore B.explored C.exploring D.to explore例2(2022·江苏镇江·中考真题)(动词不定式作宾补)The high school invited a famous scientist _______ a talk on World Earth Day.A.giving B.to give C.give D.given例3(2022·江苏连云港·中考真题)(不定式的常见句型too adj/adv+to do sth)Kitty, these books are ________ heavy for you ________ carry. Let me help you.A.as…as B.too…to C.such…that D.so…that例4(2022·江苏连云港·中考真题)(疑问词+to do作宾语)We learned ________ to work as a team by completing the task.A.what B.which C.how D.who例5(2021·江苏南通·中考真题)(不定式的常见句型adj. enough to do)The community worker is patient enough ________ to the old how to use Health Code(码).A.explain B.explains C.to explain D.explaining动词不定式在中考语法项目中,主要考查动词不定式作宾语、宾语补足语、目的状语。
中考语文专题复习及变式训练专题:病句修改
中考专题复习——病句修改一、复习目标:1.辨析病句类型。
2.辨析并修改病句。
二、病句类型(要求:请用正确的修改符号在原句中修改。
)1.搭配不当(1)主谓搭配不当例:他那崇高的革命品质,经常浮现在我的脑海中。
(2)动宾搭配不当例:课文里乘船看戏的插图,却给我发生了极为深刻的印象。
(3)主宾搭配不当例:这最后一天的劳动是同学们最紧张、最愉快、最有意义的一天。
(4)修饰语(定语、状语、补语)和中心语搭配不当例:这次研讨会上,大家对小组评价问题交换了广泛的意见。
(5)关联词搭配不当例:我们中学生如果缺乏创新精神,也不能适应社会发展的要求。
(6)一面与两面搭配不当例:成绩的提高,取决于我们自身是否努力。
(7)否定与肯定搭配不当例:大家并不否认他的观点没有可取之处。
2.成分残缺或赘余(1)成分残缺①缺主语:例:A:通过专家的这次讲座,对我们的启发很大。
例:B:鉴于当前甲型H1N1流感疫情仍在一些国家和地区蔓延,我国也发现多例输入性确诊病例,必须引起我们高度重视,全力控制疫情在我国传播。
例:C:《红楼梦》当然是旷世杰作,但由于曹雪芹所处的朝代和出身的局限,不能不在他的作品中有所反映。
②缺谓语:例:很多同学衣来伸手、饭来张口的生活,这对培养自理能力是很不利的。
③缺宾语:例:张明荣获潍坊市三好学生。
④缺介词或必要的限制语例:A:刚才,王爽同他关系最铁的朋友吵起来了。
例:B:细菌是有害的微生物。
(2)重复多余句子结构完整,句意清晰,却使用了不必要的词或短语,造成句子的成分赘余。
常见的情况有:主谓宾多余、修饰成分或附加成分多余。
①主语赘余例:我们组的同学,在上课的时候,一般地说,我们都能认真听讲,遵守课堂纪律。
②谓语赘余例:他们选出了自己信任的班长,负责掌握管理全班的琐碎事务。
④宾语赘余例:他不知不觉走了十里路左右的路程。
⑤修饰成分、附加成分多余例:A:据刚刚最新收到的消息,我国女子乒乓球队再次获得世乒赛团体冠军。
例:B:张老师做什么事情都非常认真得很。
备考2023年中考数学变式阶梯训练17--20题附解析教师版
备考2023年中考数学变式阶梯训练17--20题附解析教师版一、第十七题(共7题;共75分)1.(10分)计算:(-6) ×( 23-■)-23. 圆圆在做作业时,发现题中有一个数字被墨水污染了。
(1)(5分)如果被污染的数字是 12 .请计算(-6)×( 23 - 12 )-23.(2)(5分)如果计算结果等于6,求被污染的数字.【答案】(1)解:(-6)×( 23 - 12)-23=(-6)× 16 -8=-1-8 =-9(2)解:设被污染的数字为x , 由题意,得(-6)×( 23 -x)-23=6解得x=3,∴被污染的数字是3.【解析】【分析】(1)将被污染的数字代入,先算乘方和括号里的减法运算,再算乘法运算,然后利用有理数的减法法则进行计算.(2)设被污染的数字为x ,根据计算结果等于6,可得到关于x 的方程,解方程求出x 的值.2.(10分)嘉淇在解一道数学计算题时,发现有一个数被污染了.(1)(5分)嘉淇猜污染的数为1,请计算(−1)3×1−(1−3)÷4;(2)(5分)老师说,嘉淇猜错了,正确的计算结果不小于52,求被污染的数最大是几?【答案】(1)解:(−1)3×1−(1−3)÷4=−1+12=−12(2)解:设污染了的实数为x ,则有−x +12≥52解之得,x ≤−2所以被污染的实数最大是-2.【解析】【分析】(1)先计算乘方,再计算乘除,最后计算减法即可;(2)设污染了的实数为x ,根据题意列出不等式−x +12≥52求解即可。
3.(10分)某同学在解关于y 的方程3y−a 4−5y−7a 6=1去分母时、忘记将方程右边的1乘以12,从而求得方程的解为y =10. (1)(5分)求a 的值; (2)(5分)求方程正确的解.【答案】(1)解:该同学去分母时方程右边的1忘记乘12,则原方程变为3(3y −a)−2(5y −7a)=1, 此时方程的解为y =10,代入得3(30−a)−2(50−7a)=1 整理得:11a =11, 解得a =1(2)解:将a =1代入方程3y−a 4−5y−7a 6=1,得3y−14−5y−76=1去分母:3(3y −1)−2(5y −7)=12 去括号:9y −3−10y +14=12 整理得:−y =1 解得y =−1即原方程的解为y =−1【解析】【分析】(1)先求出 3(3y −a)−2(5y −7a)=1, 再求出 y =10, 最后求解即可;(2)先求出 3y−a 4−5y−7a 6=1, 再求出3y−14−5y−76=1 ,最后解方程即可。
【真题探究与变式训练】专题12中国的自然环境(原卷版)
主题三中国地理专题12 中国的自然环境中考命题方向考向一地形和地势考向二气候考向三河流考向四自然灾害考向一地形和地势例1(2022·辽宁葫芦岛)读中国各类地形面积比例图,完成下面1-2小题。
1.我国各类地形中,面积所占比例最大的是()A.丘陵B.山地C.平原D.高原2.我国地形的类型特征是()①类型多样②山区面积广大③类型单一④耕地面积广大A.①②B.②③C.①④D.③④例2(2022·黑龙江哈尔滨)读中央气象台2022年五一假期天气提示图,完成下面3-4小题。
3.据图可知,提示注意保暖的地区是()A.东南丘陵B.华北平原C.青藏高原D.四川盆地4.图中气温适宜的省区是()A.云南省B.黑龙江省C.广东省D.陕西省例3(2022·海南·中考真题)我国地域辽阔,自然环境复杂多样。
读图“中国地势三级阶梯分布示意图(北纬36°剖面)”,完成下面5-6小题。
5.我国地势的总体特征是()A.东高西低,呈斜坡状分布B.南高北低,呈阶梯状分布C.北高南低,呈斜坡状分布D.西高东低,呈阶梯状分布6.位于地势第一级阶梯的地形区是()A.青藏高原B.黄土高原C.华北平原D.四川盆地例4(2022·新疆·中考真题)山脉是地形的骨架。
据下图完成下面7-8小题。
7.图中所在的地形区描述正确的是()A.①为黄土高原B.②为华北平原C.③为青藏高原D.④为柴达木盆地8.图中位于我国地势第一级阶梯的地形区是()A.①B.②C.③D.④例5(2022·北京·中考真题)山脉是地形的骨架、通行的阻碍、河流的源头、风沙的屏障……图左为太行山脉及周边地区简图,图右为军都陉沿线地区等高线地形图。
读图,回答下列问题。
(1)太行山脉是我国重要的地理界线之一,将其两侧的地形区和地势阶梯填在①—④处。
①____②____③____④____陉(xíng),是指狭窄的通道。
专题14阅读理解之记叙文中考英语总复习真题探究与变式训练(江苏专用)(原卷版)
专题14 阅读理解之记叙文例1(2022·江苏淮安·统考中考真题)Once a rich businessman gave his daughter a beautiful necklace. But later the necklace for the girl went missing. The businessman offered a reward of $50,000 for anyone who could find it.One day Robin was walking home along a dirty river. He saw something shining in the river. It was the diamond necklace! He decided to catch it so that he could get the reward.He put his hand in the dirty river and tried to catch the necklace, but somehow missed it.He tried again. This time he walked into the river and put his whole arm in to catch the necklace. But strangely, he still missed it!He came out and started walking away. Then again he saw the necklace, right there. He decided to give it a final try.He jumped into the dirty water and searched everywhere for the necklace but still he failed. He came out feeling very sad.Just then an old man, who was walking by, saw him and asked what was wrong. At first Robin did not want to share the secret with the old man. But finally he decided to tell the truth.He told the old man about the necklace and how he tried to catch it. The old man then said, “Perhaps you should try looking up, towards the branches(枝条)of the tree, instead of in the dirty river.Robin looked up and the necklace was indeed on a branch of the tree. He had tried to catch a reflection(倒影)of the real necklace all the time.1.Robin decided to catch the necklace in the river to _________.A.sell it for money B.get the rewardC.help the businessman D.marry the girl2.How many times did Robin try to catch the necklace from the river?A.Two. B.Three. C.Four. D.Five.3.From the story, we know the old man was __________.A.wise B.foolish C.strict D.modest4.The story wants to tell us that _________.A.we shouldn’t waste time catching the necklaceB.we’d better help each other when in troubleC.we need to change the way of thinking sometimesD.we should take and follow old people’s advice例2(2022·江苏盐城·统考中考真题)Maggie, Travis and Lucy’s science teacher set a special test for them. They had to work out different kinds of problems within limited time to get out of a locked room.For the past hour, Maggie, Travis and Lucy had been locked inside a room decorated like a mad scientist’s laboratory. Together they decoded(破译)a secret language and solved a difficult maths problem.The last challenge, however, stopped them. The key to the door was trapped in a block of ice.“We have to melt the ice,” Lucy said.“But there’s nothing hot here!” Maggie complained.Travis pulled off his sweatshirt and wrapped(裏)it around the ice. “This keeps me warm,” he reasoned.A few minutes passed by, but the ice didn’t melt.“Isn’t cloth an insulator(隔热材料)?” Lucy asked. She tried to remember what she had learned in science c lass. “Heat always flows from warm objects to cold ones. The heat in the air will eventually melt the ice, but we need to find something that will help heat move from the air to the ice more quickly.”“What about glass?” Maggie asked.“Glass is also an insulator. It keeps heat from moving,” Lucy said. Then she noticed a large metal tray(金属托盘)across the room. “This might work!”Lucy put the block of ice onto the tray. Everybody’s eyes moved between the clock and the ice. Would they be able to free the key in time?At last, the key lay in the water on the tray. The three friends rushed out of the room in the last minute.“We made it!” Travis cheered. “Good thing you paid attention in science class!”5.What final challenge did the three friends need to complete?A.To solve a maths problem. B.To learn a secret language.C.To find their science teacher. D.To get the key trapped in ice.6.What does Travis mean by saying “This keeps me warm”?A.His sweatshirt can help melt the ice. B.He dislikes his sweatshirt.C.His sweatshirt is of good quality. D.He wants to take off his sweatshirt.7.What does the underlined word “eventually” probably mean?A.carefully B.suddenly C.finally D.properly8.What’s the best title for the story?A.Changing Ice into Water B.Decorating the LaboratoryC.Running away from the Room D.Preparing for a Science Class例3(2022·江苏常州·统考中考真题)The Beijing 2022 Olympics was the most gender-balanced (性别平衡的) Winter Olympic Games in history, with more than 1,300 female athletes — a record number — competing at the events, making up more than 45 percent of all athletes. Here are some female athletes whose achievements in Beijing amazed the world.Team China’s teenage hero Gu Ailing, 18, is the youngest athlete to win three medals at a Winter Olympics. The freeski player won two gold medals and a silver in three events.Russia’s skating silver medalist Alexandra Trusova, 17, amazed the world with five quadruple jumps (四周跳) during free skate at the Beijing Winter Olympics. No other woman has ever finished five quadruple jumps in an Olympic competition.British women’s curling (冰壶) team won the country’s only gold medal by having a 10-3 win against Japan on the last day of the Beijing Winter Olympics. This was also the country’s first curling gold after 2002.Almida de Val, a 24-year-old Swedish IT engineer, together with her teammate, took the third place in curling mixed doubles. She took a leave from her company to take part in the Olympics.9.How many athletes took part in the Beijing 2022 Olympic Games?A.Around 1,300. B.Around 1,580. C.Around 2,880. D.Around 4,460.10.Who took a silver medal in the competition?A.Gu Ailing. B.British women’s curling team.C.Almida de Val. D.Almida de Val’s teammate.11.What do we know about Alexandra Trusova?A.She is the youngest athlete in the 2022 Olympic Games.B.She took the first place in the Beijing Winter Olympics.C.She worked as an IT engineer before becoming a skating player.D.She is the first female to complete five quadruple jumps in an Olympic competition.(2022·江苏镇江·统考中考真题)When everyone was ready, Peter knocked on the door gently.The door opened slowly, and a lady came out. It was Wendy. The boys all took off their hats “Where am I?” Wendy asked.Of course, Slightly was the first to get a word in.“Wendy lady,’’ he said quickly, “we built this house for you.’’“Oh, please say you like it!” cried Nibs.“What a lovely, lovely house,” Wendy said. The boys were delighted. “We are your children.” said the twins.They all lowered their knees and held out their arms.“Oh, Wendy lady, please be our mother!” they cried in union.“I would love to,” said Wendy, “but you see I am only a little girl. I have no experience of being a mother.”“_______” said Peter. “We just need a nice motherly person.”“Oh, really?” Wendy said. “I think that is exactly what I am.’’“It is. It is!” they all cried.“Very well,” she said, “I will do my best. Come inside now you naughty children. I think there’s just enough time for me to finish the story of Cinderella before I put you to bed.”They went in, and that was the first of the many joyful evenings they had with Wendy. By and by she made them comfortable in the big bed in their home under the trees. But she herself slept that night in the little house. Peter kept watching outside with a sword(剑), because the pirates(海盗) could be heard drinking far away, and the wolves were going about for food. The little house looked very warm and safe in the darkness. After some time,Peter fell asleep, and all was still and quiet in the Neverland.(adapted from Peter Pan)12.Which of the following is the most suitable for the blank(空格)?A.It’s really a pity.B.It’s my pleasure.C.That doesn’t matter.D.I’m sorry to hear that.13.According to this passage, Peter is __________.A.polite and brave B.curious and creativeC.patient and practical D.modest and confident14.What can we learn from the passage?A.There was possible danger around the house.B.The children disliked the story told by Wendy.C.Peter fell asleep after he drove the pirates away.D.Wendy was unwilling to be the children’s mother.(2022·江苏常州·统考中考真题)This is a typical(典型的) day for Yang Jinlong.At 9 a. m. , he drives to primary schools and middle schools in Xi’an, Shaanxi Province, to teach students about Shaanxi kuaiban. It is a traditional Chinese form of storytelling to the rhythm(节奏) of bamboo clappers(响板), which the art form is named after. Sometimes, he helps students prepare for competitions. Usually, his classes run until about 6. p.m. , and then he returns home to prepare classes for the next day.On June 10, the Ministry of Culture and Tourism announced 325 national intangible cultural heritage(非物质文化遗产) items in Beijing, increasing the list to 1, 557 items. Shaanxi kuaiban, which appeared during the late Qing Dynasty, has been included. The art form has been introduced to local schools as part of their art education.Yang has been teaching young people the art form since 2003 after graduating from the National Academy of Chinese Theatre Arts in Beijing. He studied quyi there. Quyi is general term for Chinese folk art forms, including storytelling, crosstalk and clapper talk.“Art education is important for students in China. Just as many students learn to play Western musical instruments like the piano and violin, there are many people learning traditional Chinese folk arts, including Shaanxi kuaiban, which I’ll work for my whole life,” he said.Kuaiban is popular in northern China, including Beijing and Tianjin. According to Yang, Shaanxi kuaiban was influenced by the art of different areas. The art form can be played by a group of players or only one. With one or two pairs of kuaiban of different sizes in hand, the players speak in the local dialect(方言) while telling stories,which are usually about heroes. The playe r tells stories while playing kuaiban, and it’s easy for the watchers to remember the stories since all the lines rhym.Thanks to artists like Yang, this traditional Chinese form of storytelling is passed on and stays alive in our country.15.Why is today a typical day for Yang Jinlong?A.He is teaching students about kuaiban as usual.B.His work starts at 9 and lasts 6 hours like every day.C.He is preparing for a kuaiban competition today.D.His life today is as busy and boring as every day.16.Which of the following about Shaanxi kuaiban is TRUE?A.It is named after the Shaanxi dialect.B.It is listed in the national intangible cultural heritage.C.It is more popular than the piano and violin in northern China.D.It is played to tell stories usually about common people.17.Which of the following best describes Yang Jinlong?A.Devoted. B.Stressed. C.Generous. D.Curious.18.Why does the writer report Yang Jinlong’s story?A.To show how to play Shaanxi kuaiban in the local dialect.B.To tell the difference between Chinese and Western arts.C.To prove that kuaiban players are living a busy life.D.To praise the work of spreading traditional Chinese art.2022·江苏徐州·统考中考真题)Peter loves baseball. Last summer, he helped coach a school baseball team. When he first watched the team of 12-year-olds play baseball, his first impressions were not really positive.One player often left as soon as they started losing. Another player paid too much attention to all their mistakes during the game. Other boys preferred to dig up the grass when they weren’t in the play. A lot of boys threw their baseball bats when they lost the catch.While their baseball skills improved over time with more practice, there were still problems with their all-important character. The team had a long way to go. For example, some boys were hard on those who made mistakes. Instead of being supportive or encouraging, they blamed (责怪) each other.Peter started one-on-one talks with each player to discuss things that he had noticed. Some were about skillslike holding the bat up higher or opening their eyes when they were making a catch. But most were about staying positive and supporting each other.Slowly things began to change. The boys began to take the duties for their play instead of blaming others for mistakes. They stayed optimistic even when losing. The team culture was improving.Players began encouraging each other, high-fiving and supporting teammates. Peter was especially pleased to see some of the boys taking leadership roles and having their own one-on-one talks with their teammates.Peter doesn’t think he made huge progress in teaching the boys how to throw, catch or hit better, but he was pleased that their conversations around character led to something positive. Although the team still lost games, the players had stronger characters. Next season, their characters will be tested again.19.When did Peter begin to help coach a school baseball team?A.Last spring. B.Last summer. C.Last autumn. D.Last winter.20.Paragraph 2 mainly tells us that the players had problems with their ________.A.baseball skills B.baseball bats C.characters D.training21.What does the underlined word “optimistic” in Paragraph 5 mean?A.精益求精的B.吹毛求疵的C.悲观的D.乐观的22.What can we infer from the passage?A.Peter’s efforts for the team work.B.The team will win the next season.C.The coach of the team wants to leave.D.They’ll be many fights among the boys.(2022·江苏无锡·统考中考真题)Lupe Medrano, a shy girl, was a straight-A student. Though Lupe had a sharp mind, she could not, no matter how much she tried, run as fast as the other girls. The truth was that Lupe was no good in sports.“I’ll never be good at sports.” She felt angry one rainy day as she lay on her bed, looking at the shelf her father had made to hold her awards. “I wish I could win something, anything, even marble(弹珠).”At the word “marbles”, she sat up. “That’s it. Maybe I could be good at playing marbles, and marbles is a sport.” She rushed out of her room and found the marbles in her brother’s room.She practiced shooting softly at first. The marble rolled from her thumb(拇指) and clicked against the targeted(作为目标的) marble. But the target wouldn’t budge. She tried again and again, but the power from her thumb made the targeted marble roll only an inch or two.She realized her thumb was weak and then decided to squeeze(捏) a rubber eraser one hundred times, hoping it would strengthen her thumb.The weeks passed quickly. Lupe worked so hard that one day, while she was drying dishes, her mother asked why her thumb was swollen(肿胀的).“It’s muscle,” Lupe explained, “I’ve been practicing for the marbles championship.”“You, honey?” Her mother, Mrs. Medrano, knew Lupe was no good in sports.“Yeah, I beat Alfonso, and he’s pretty good.”When her father, Mr. Medrano, heard this, he was very happy and encouraged Lupe.Practice, practice, practice. Lupe got better and better. Then the day of the championship came. She beat her first competitor easily, and won one marble, and then one after another. At last, Lupe was in the final to play against a girl in a baseball cap. The girl never even looked at Lupe.“I don’t know, Dad. She looks tough.”“You can do it,” her father encouraged. “Just think of the marbles, not the girl, and let your thumb do the work.”It was a tough fight. But finally Lupe won the most marbles and became the winner!“I did it!” Lupe said under her breath. She rose from her knees, which hurt from bending all day, and hugged her father.Back home, in her own bedroom, she was happy. She had always won praise because of her brains, but winning in sports was a new experience. She thanked her tired thumb. “You did it, thumb. You made me champion.” As its reward, Lupe went to the bathroom, filled the bathroom sink with warm water, and let her thum b swim as it pleased. Then she climbed into bed and fell into her sweet dreams.23.What does the underlined word “budge” mean in this story?A.Jump. B.Spin. C.Float. D.Move.24.How did Lupe feel when she saw the girl in a baseball cap?A.Sad. B.Ashamed. C.Curious. D.Worried.25.Which is the best title for this story?A.The Thumb. B.A Sharp Mind.C.The Marbles. D.A New Experience.阅读理解之记叙文1、记叙文是以记叙、描写为主要表达方式,以记人、叙事、写景、状物为主要内容的文章,简单点说就是记录事情从开始到经过到结果的文章。
专题14状语从句-2023年中考英语总复习真题探究与变式训练(全国通用)
Why do you want a new job when you’ve got such a good one already?
你已经找到如此好的工作,为何还想再找新的? (get 为短暂性动词)
Sorry, I was out when you called me.
对不起,你打电话时我刚好外出了。 (call 为短暂性动词)
has stopped.”可知,应该等到车停了再下车,用 until 引导时间状语从句,故选 A。
例 6(2022·湖南岳阳·统考中考真题)(as soon as 引导)I will return it to the library _______ I finish reading
Little Women.
You’ll fall behind the others unless you study hard. 如果你不努力学习,你将会落后于其他人。
2. when,while,as 引导时间状语从句的区别
when,while,as 显然都可以引导时间状语从句,但用法区别非常大。
① when 可以和延续性动词连用,也可以和短暂性动词连用;而 while 和 as 只能和延续性动词连用。
【变式 1】(2022·吉林长春·统考模拟预测)I love to listen to rock music ________ I am running.
A.while
A.no longer
B.as soon as
C.so that
【答案】B
【详解】句意:我一看完《小妇人》,我就把它还到图书馆。
考查状语从句。no longer 不再;as soon as 一……就……;so that 以便。根据“I will return”及“I finish reading”
【中考英语总复习 江苏专用 真题探究与变式训练】专题04 介词(原卷版)
专题04 介词命题方向重要指数(必考点)考向一时间介词、方位介词和方式介词考向二介词短语和固定搭配(常考点)考向一时间介词、方位介词和方式介词例1(2022·江苏淮安·中考真题)(时间介词on)—Mrs Wang, when is World Reading Day? —It is ________ April 23 every year.A.in B.at C.on D.by例2(2022·江苏南通·中考真题)(时间介词at)Now students have more free time ________ night because of the “double reduction” policy.A.in B.on C.at D.to例3(2022·江苏镇江·中考真题)(时间介词in)The traditional Chinese lunar calendar divides a year into 24 solar terms. Xiaoman(a little full) usually falls _______ May.A.in B.at C.on D.to例4(2017·江苏徐州·中考真题)(地点介词through)A bird flew into the kitchen the window.A.across B.above C.through D.under例5(2015·江苏苏州·九年级期末)(地点介词over, in)-Look at this picture. There is a bridge_______ the river, and there are three birds_______ the tree.A.on; in B.over; onC.over; in D.on; on例6(2022·江苏·扬州市江都区实验初级中学三模)(方式介词by)— Why have you done so well in the Maths exam, Annie?—To tell you the truth, I’ve made great progress ________ working in a group since last year. A.by B.with C.at D.on例7(2022·江苏无锡·一模)(方式介词through)The ancient Greeks succeeded in capturing the city ________ a trick in only one night.A.in B.through C.of D.for例8(2020·江苏·景山中学九年级期中)(方式介词with)The murderer killed the man________ a knife ________ the evening of December 10th.A.use; on B.using; in C.with; on D.with; in时间介词1)at, in onat:多用于表示具体的钟点时刻前或固定搭配at noon, at midnight, at night, at lunchtime。
【真题探究与变式训练】专题10西半球的国家和极地地区(原卷版)
主题二世界地理专题10 西半球的国家和极地地区中考命题方向考向一美国考向二巴西考向三极地地区考向一美国例1(2022·内蒙古)读甲、乙两个国家部分区域图,完成下面1-2小题。
1.关于甲、乙两国说法正确的是()A.甲国因地制宜发展养羊业,形成三个不同牧羊带B.甲国是世界矿产品的主要出口国之一,生产的矿产品主要销往欧洲国家C.乙国原住民是黑种人D.乙国的高新技术产业中心“硅谷”分布在其国家的东北部工业区2.甲、乙两国出口量较大的农产品是()A.咖啡B.稻谷C.小麦D.天然橡胶例2(2022·湖南怀化)图1为北美洲简图,图2为美国农业分布图。
读图,完成下面3-4小题。
3.北美洲西部温带海洋性气候呈南北狭长分布,主要影响因素是()A.地形地势因素B.纬度因素C.海陆位置D.人类活动4.美国农业因地制宜,图2反映出美国农业生产的____特点。
()A.机械化B.商品化C.区域专门化D.技术化例3(2022·甘肃陇南)下图为“美国本土地区”简图。
读图完成下面5-6小题。
5.密西西比河是美国最大的河流,该河流()A.由低纬流向高纬B.沿岸多热带雨林C.干流主要流经中央大平原D.越往下游河流结冰期越长6.美国东北部工业发达,其钢铁工业发展最主要的资源条件是()A.充足的水资源B.丰富的煤铁资源C.丰富的海洋资源D.廉价的劳动力资源例4(2022·江苏连云港)下图为“美国本土农业带分布图”。
读图完成下面7-8小题。
7.③为()A.水果和灌溉农业区B.亚热带作物带C.小麦和林牧业区D.乳畜带8.农业带③形成的主要优势条件是()A.水源丰富B.劳动力充足C.市场广阔D.地形平坦例5(2022·广西梧州)下图是“美国本土示意图和局部地区农业带分布图”,读图回答下列问题。
(1)山脉A的走向是____,山脉B是由太平洋板块和美洲板块____形成的;根据密西西比河的流向,判断中央平原的地势是____。
【中考英语总复习 江苏专用 真题探究与变式训练】专题06 形容词和副词(原卷版)
专题06 形容词和副词命题方向重要指数考向一形容词和副词的基本用法(必考点)考向二形容词和副词的词义辨析(常考点)考向三形容词和副词的原级、比较级和最高级(重难点)考向一形容词和副词的基本用法例1(2019·江苏·中考真题)(形容词作表语,副词修饰动词)In the library, students are required to keep ___________ and move ____________.A.quiet; quiet B.quiet; quietly C.quietly; quiet D.quietly; quietly例2(2019·江苏泰州·中考真题)(形容词作表语修饰系动词)-How about the fruit salad? -Yummy! It tastes very _________. By the way, who made it?A.good B.bad C.well D.badly例3(2022·江苏宿迁·中考真题)(形容词+enough)Amy did very well in her report. She is ________ to pay attention to every detail.A.enough careful B.careful enough C.enough careless D.careless enough形容词和副词的基本用法一、形容词的用法及位置说明人或事物的特征、性质或状态,常用来修饰名词或不定代词的词叫形容词。
1. 形容词作定语1)放在名词的前面。
如:delicious food 美味的食物2)放在不定代词的后面。
如:I have something important to tell you. 我有些重要的事情要告诉你。
3)形容词+enough,意思为“足够……的”,如:big enough 足够大注意:多个形容词修饰名词时,其顺序是:限定词—数词—描述性的词(大小,长短,形状,新旧,颜色)—出处—材料性质—类别—名词。
2022年山西省晋中市中考真题变式题6-10
2022年山西省晋中市中考真题变式题6-10一、单选题1. 科学家发现,除去p53基因的小鼠会在发育早期形成肿瘤。
这一事实说明()A.基因就是性状B.基因控制性状C.环境影响性状D.p53基因可诱发肿瘤形成2. 关于基因、性状及其关系的描述,正确的是A.基因相同,性状一定相同B.具有隐性基因的个体,都表现为隐性性状C.性状相同,基因组成可能不同 D.生物体表现出的性状都为显性性状3. 下图表示兔体细胞中的一对染色体及其上的一对基因。
下列与此有关的叙述错误的是A.图中D表示显性基因,d表示隐性基因B.如果D来自父方,则d来自母方C.此个体会表现D所控制的性状D.D和d分别控制两个不同的性状4. 有一种苏云金杆菌能产生杀虫毒素,科学家将控制这一杀虫毒素合成的基因成功地导入棉细胞中,获得具有抗虫性能的转基因棉。
下列有关分析错误的是()A.转基因棉的成功说明基因控制生物的性状B.杀虫毒素基因是有遗传效应的DNA片段C.转基因技术只能用于植物,不能用于动物D.转基因棉细胞的染色体数目没有改变5. 同一株水毛莨生长在水中的叶呈丝状,生长在水面的叶呈扁平状,这种性状的不同说明了()A.生物的性状完全由环境因素控制B.环境因素引起了基因的重新组合C.环境因素影响生物性状,基因不能影响生物性状D.这种性状的不同是基因和环境条件共同作用的结果6. 图所示,左边是小浣熊,右边是貉子,光看脸貉和小浣熊简直就像亲兄弟,但是从分类角度讲,貉是食肉目犬科,跟浣熊科差别很大,二者长相像“双胞胎”最合理的原因是()A.有亲缘关系的结果B.自然界中的巧合C.相同环境自然选择的结果D.两种动物主动变异的结果7. 种植在新疆阿克苏地区的红富土苹果,因该地区昼夜温差大,果实内糖分积累多,形成了特有的结晶体,故名“冰糖心”。
下列相关叙述正确的是()A.新疆阿克苏苹果的基因一定发生了改变B.新疆阿克苏苹果的性状只由基因决定C.新疆阿克苏苹果发生的变异一定是可遗传的变异D.新疆阿克苏苹果的性状表现是基因和环境共同作用的结果8. 2021年6月24日《细胞(Cell)》杂志报道,我国科学家黄三文团队培育出一种用种子繁殖的杂交马铃薯新品种——“优薯1号”。
专题69 数与式中的新定义问题(原卷版)-2023年中考数学重难点解题大招复习讲义-新定义问题
例题精讲【例1】.定义一种新运算:,例如.若,则k=.变式训练【变1-1】.定义:对于实数a,符号[a]表示不大于a的最大整数.例如:[5.7]=5,[5]=5,[﹣π]=﹣4,如果,则x的取值范围是()A.5≤x<7B.5<x<7C.5<x≤7D.5≤x≤7【变1-2】.规定:符号[x]叫做取整符号,它表示不超过x的最大整数,例如:[5]=5,[2.6]=2,[0.2]=0.现在有一列非负数a1,a2,a3,…,已知a1=10,当n≥2时,a n=a n﹣1+1﹣5([]﹣[]),则a2022的值为.【例2】.定义:如果一个数的平方等于﹣1,记为i2=﹣1,这个数i叫做虚数单位,把形如a+bi的数叫做复数,其中a叫做这个复数的实部,b叫做这个复数的虚部.它的加、减、乘法运算与整数的加、减、乘法运算类似.例如计算:(4+i)+(6﹣2i)=4+6+i﹣2i=10﹣i(2﹣i)(3﹣i)=6﹣2i﹣3i+i2=6﹣5i﹣1=5﹣5i根据以上信息计算(1+2i)(2﹣i)+(2﹣i)2=.变式训练【变2-1】.贾宪是生活在北宋年间的数学家,著有《黄帝九章算法细草》《释锁算书》等书,但是均已失传.所谓“贾宪三角”指的是如图所示的由数字所组成的三角形,称为“开方作法本源”图,也称为“杨辉三角”.贾宪发明的“开方作法本源“图作用之一,是为了揭示二项式(a+b)n(n=1,2,3,4,5)展开后的系数规律,即(a+b)1=a+b,(a+b)2=a2+2ab+b2,(a+b)3=a3+3a2b+3ab2+b3,(a+b)4=a4+4a3b+6a2b2+4ab3+b4,(a+b)5=a5+5a4b+10a3b2+10a2b3+5ab4+b5.则二项式(a+b)n(n为正整数)展开后各项的系数之和为()A.2n﹣1+1B.2n﹣1+2C.2n D.2n+1【变2-2】.已知n行n列(n≥2)的数表中,对任意的i=1,2,…,n,j=1,2,…,n,都有a ij=0或1.若当a st=0时,总有(a1t+a2t+…+a nt)+(a s1+a s2+…+a sn)≥n,则称数表A为典型表,此时记表A中所有a ij的和记为S n.(1)若数表,,其中典型表是;(2)典型表中S5的最小值为.1.对任意两个实数a,b定义两种运算:a⊕b=,a⊗b=,并且定义运算顺序仍然是先做括号内的,例如:(﹣2)⊕3=3,(﹣2)⊗3=﹣2,((﹣2)⊕3)⊗2=3⊗2=2,则等于()A.B.3C.D.22.对于两个不相等的实数a、b,我们规定符号Min{a,b}表示a、b中较小的值,如Min{2,4}=2,按照这个规定,方程Min{}=的解为()A.1或3B.1或﹣3C.1D.33.定义:如果a x=N(a>0,a≠1),那么x叫做以a为底N的对数,记做x=log a N.例如:因为72=49,所以log749=2;因为53=125,所以log5125=3.则下列说法正确的个数为()①log61=0;②log323=3log32;③若log2(3﹣a)=log827,则a=0;④log2xy=log2x+log2y(x>0,y>0).A.4B.3C.2D.14.我们把称作二阶行列式,规定它的运算法则为=ad﹣bc.如=2×5﹣3×4=﹣2,请你计算的值为.5.对于实数a,b,定义运算“◎”如下:a◎b=(a+b)2﹣(a﹣b)2.若(m+1)◎(m ﹣2)=16,则m=6.设n为正整数,记n!=1×2×3×4×…×n(n≥2),1!=1,则+++…++=.7.新定义:任意两数m,n,按规定y=﹣m+n得到一个新数y,称所得新数y为数m,n 的“愉悦数”.则当m=2x+1,n=x﹣1,且m,n的“愉悦数”y为正整数时,正整数x 的值是.8.对数的定义:一般地,若a x=N(a>0且a≠1),那么x叫做以a为底N的对数,记作x=log a N,比如指数式23=8可以转化为对数式3=log28,对数式2=log636,可以转化为指数式62=36.计算log39+log5125﹣log232=.9.对于正整数m,我们规定:若m为奇数,则f(m)=3m+3;若m为偶数,则f(m)=.例如f(5)=3×5+3=18,f(8)==4.若m1=1,m2=f(m1),m3=f(m2),m4=f(m3),…,依此规律进行下去,得到一列数m1,m2,m3,m4,…,m n,…(n为正整数),则m1+m2+m3+…+m2021=.10.如图,把平面内一条数轴x绕原点O逆时针旋转角θ(0°<θ<90°)得到另一条数轴y,x轴和y轴构成一个平面斜坐标系.规定:过点P作y轴的平行线,交x轴于点A,过点P作x轴的平行线,交y轴于点B,若点A在x轴上对应的实数为a,点B在y轴上对应的实数为b,则称有序数对(a,b)为点P的斜坐标.(1)点P(x,y)关于原点对称的点的斜坐标是;(2)在某平面斜坐标系中,已知θ=60°,点P的斜坐标为(2,4),点N与点P关于x 轴对称,则点N的斜坐标是.11.欧拉是18世纪瑞士著名的数学家,他的贡献不仅遍及高等数学的各个领域,在初等数学中也留下了他的足迹.下面是关于分式的欧拉公式:=(其中a,b,c均不为零,且两两互不相等).(1)当r=0时,常数p的值为.(2)利用欧拉公式计算:=.12.任何一个正整数n都可以进行这样的分解:(s、t是正整数,且s≤t),如果在n的所有这种分解中两因数之差的绝对值最小,我们就称是n的最佳分解,并规定:F(n)=.例如18可以分解成1×18,2×9,3×6这三种,这时就有F(18)==.给出下列关于F(n)的说法:①F(2)=;②F(48)=;③F(n2+n)=;④若n非0整数,则F(n2)=1,其中正确说法的是(将正确答案的序号填写在横线上).13.对于三个实数a,b,c,用M{a,b,c}表示这三个数的平均数,用min{a,b,c}表示这三个数中最小的数.例如:M{1,2,9}==4,min{1,2,﹣3}=﹣3,min{3,1,1}=1.请结合上述材料,解决下列问题:(1)min{sin30°,cos60°,tan45°};(2)若M{﹣2x,x2,3}=2,求x的值.14.定义为二阶行列式,规定它的运算法则为:=ad﹣bc.例如:=5×8﹣6×7=﹣2.(1)求的值.(2)若=20,求m的值.15.材料:对于一个四位正整数m,如果满足百位上数字的2倍等于千位与十位的数字之和,十位上数字的2倍等于百位与个位的数字之和,那么称这个数为“相邻数”.例如:∵3579中,2×5=3+7=10,7×2=5+9=14,∴3579是“相邻数”.(1)判断7653,3210是否为“相邻数”,并说明理由;(2)若四位正整数n=1000a+100b+10c+d为“相邻数”,其中a,b,c,d为整数,且1≤a≤9,0≤b≤9,0≤c≤9,0≤d≤9,设F(n)=2c,G(n)=2d﹣a,若为整数,求所有满足条件的n值.16.我国宋朝数学家杨辉在他的著作《详解九章算法》中提出“杨辉三角”(如图),此图揭示了(a+b)n(n为非负整数)展开式的项数及各项系数的相关规律.例如:(a+b)0=1,它只有一项,系数为1;(a+b)1=a+b,它有两项,系数分别为1,1,系数和为2;(a+b)2=a2+2ab+b2,它有三项,系数分别为1,2,1,系数和为4;根据以上规律,解答下列问题:(1)(a+b)5展开式共有项,系数和为.(2)求(2a﹣1)5的展开式;(3)利用表中规律计算:25﹣5×24+10×23﹣10×22+5×2﹣1(不用表中规律计算不给分);(4)设(x+1)17=a17x17+a16x16+…+a1x+a0,则a1+a2+a3+…+a16+a17的值为.17.若规定f(n,m)=n×(n+1)×(n+2)×(n+3)×…×(n+m﹣1),且m,n为正整数,例如f(3,1)=3,f(4,2)=4×5,f(5,3)=5×6×7.(1)计算f(4,3)﹣f(3,4);(2)试说明:;(3)利用(2)中的方法解决下面的问题,记a=f(1,2)+f(2,2)+f(3,2)+…+ f(27,2),b=f(1,3)+f(2,3)+f(3,3)+…+f(11,3).①a,b的值分别为多少?②试确定a b的个位数字.18.请阅读以下材料,解决问题.我们知道:在实数体系中,一个实数的平方不可能为负数,即a2≥0.但是,在复数体系中,如果一个数的平方等于﹣1,记为i2=﹣1,这个数i叫做虚数单位,那么形如a+bi (a、b为实数)的数就叫做复数,a叫做这个复数的实部,b叫做这个复数的虚部.它的加,减,乘法运算与整式的加,减,乘法运算类似,例如计算:(3+i)i=3i+i2=3i﹣1(2+i)+(3﹣4i)=(2+3)+(1﹣4)i=5=3i;若两个复数,它们的实部和虚部分别相等,则称这两个复数相等;若它们的实部相等,虚部互为相反数,则称这两个复数共轭,如1+2i的共轭复数为1﹣2i.根据材料回答:(1)填空:①(2+i)(3i﹣1)=;②将m2+9(m为实数)因式分解成两个复数的积:m2+9=;(2)若a+bi是(1+2i)2的共轭复数,求(b﹣a)2022的值;(3)已知(a+i)(b+i)=2﹣4i,求(a2﹣b2)(i2+i3+i4+…+i2023)的值.19.式子“1+2+3+4+…+100”表示从1开始的连续100个正整数的和,由于上述式子比较长,书写不方便,为了简便起见,可以将上述式子表示为,这里“∑”是求和的符号.例如“1+3+5+7+…+99”用“∑”可以表示为,“13+23+33+…+103”用“∑”可以表示为.(1)把写成加法的形式是;(2)“2+4+6+8+…+100”用“∑”可以表示为;(3)计算:.20.好学的小贤同学,在学习多项式乘以多项式时发现:(x+4)(2x+5)(3x﹣6)的结果是一个多项式,并且最高次项为:x•2x•3x=3x3,常数项为:4×5×(﹣6)=﹣120,那么一次项是多少呢?要解决这个问题,就是要确定该一次项的系数.根据尝试和总结他发现:一次项系数就是:×5×(﹣6)+2×(﹣6)×4+3×4×5=﹣3,即一次项为﹣3x.请你认真领会小东同学解决问题的思路,方法,仔细分析上面等式的结构特征.结合自己对多项式乘法法则的理解,解决以下问题.(1)计算(x﹣5)(3x+1)(5x﹣3)所得多项式的一次项系数为.(2)若计算(x2+x﹣1)(x2﹣2x+a)(2x+3)所得多项式的一次项系数为2,求a的值;(3)若(x+1)2022=a0x2022+a1x2021+a2x2020+…+a2021x+a2022,则a2021=.21.阅读下列材料.材料一:对于一个四位正整数,如果百位数字大于千位数字,且个位数字大于十位数字,则称这个数是“双增数”;如果百位数字小于千位数字,且个位数字小于十位数字,则称这个数是“双减数”.例如:3628、4747是“双增数”,5231、9042是“双减数”.材料二:将一个四位正整数m的百位数字和十位数字交换位置后,得到一个新的四位数m',规定:F(m)=m﹣m',例如:F(2146)=2146﹣2416=﹣270.(1)最大的“双增数”是,最小的“双减数”是;(2)已知“双增数”s=1000x+100(y+4)+10y+6(1≤x≤9,0≤y≤9,x、y是整数),“双减数”t=3000+20a+b(0≤a≤9,0≤b≤9,a、b是整数),且t的各个数位上的数字之和能被12整除,现规定k=F(s)+F(t),求k的最大值.。