八年(下)顶尖学案错题

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八年级下册易错题第一章 三角形的证明1.已知等腰三角形的两边长分别为5㎝、2㎝，则该等腰三角形的周长是(D )A ．7㎝B ．9㎝C ．12㎝或者9㎝D ．12㎝考查知识点：三角形的基本知识及等腰三角形边的关系：任意两边之和大于第三边，等腰三角形两腰相等，因此只能是：5cm ，5cm,2cm 。

2。

一个等腰三角形的一个角是40°,则它的底角是（D ）A ．40°B ．50°C ．60°D ．40°或70°考查知识点：三角形的内角和及等腰三角形两底角相等：①当40°是顶角时，底角就是70°；②40°就是一个底角。

3。

已知△ABC 的三边长分别是6cm 、8cm 、10cm ，则最长边上的高是（D ）A 。

2。

4cmB 。

3cm C.4cmD 。

4。

8cm提示：设最长边上的高为h ，由题意可得△ABC 是直角三角形，利用面积相等求，即h .10.218.6.21 解得h=4.84。

等腰三角形一腰上的高与另一腰的夹角为300,腰长为6，则其底边上的高是3或33。

解：①三角形是钝角三角形时，如图1，∵∠ABD=30°∴AD=21AB=21×6=3， ∵AB=AC ，∴∠ABC=∠ACB=21∠BAD=21(90°-30°)=30°， ∴∠ABD=∠ABC,∴底边上的高AE=AD=3；②三角形是锐角三角形时，如图2，∵∠ABD=30°∴∠A=90°—30°=60°，∴△ABC 是等边三角形， ∴底边上的高为23×6=33 综上所述,底边上的高是3或335.到三角形三个顶点的距离相等的点是三角形（B )的交点。

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D71．（2013•日照）某型号天燃气泄漏检测仪器的电路如图甲所示，图中R为气敏电阻，其阻值R与天然气浓度β的变化关系如图乙所示，已知R0为定值电阻，电源电压恒定不变，用此仪器检测天然气是否泄漏，则下列判断正确的是（）72．某同学使用手电筒时发现小灯泡不亮，在进行检修前，他对造成该现象的直接原因进行了以下几种判73．（2008•宜宾）在如图所示的电路中，电源电压和灯泡电阻都保持不变，当滑动变阻器的滑片由中点向右移动时，下列判断中正确的是（）74．如图所示是一个环境温度监控电路原理图．电源电压不变，R0为定值电阻，R是用半导体材料制成的热敏电阻，其电阻值会随温度的升高而变小．若环境温度升高，闭合开关S，则（）75．如图所示的电路中，闭合开关，滑动变阻器滑片向右滑动的过程（）76．（2012•南充）如图所示的电路，当开关S闭合后（）77．如图所示，验电器甲带负电，箔片张开一定的角度，乙不带电，用一根带绝缘柄的铜棒连接两验电器，则下列有关判断正确的是（）78．用某电源供电，当电源的放电电流为5A时，可持续放电150s，若希望持续放电375s，则放电电流应79．如图所示，灯泡L1、L2串联在电路中，开关闭合后两个灯泡都不亮．用电压表测L1两端电压时，其示数为0；再用电压表测L2两端的电压时，其示数为6V．则灯泡L1、L2的状况是（）80．（2010•无锡一模）在电学实验中遇到断路时，常常用电压表来检测，某同学连接如图所示的电路，开关闭合后，电灯不亮，电流表无指示．这时用电压表测得a、b两点间和b、c两点间的电压均为零，而b、d间的电压不为零，这说明（）81．甲、乙两人站在一堵光滑的墙壁前，两人之间相距102m，且距离墙壁均为68m，如图所示，甲开了一枪后，乙先后听到两声枪响的时间间隔为（）（已知空气中声音的传播速度为340m/s）82．在两块夹角为α的平面镜A和B的镜面前方对角线上有一点光源，欲使点光源和它在两平面镜中的83．如图所示，一束与主光轴平行的光束宽度为a，照射到一个焦距为f的凸透镜上，在凸透镜后面放一个垂直于主轴的光屏，测得在光屏上形成光斑的宽度为b，则光屏到凸透镜的距离为（）85．如图所示，甲、乙、丙为直径不等的三个金属球，甲带正电，乙、丙均不带电，现将乙、丙球接触，甲球接近乙球但不接触，然后把乙、丙球分开，再移去甲球，则（）86．（2010•烟台）在今年理化生实验技能测试中，实验室准备的器材有：电源、电压表、电流表、滑动变阻器、开关、待测电阻及导线若干．在做测电阻的实验时，小明在连接电路过程中，由于疏忽，把电压表发现电压表V2的示数变大，则（）88．（2012•肇庆模拟）小明同学做电学实验，通过改变滑动变阻器R3电阻的大小，依次记录的电压表和开关后，电路可能发生的现象是（）1292．如图所示的电路中，当开关S断开时，下列说法正确的是（）换为6Ω后，他下一步的操作是（）阻器上标有“15Ω 1A”字样．在a、b间先后接入不同阻值的定值电阻，移动滑片P，使电压表示数为1.5V，读出电流表的示数．当20Ω的电阻接入a、b间时，电压表示数始终无法达到1.5V，其原因可能是（）二．填空题（共6小题）95．如图所示，用均匀的电阻丝围成的一个正方形ABCD，其中E为CD边的中点，现分别将AB，AC和AE接在同一个电源上，则三次通过电源的电流之比为_________．96．灯L1与灯L2串联，先用电压表测灯L1两端的电压，如图所示再测灯L2两端的电压时，只将电压表接A的一端改接C，这种接_________（填“正确”或“不正确”．原因是_________．97．（2012•抚顺）如图所示，电源电压不变，闭合开关S后，滑动变阻器的滑片从a向b移动的过程中，电流表A的示数_________，电压表V1的示数_________，电压表V2与电流表A示数的比值_________．（选填“变大”、“变小”或“不变”）98．如图所示的电路中，电源电压不变，闭合开关S1、S2，电压表示数为U1；接着只断开开关S2，此时电压表示数为U2，若已知U1：U2=5：3，则电阻R1和R2的阻值之比是_________．99．（2009•房山区一模）在如图所示的电路中，电源电压保持不变，闭合开关S后，当滑片P向左移动时，电流表示数将_________（选填“变大”、“变小”或“不变”）．当滑片P分别在滑动变阻器的两个端点a和d、中点c和点b四个位置时，电压表示数从小到大顺序分别为0V、2V、3V和4V，电流表的示数从小到大分别为0.1A、0.15A、0.2A、0.3A．则在图示b位置时电压表示数应为_________V，该实验中R 的电阻为_________Ω．100．（2013•广安）小明在实验室设计如图所示的电路测量电阻R的阻值．已知R0=20Ω，S1、S2都闭合时，电压表示数为6V，只闭合S1时，电压表示数接近6V，电路可能出现的故障是_________．小明检查电路排除故障后，只闭合S1时，电压表示数为2V，则R的阻值为_________．101．（2012•河南）如图所示，在研究凸透镜成像规律的实验中，光屏上呈现了烛焰倒立清晰的像．如果去掉光屏，眼睛在A 处_________（选填“能”或“不能”）看到这个像，原因是_________．102．（2013•云南）如图所示为分别测量小灯泡L和定值电阻R后得到的I﹣U关系图线．由图可知，随着电压的升高，L的阻值逐渐变_________，R的阻值为_________Ω．103．入射光线与反射光线的夹角是60°，若使入射光线向镜面靠近10°，则入射光线和反射光线的夹角应当是_________；为了使和水平方向成50°角的阳光竖直射入井里，那么平面镜的反射面和水平面应成_________度角放置；如果太阳光与水平方向夹角增加20°角，仍使阳光竖直射入井里，则平面镜再转_________度角．104．小明到湖边游玩，他站在岸上看到了：①岸上的树，②水中的鱼，③空中的小鸟，④自己在水中的倒影．则在小明看到的景物中，属于光的反射形成的是_________，属于光的折射形成的是_________（填序号）105．（2012•德州）现在许多宾馆都利用房卡取电，如图所示．只有把房卡插入槽中，房间内的用电器才能使用．房卡的作用相当于家庭电路中的_________，房间里各用电器之间是_________联的．106．（2012•内江）如图所示，是发光二级管的示意图．当电流从较长的接线脚流入时，发光二极管中有电流通过，使其发光；如果电流从较短接线脚流入，电流处于_________（选填“短路”或“开路”）状态，这说明发光二极管具有_________导电性．107．如图所示的电路中，当开关S闭合，S1、S2断开时，灯泡_________串联；当开关S、S1、S2均闭合时，灯泡_________并联．108．如图1所示，在一根横跨河流两岸的硬塑料管内穿有三根完全相同的电线．为辨别哪两个线头为同一根导线，可用如图2所示的测通器来测试．连接A和B，将测通器的m端连接在D上，当n连接F时小灯泡发光，连接E时小灯泡不发光．由此可确定_________为同一根导线．109．（2012•厦门）在如图所示的电路中，电源电压保持不变．闭合开关S，电路正常工作．一段时间后，发现电表的示数发生了变化，已知电路中只有一处故障，且发生在电阻R1或R2上．若两个电表的示数都变大，发生的故障是_________；若一个电表示数变大，另一个电表示数为0，则发生故障的电阻是_________．120．在“研究凸透镜成像”的实验中，点燃的蜡烛分别放在a、b、c、d、e五个位置，如图所示，其中蜡烛放在_________处所得的实像最大，放在_________处能看到正立放大的像．若在实验中发现光屏上成的烛焰像偏左，为了使烛焰像能成在光屏中央，应向_________调烛焰位置（选填“上”、“下”、“左”、“右”）．121．（2012•苏州）敲击鼓面，在听到鼓声时，还可看见鼓面上小纸团在跳动，说明鼓声是由于鼓面的_________产生的；鼓面的_________越大，鼓声的响度越大．122．二胡发出动听的声音是_________在振动，用嘴对着笔套吹气发出的声音是_________在振动．123．减弱噪声的三种途径是_________，_________，_________．124．某同学身高1.7m，站在竖直放置的平面镜前1.5m处，他的像高是_________，他的像到平面镜的距离是_________．125．平面镜的作用是：可以_________，还可以_________光的传播方向．潜望镜是利用了平面镜_________的性质；平静的水面、抛光的金属表面都具有_________的性质，都能成_________立、等大的_________像．126．一根阻值为R=27Ω的粗细均匀的电阻线弯成一个圆，A、B、C是三等分点，如图所示．若将AB接在5.4V的电源上，则整个电路中的电流为_________A．127．当把笔尖触到平面镜上时，看到笔尖的像与笔尖相距约4毫米，则该平面镜的厚度约为_________毫米．三．解答题（共3小题）128．（2013•泗阳县二模）热敏电阻的阻值会随温度的改变而改变，小芳同学用图甲所示的电路来探究某一热敏电阻Rr的阻值与温度的关系．已知M为控温器，电源电压恒为12V，R为电阻箱．（1）小芳在控温器中应该加入的液体是_________（选填煤油/食盐溶液）；（2）当控温器中液体温度为80℃，电阻箱阻值为100Ω时，电流表的示数为0.1A．则该温度下热敏电阻的阻值为_________Ω．（3）依次改变控温器中的液体温度，同时改变电阻箱的阻值，使电流表的示数始终保持在0.1A．通过计由数据可知：此热敏电阻的阻值随着温度的降低而_________．（4）小芳利用该热敏电阻和电压表制成了一支指针式温度计（电路如图乙）．它可以直接在电压表刻度盘上读出相应温度．若要求电压表的读数随温度的升高而增大，则她应在原理图（乙）中_________两端并接一电压表（在a、b、c中选择）．129．一辆汽车向山崖开去，在离山崖710m时司机按了一下喇叭，经过了4s他听到了回声，求：（1）当司机听到回声时离山崖多远？（2）汽车的速度是多少？130．如图：在平面镜前有A、B两发光点，要想通过镜子观看时，它们的像正好重叠，试画图说明应在什么方向观看？三．解答题（共4小题）131．将两盏相同的灯L1和L2串联或并联后，直接接在电压为6V的电源上．两灯都发光．请根据下列操（1）用导线连接A、B，则电流通过灯_________，它们是_________联的；（2）用导线只连接C、D，则电流通过灯_________，它们是_________联的．133．（2008•烟台）某电路中有一个封闭的电路盒如图，面板上有A、B、C三个接线柱及灯泡、电铃各一个．为了探究盒内电路结构，小明做了多次实验，实验结果记录如下表．根据实验情况，请你在虚线框内134．（2013•常州）冬季夜间，婴儿踢开被子或尿床，若家长没有及时发现，将影响孩子健康，对此，常州工程职业技术学院的同学们分别展开实验探究，设计镶嵌在婴儿被中的“踢被警示电路”和“尿床警示电135．如图所示，有一竖直放置的平面镜MN，在平面镜前45cm处有一与平面镜平行放置的平板ab，在ab靠镜面的一侧有一点光源S，现要在离平面镜5cm的PQ虚线上的某一处放一平行于平面镜的挡光板，使反射光不能照射ab板上的AB部分，已知SA=45cm，AB=45cm，求挡光板的最小宽度CD是_________．136．如图所示，是探究平面镜成像特点的实验装置．在“探究平面镜成像的特点”实验中，某同学用玻璃板、相同的两个棋子A和B、刻度尺、白纸、橡皮泥等器材进行实验，（1）用玻璃板代替平面镜，主要是利用玻璃板透明的特点，便于_________；（2）如果有3mm厚和2mm厚的两块玻璃板，应选择_________mm厚的玻璃板做实验；（3 ）在寻找棋子A的像的位置时，眼睛应该在棋子_________（选填“A”或“B”）这一侧观察，移动玻璃板后的棋子B，使它与棋子A在玻璃板中所成的像重合；（4）实验中使用刻度尺，是为了测量_________；（5）移开棋子B，用白纸做屏幕放在该位置，直接观察白纸，能否看到A的像，可知平面镜所成的像是_________．137．将一根粗细均匀、阻值为90Ω的金属丝焊接成一个闭合的圆环，组成如图13所示的电路．其中a点为固定连接；b处是一个滑片，可在圆环上滑动且保持良好接触．电源电压为1OV不变．（1）这个电路实际上存在着安全隐患，请说明是什么隐患，会有怎样的不良后果．（2）当滑片b滑至点为三分之一圆周长位置时，求电流表的读数．（3）当滑片b滑到什么位置时，电流表的读数为最小？并求出最小值．138．某同学连好上题中所述电路后发现：将关断开时，两灯均发光，当开关闭合时，一盏灯发光，另一盏灯却熄灭了，试画出该同学所连接电路的电路图，他所连电路和错误是_________．。

错题精华集unit3 Could you please clean your room?一、单项选择(45分)1．(1分)—I am not good at English.—____.A.So am IB.Neither am IC.Neither I amD.So I am2．(1分)____ Lily ____ Lucy is going with you, because one of them must stay at home.A.Not only; but alsoB.Neither; norC.Both; andD.Either; or 3．(1分)We couldn't buy anything because ____ of the shops were open.A.allB.bothC.nothingD.none4．(1分)—Could you take out the rubbish and do the dishes, Tony?—Sure. Mom will be mad if she sees this ____, I think.A.matterB.messC.troubleD.difficulty 5．(1分)—Which do you prefer, rice or noodles?—____, thanks I am not hungry. I only need some water.A.NeitherB.EitherC.BothD.All6．(1分)I want to ____ some money from him, but he doesn't ____ it to me.A.borrow; lendB.lend; borrowC.borrow; returnD.borrow; borrow 7．(1分)—Luna runs slowly.—____A.So she is!B.Neither will I!C.So does Nick!D.Neither can Tom!8．(1分)—I can't see the picture well from here.—____.A.Neither can't IB.Neither I canC.I can't NeitherD.Neither can I 9．(1分)—Could you please ____ be late again?—Sorry, I won't be late again.A.to try notB.try not toC.try to not10．(1分)—David has made great progress recently.—____, and ____.A.So he has; so you haveB.So he has; so have youC.So has he; so have you 11．(1分)—Why do you like travelling to Kunming for a holiday?—Because the weather there is ____ too hot ____ too cold.A.neither; norB.both; andC.not only; but alsoD.either; or12．(1分)—Tony, you must clean your room now.—Oh, mom. Why? I think it is ____.A.curlyB.tidyC.easyD.dirty13．(1分)As we are growing up, we should learn to take care of ____.A.weC.ourD.ourselves 14．(1分)My father was reading a newspaper ____ my mother was cooking dinner.A.whenB.whileC.as soon asD.until15．(1分)I think ____ easier to take care of a goldfish than a dog.A.it'sB.they'reC.we'reD.she's16．(1分)Children these days ____ their parents too much.A.belong toB.happen toC.depend onD.concentrate on 17．(1分)—Could you please pass me the book?—____.A.Yes, I couldB.No, I couldn'tC.Sure. Here you areD.No, that's no problem 18．(1分)—I'm not going swimming tomorrow afternoon.—____. I have to clean up my bedroom.A.So am IB.Neither am IC.Neither I amD.So I am19．(1分)One of the best ways for people to keep healthy is to____ good eating habits.A.developB.growC.findD.increase20．(1分)—Can I ____ your bike?—With pleasure. But you mustn't ____ it to others.A.lend; borrowB.borrow; lendC.lend; lendD.borrow; borrow 21．(1分)The building has ____ floors and our classroom is on the ____ floor.A.four; fourB.fourth; fourthC.four; fourth22．(1分)—Do you think I could borrow your pencil?—____.A.Yes, you may borrowB.Yes, you couldC.Yes, go onD.Yes, help yourself23．(1分)—Could I borrow your dictionary?—Yes, of course you ____.A.couldB.willC.canD.might24．(1分)—Great changes have taken place ____ we enter E-Times.—Yeah. I agree with you.A.beforeB.as soon asC.whenD.since25．(1分)—Oh, my god! Recently I have put on 5 pounds.—____. I think I should lose weight.A.So do IB.So have IC.Neither do ID.Neither have I 26．(1分)—Why do you ____ to read the book?—Because I think it is boring.A.likeB.hopeC.hateD.decide27．(1分)—Do you like Sichuan food?—Yes. My brothers and I ____ like hot food very much.A.allB.bothC.eitherD.neither28．(1分)—Could you please ____ your room, Tom?—____.A.cleaning; No problemB.clean; CertainlyC.to clean; Of courseD.clean; No, I couldn't29．(1分)—Are you going to Brazil to watch 2014 FIFA World Cup (2014年世界杯足球赛) this summer?—I'm not sure. It ____ time.A.depends onB.cares aboutC.agrees toD.finds out 30．(1分)—Could you please sweep the floor?—____. I have to do my homework.A.Yes, sureB.Why notC.Sorry, you can'tD.Sorry, I can't 31．(1分)Wu Yi will help with the housework ____ he gets home after school.A.sinceB.whileC.as soon as32．(1分)Rock music ____ sound popular with the young, but it's not the favor of the aged people.A.mustB.needC.shouldD.may33．(1分)Ladies and gentlemen, attention please! I have ____ important to tell you.A.nothingB.somethingC.everythingD.anything 34．(1分)—Must I go to law school and be a lawyer like you, Dad?—No, you ____, son. You're free to make your own decision.A.can'tB.mustn'tC.shouldn'tD.needn't35．(1分)We should be kind to the old and take care ____ them in daily life.A.ofB.forC.withD.about36．(1分)一How did the plate get ____? It's my favorite, you know.一Maybe you can ask Tom. He did the dishes just now.A.fullB.readyC.brokenD.clean37．(1分)My sister didn't sweep the floor. ____.A.So did IB.So was IC.Neither did ID.Neither was I 38．(1分)Neither my brother nor I ____ a doctor.A.isB.amC.areD.be39．(1分)—Could you please look after my daughter when I am away?—____.A.You're welcomeB.With pleasureC.It doesn't matterD.Good idea 40．(1分)Helen does well in her schoolwork. She studies hard ____.A.at timesB.all the timeC.on timeD.in time41．(1分)—Dad, must we wait until the light becomes green?—Yes, I'm afraid we ____. That's the traffic rule.A.canB.mayC.have toD.need42．(1分)I will send you an e-mail as soon as I ____ in Canada.A.arriveB.arrivedC.am arrivingD.will arrive 43．(1分)In many western countries, supermarkets can only provide customers ____ paper bags.A.withB.forC.toD.of44．(1分)—Alice's room is tidy, isn't it?—Yes. She always ____ her toys after playing with them.A.looks forB.puts awayC.sweeps awayD.pays for45．(1分)Could you please ____ me such boring questions? I'm tired.A.not askB.not to askC.not askingD.don't ask二、填空题(28分)46．(5分)根据汉语意思完成句子。

错题精华集unit8 Have you read Treasure Island yet?一、单项选择(45分)1．(1分)—Are those books ____?—No, they are not mine. They belong to ____.A.your; herB.yours; herC.your; hersD.yours; she 2．(1分)—Alex, go and clean your bedroom.—I ____ it. It's clean and tidy now.A.have cleanedB.cleanedC.have leftD.left3．(1分)—How many children does he have?—None, he is not married, he is ____ single.A.alreadyB.yetC.everD.still4．(1分)一Would you like ____ to eat?—No, thanks. I'm full.A.else somethingB.else anythingC.something elseD.anything else 5．(1分)—Have you seen ____ TV series Nirvana in Fire (《琅琊榜》), Mum? —Yes, it's quite ____ interesting play, so I have seen it twice.A.a;theB.the;anC.a; aD.the;the 6．(1分)I used to ____ to school, but now I'm used to ____ my bike to school.A.walk; rideB.walking; ridingC.walk; ridingD.walking; ride7．(1分)It's not easy to learn a foreign language, but I will never ____.A.give awayB.give offC.give upD.give out8．(1分)Diana has ____ fed the dog, but she hasn′t watered the flowers ____.A.already; alreadyB.yet; alreadyC.already; yetD.yet; yet9．(1分)His father has worked here ____ he came here.A.whenB.beforeC.sinceD.while10．(1分)Everyone in Britain ____ the story ____ Alice's Adventures in Wonderland.A.knew; calledB.knows; calledC.to know; callD.knowing; to call 11．(1分)You can't believe how terrible the fire is ____ you see it with your own eyes.A.thoughB.becauseC.unlessD.since12．(1分)In the library there ____ a number of books on science and the number of them ____ growing larger and larger.A.is; areB.are; isC.is; isD.are; are13．(1分)The rivers will become dirtier and dirtier ____ we take action to protect them.A.sinceB.ifC.untilD.unless14．(1分)—Which dress do you like best, madam?—Sorry, I can't decide ____ now.A.to buy which oneB.buy which oneC.which one to buyD.which I should buy it15．(1分)____ my cousin is very young, ____ she can help with the housework.A.Once; /B.Though; butC.Although; /16．(1分)—Has your friend finished his painting?—Not yet. Still he ____ on it at the moment.A.is workingB.has workedC.was workingD.worked17．(1分)David is a tennis player. He ____ to play tennis when he was six years old.A.beginsB.will beginC.beganD.has begun 18．(1分)—Paul, what were you doing at nine last night?—I ____ a movie in the cinema with my friends.A.was watchingB.watchC.have watchedD.will watch 19．(1分)—What do you think of the four classics (名著) of China?—They are wonderful, but I've read ____ of them.A.bothB.noneC.neitherD.all20．(1分)—Little Jenny looks unhappy today.—Don't worry. A box of chocolates will ____ her ____.A.give; upB.wake; upC.cheer; upD.pick; up 21．(1分)____ you've learned at least three languages well, you can talk with foreigners freely.A.BecauseB.WhenC.AlthoughD.Since22．(1分)—I'm sorry to ____ on you, but there are one or two things I don't understand.—It doesn't matter.A.cut downB.cut outC.cut inD.cut off23．(1分)—____ he ____ the driving test?—No, not yet.A.Did;passB.Does;passC.Have;passedD.Has;passed24．(1分)Miss Lin ____ a lot of work for the poor area in the past three years. A.does B.did C.has done D.will do 25．(1分)—Have you seen the movie Forever Young?—Yes. I ____ the movie with my friend last night.A.watchB.watchedC.watchesD.have watched 26．(1分)My brother will go abroad, so I'm going to the airport to ____.A.meet himB.see him offC.meet him offD.see off him 27．(1分)—____ you ____ your homework?—No, I ____. Wait for me a minute.A.Did; finish; didn'tB.Have; finished; haven'tC.Do; finished; don'tD.Have; finish; haven't28．(1分)—Have you ____ spoken to an Englishman?—No. I have ____ spoken to a foreigner. (外国人)A.never; everB.never; yetC.ever; everD.ever; never 29．(1分)Five kilometers ____ not very far, you can ride a bike there.A.isB.areC.wasD.be30．(1分)If you read a lot, your life will be full ____ fun.A.byB.ofC.forD.with31．(1分)I have read ____ books this month. The ____ one is the most interesting.A.third; twoB.three; twoC.third; secondD.three; second 32．(1分)—How many books does the library have?—About two ____.lionlionsC.thousands ofD.thousand of 33．(1分)Volunteers help with research and animal rescue, and they teach____ about sea life.A.otherB.othersC.the otherD.another 34．(1分)David gave two ____ his money to the poor children in the countryside.lions oflionlionslion of 35．(1分)My sister has learned English ____.A.for twelve years agoB.since she was fourC.twelve years agoD.at the ago of four36．(1分)Mark has got a few friends in his new school, ____?A.is heB.isn't heC.has heD.hasn't he 37．(1分)—Look out, there is a hole in front. Be careful ____ into it.—Thank you.A.not fallB.don't fallC.not to fallD.not falling 38．(1分)Jack as well as his parents ____ looking forward to going ____.A.is; abroadB.are; abroadC.is; to abroadD.are; to abroad 39．(1分)—Do you think it will be cool tomorrow?—____. It has been hot for a week.A.I hope soB.I'm afraid soC.So it isD.Of course not40．(1分)Wang Mei ____ Ann since a month ago.A.haven't seenB.hasn't seenC.didn't seeD.doesn't see41．(1分)Jen speaks good Chinese. She ____ the Chinese language at Beijing University for a year after she finished university in London.A.studiesB.is studyingC.has studiedD.studied 42．(1分)一Have you returned the book ____?一Yeah, I went to the library ____.A.yet; alreadyB.already; justC.yet; just nowD.already; before 43．(1分)____ people will go to the party. Do you know?lions oflon ofC.Five Millionslion 44．(1分)I don't like these two T-shirts. Could you please show me ____ one?A.the otherB.otherC.anotherD.others 45．(1分)When I was in New York last summer, I ____ in the hotel for a week.A.stayB.am stayingC.stayedD.have stayed二、填空题(21分)46．(5分)根据句意，用括号中所给词的适当形式填空。

初二下错题集物理：1、将木块轻轻放入盛有水的容器中，木块漂浮在水面上，溢出的水重0.2N，则木块重A. 大于0.2NB. 等于0.2NC. 小于0.2ND. 无法确定我的答案（B）标准答案（D）解析：容器中一开始是否盛满水未知，木块漂浮在水面上，溢出了一些水，如果水是盛满的，则木块受到的浮力等于溢出水的重0.2N，木块的重力等于0.2N；如果水未盛满，木块受到的浮力大于溢出水的重力。

选D。

我的答案（A）标准答案（B）解析：金属球的质量较大，惯性较大，原来处于静止状态，当用手向下猛拉小木棒时，金属球由于惯性仍保持原来的静止状态，金属球上面的细线受力还未增大时，下面的细线已被拉断。

选B。

3、小明同学喜欢动手用简易器材探究物理问题。

某天，他用一块较长的木板N与木块M及弹簧测力计，按如下方法研究滑动摩擦力与压力的关系。

先将长木板N平放，用弹簧测力计拉着木块M在N上做匀速直线运动，如图甲，此时木块M所受滑动摩擦力为f甲；然后再将N支起，仍然用弹簧测力计拉着木块M沿N斜向上做匀速直线运动，如图乙，此时木块M所受滑动摩擦力为f乙。

请你判断这两种情况下，木块M受到的滑动摩擦力大小关系是A．f甲＞f乙B．f甲＜f乙C．f甲= f乙D．f甲≤f乙我的答案（C）标准答案（A）解析：接触面的粗糙程度相同，甲情况下木板受的压力大小等于木块M的重力，乙情况下木板受的压力小于木块M的重力，所以f较小。

选A。

乙4、如图所示的容器中充满液体，将它倒置过来放在桌面上，跟原来比较，容器底部受到A．压力不变，压强变大B．压强不变，压力变大C．压力不变，压强不变D．压强不变，压力变小我的答案（A）标准答案（D）解析：因为容器中充满液体，将它倒置过来后水的深度不变，水对容器底部的压强不变，但底部受力面积变小，由F=pS可知，底部受到水的压力变小。

选D。

5、如下图所示，四个相同的容器内水面一样高，a容器内只有水，b容器内有木块漂浮在水面上，c容器内漂浮着一块冰块，d容器中悬浮着一个空心球。

新课标八年级英语下册易错题易错题以及答案+八年级下册英语单元知识点归纳新课标八年级下册英语单元知识点归纳Unti1 what’s the matter?短语归纳1.too much 太多2.lie down 躺下3.get an X-ray 做个X光检查4.take one ’s temperature 量体温5.put some medicine on ......在....上敷药6.have a fever 发烧7.take breaks /take a break 休息 8.without thinking twice 没多想9.get off 下车 10.take sb to the hospital 送某人去医院11.wait for等待 12.to one’s surprise 使.......惊讶的 thanks to多亏于；由于14.in time及时15.think about 考虑16.have a heart problem患有心脏病17.get into the trouble 遇到麻烦18.do the right thing做正确的事情事情19.fall down 摔倒20.put ...... on sth把...放在某物上 21.get hit/sunburned 摔伤/烧伤22.be interested in 对.....感兴趣 23.be used to 习惯于....24.take risks/take a risk 挑战 25.lose one’s life 失去生命26.because of 因为 27.run out of 用完28.cut off 切除29.get out of 从...出来30.make a decision/decisions 做决定31.be in control of 掌管；管理32.give up 放弃用法归纳1.need to do sth .需要去做某事2.see sb doing sth 看见某人正在做某事3.ask sb sth 询问某人某事4.expect sb to do sth 期望某人做某事5.agree to do sth 想要做某事6.help sb (to) do sth 帮助某人做某事7.want to do sth 想要做某事 8.tell sb to do sth 告诉某人做某事9.have problems(in) doing sth 做某事有困难 e sth to do sth用某物去做某事11.be/get used to doing sth 习惯于做某事 12.seem to do sth 好像做某事13.keep on doing sth 继续做某事 14.mind doing sth 介意做某事语法点1.询问某人的健康问题及遇到麻烦的表达方法2.情态动词should的用法表示劝告与建议，也表义务与责任第一人称问句中，征询建议要记清3.不定代词的用法相关阅读方法推理判断阅读法精细解读1. What’s the matter (with you)? 怎么了？出什么事了？What’s the trouble/ the problem / wrong with sb./ sth.?2. I had a cold.我感冒了。

Unit 8 Have you read Treasure Island yet?单元话题满分范文必背1．著名作家Francis曾经说过:“读书使人充实”。

阅读对我们的成长有着举足轻重的作用。

请你根据下面的信息，以“ Reading makes a full man”为题，写一篇80词左右的短文，给出你对阅读的看法和计划。

Reading makes a full man【答案】Reading makes a full manReading is very important in our life. We can get knowledge through reading. It can not only open our mind but also make us cleverer. Besides, reading is also one of the most important ways to learn a foreign language like English.Textbooks, newspapers, magazines, storybooks and other kinds of reading materials can help us know more about the outside world and help us grow into excellent persons.I’m planning to read at least two books in the ing holiday. And I’ll spend more time reading every day during my senior high school. Reading makes a full man! Let’s start reading now.【解析】【详解】1.题干解读：该题目属于命题作文，写出对阅读的看法和计划，第一段写为什么读书；第二段是读什么书；第三段是你的计划是什么。

新人教版八年级英语下册复习错题集八下·教辅易错题《新目标Unit1》试题教学提纲精品文档八下·名校教辅易错题Unit 1_试题一、单项选择1. Don’t ask your parents for money as a 20-year-old guy. Please stand on your own______.A. headB. thoughtC. opinionD. feet2. —Can you ______ the table please?—Of course, Mom!A. layB. setC. putD. Both A and B3. When the park is ______ by the storm, things start ______.A. hit, going wrongC. covered, going wrong B. hitting, to go wrongD. covering, to go wrong4. I saw some boy students ______ basketball when I ______ the playground.A. played, passedB. play, pastC. playing, passedD. to play, past5. —Did you see the accident?—Yes, the car ______ the road and hit a tree.A. run offB. run outC. run awayD. run down6. It’s easy to ______ bad habits, such as smoking.A. fall downB. fall offC. fall intoD. fall behind7. —The man did a lot of things to ______ for president(总统).—I think most of people will support him and vote for him(投他的票).A. getB. runC. fightD. catch8. Dick ______ in America, but he has been ______ Chinese food since he moved toChina.A. used to live, used to eating C. is used to live, used to eatingB. is used to live, used to eat D. used to living, used to eat9. —Could you please give me a hand? The dictionary is on the top shelf, out of myreach.—______.A. It doesn’t matterB. Not at allC. It’s my pleasureD.With pleasure10. The sun shone through a ______ in the clouds.A. breakB. restC. turnD. gap11. She is so sad. What happened ______ her?A. inB. ofC. atD. to12. The ______ boy had to stay at home by himself because both of his parents hadgone to work.A. illB. sickC. wellD. sickness13. The business failed because of ______ management.A. illB. sickC. goodD. sickness14. When your money ______, please come to me for help.A. runs out ofB. runs outC. is running out ofD. is run out15. My father didn’t expect to ______ an old friend of his when he was on vacation inParis.精品文档A. run out ofB. run afterC. run acrossD. run off16. Look! There is a pen ______ on the ground. Whose is it?A. layB. layingC. lyingD. laid17. To look for his child, he risked ______ the mountain at midnight.A. climbB. to climbC. climbedD. climbing18. How kind you are! You always do what you can ______ others.A. helpB. helpingC. helpsD. to help19. It’s necessary for the phubbers(低头族) to ______ the time they spend on their smartphones.A. cut inB. cut offC. cut down20. They cli mbed to the top of the hill ______ they could geta bird’s eye view of the city.A. in order toB. such thatC. in order thatD. as a result21. Lei Feng ______ for many years, but his spirit is still encouraging us.A. diedC. was dead B. has diedD. has been dead22.—I have ______ bad stomachache, Mr. Wang.—I’m afraid you have to get ______ X-ray.A. a; aB. a; anC. the; aD. a; the23. The park is far away from here indeed. It’s about ______ walk.A. a three hourB. a three hour’sC. a three-hoursD. a three-hour24. You shouldn’t make mistakes ______.A. in same way C. in the same wayB. at same way D. at the same way25. She has a stomachache.（同义句转换）She has ______ ______ ______.二、阅读理解填词(NEW YORK) A French tourist highly praised(赞扬) for saving a two-year-old girl in Manhattan said he didn't think twice before diving into the cold East River.Tuesday's Daily News said 29-year-old young man left the spot quickly afterb______(26) the girl to safety last Saturday.He lifted the little girl out of the water after she f______(27) off the bank(河岸) near a museum. He h______(28) the girl to her father, David Anderson, who had jumped in after him."I didn't think at all," Duret told the Daily News. "It h______(29) very fast. I reacted(反应) very fast."Duret, an engineer on vacation, was walking with his girlfriend along the bankw______(30) he saw something falling into the water. He thought it was a doll, but realized it was a child when he walked close to the river. Without thinking t______(31), he took off his coat and jumped into the water at once.When he reached the girl, she s______(32) lifeless, he said. Fortunately, when she精品文档was taken out of the water, she opened her eyes.精品文档Anderson said his d______(33) fell off the bank when he was checking his camera. An ambulance(救护车) came later for her, said Duret, who was handed clothes from onlookers(旁观者). Duret c______(34) a bus with his girlfriend shortly after.The story happened on the day before he left for France. Duret said he didn't realize his story had greatly m______(35) New York until he was leaving the next morning."I don't really think I'm a hero," said Duret. "Anyone would do the same thing."26. b________ 31. t________ 27. f________32. s________28. h________33. d________29. h________34. c________30. w________35. m________。

北师大版八年级下册易错题锦集（13）肯定与否定 定义与命题1. 把下列命题改写成“如果……那么……”的形式，并指出命题的条件和结论。

(1) 直角都相等；(2) 等角的补角相等；(3) 不相交的两条直线是平行线；(4) 同位角相等，两直线平行。

2. 若5x ＋4的平方根是±1，则x ＝__________。

3. 已知三条线段的长分别为3a ，4a ，14，如果这三条线段能构成三角形，那么a 的取值范围是__________。

4. 当x 为任意实数时，x 2＋4x ＋5的值________零（填“大于”、“小于”或“等于” ） 理由：_____________________。

5. “分数一定是实数”的条件是____________________，结论是_______________。

6. 用“”、“”定义新运算，对于任意实数a ，b 都有“a b ”＝a 和a b ＝b ，例如32＝3，32＝2，则(20072006)(20062005) ＝_____________。

7. 德国数学家莱布尼兹发现了下面的单位分数三角形（单位分数是分子为1，分母为正整数的分数）： 如下图ZM —02根据前五行的规律，可以知道第六行的数依次是_______________________。

8.如图ZM —03，已知A 1(1，0)、A 2(1，1)、A 3(－1，1)、A 4(－1，－1)、A 5(2，－1)、…。

则点A 2007的坐标是________________。

9. 甲、乙、丙、丁四人参加某校招聘教师考试，试后甲、乙两人去询问成绩。

请你根据图ZM —04，对回答的内容进行分析，则这四人的名次排列共有__________种可能。

ZM —03 ZM —02ZM —0410. 以下推理：①若y x =，则x ＝y ；②若x ≠y ，则x 2≠y 2；③若x ＝y ，则x 2＝y 2；④若x 2≠y 2，则x ≠y .正确的有___________个。

初二下学期错题档案周全福2014、2——2014、71、平行四边形ABCD的周长32, 5AB=3BC,则对角线AC的取值范围为( )A. 6<AC<10B. 6<AC<16C. 10<AC<16D. 4<AC<162、如图所示，四边形ABCD是平行四边形，按下列条件得到的四边形BFDE是平行四边形的个数是（）①图甲，DE⊥AC，BF⊥AC②图乙，DE平分∠ADC，BF平分∠ABC③图丙，E是AB的中点，F是CD的中点④图丁，E是AB上一点，EF⊥ABA。

3个B。

4个C．1个D。

2个3、如图，在□ABCD 中，DE平分∠ADC，BF平分∠ABC交AC 于E、F，求证：四边形BFDE为平行四边形。

4、如图，在□ABCD 中，EF是对角线AC的垂直平分线交AB于E，交CD于F，求证：四边形AECF是菱形。

5、将两块能完全重合的两张等腰直角三角形纸片拼成下列图形：①平行四边形（不包括菱形、矩形、正方形）②矩形③正方形④等边三角形⑤等腰直角三角形 ( ) A．①③⑤ B．②③⑤ C．①②③ D．①③④⑤6、下列说法错误的是（）A.一组对边平行且一组对角相等的四边形是平行四边形.B.每组邻边都相等的四边形是菱形.第2题图C.对角线互相垂直的平行四边形是正方形.D.四个角都相等的四边形是矩形.7、如图，以△ABC 的三边为边在BC 的同侧分别作三个等边三角形，即△ABD、 △BCE、△ACF ，请回答下列问题：（1）四边形ADEF 是什么四边形？并说明理由（2）当△ABC 满足什么条件时，四边形ADEF 是菱形？（3）当△ABC 满足什么条件时，以A 、D 、E 、F 为顶点的四边形不存在．8、如图，已知□ABCD 的对角线交点是O ，直线EF 过O 点，且平行于BC ，直线GH 过且平行于AB ，则图中能用字母表示的平行四边形共有( )个.A.10B.14C.16D.189、①若2m －4与3m －1是同一个数的平方根，则m 的值是（ ） A 、－3 B 、1 C 、－3 或1 D 、－1②若一个正数的平方根是2a －1和－a ＋2，则a ＝________③已知x 的平方根是2a ＋3和1－3a ，y 的立方根为a ，求x+y 的值. 102=，≥b ，c ≥0),那么a+b=11、①直角三角形有一条直角边长为11，另两条边长是连续的自然数，则三角形周长为 ( ) A ．130 B ．131 C ．132 D ．133 ②一个直角三角形的两边长分别为3cm 和4cm,则第三边的长为 12、如图,AB ∥CD,E,F 分别为AC,B D 的中点,若AB=5,CD=3,则EF 的长是( ) A.4 B.3 C.2 D.113、如图，已知M 是Rt△ABC 斜边AB E 。