限时训练(1)

高三物理限时训练一班别_______________ 姓名_________________ 座号____________________ 1. 下列关于速度的说法正确的是： ( )A ．速度是描述物体位置变化的物理量B ．速度方向就是物体运动的方向C ．位移方向和速度方向一定相同D ．平均速度的大小就是平均速率2．某人爬山，从山脚爬上山顶，然后又从原路返回到山脚，上山的平均速率为v 1，下山的平均速率为v 2，则往返的平均速度的大小和平均速率是( )A.v 1＋v 22， v 1＋v 22B.v 1－v 22， v 1－v 22C ．0，v 1－v 2v 1＋v 2 D ．0， 2v 1v 2v 1＋v 23．一艘船以恒定的速率，往返于上、下游两码头之间．如果以时间t 1和t 2分别表示水的流速较小和较大时船往返一次所需的时间，那么，两时间的长短关系为( )A ．t 1＝t 2B ．t 1>t 2C ．t 1<t 2D ．条件不足，不能判断4．下表是四种交通工具的速度改变情况，下列说法正确的是( )A.C ．③的速度变化最快 D ．④的末速度最大，但加速度最小 5.一个质点做运动方向不变的直线运动，加速度的方向始终与速度方向相同，但加速度的大小逐渐减小直至为零，在此过程中( )A.速度逐渐减小，当加速度减小到零时，速度达到最小B.速度逐渐增大，当加速度减小到零时，速度达到最大C.位移逐渐增大，当加速度减小到零时，位移将不再增加D.位移逐渐减小，当减速度减小到零时，位移达到最小6．一物体做匀变速直线运动，初速度为15 m/s ，方向向东，第5 s 末的速度为10m/s ，方向向西，则第几秒开始物体向西运动（ ）A ．第2sB ．第4sC ．第9sD ．第15s7． 2008年9月25日晚21点10分，我国在九泉卫星发射中心将我国自行研制的“神舟7号”宇宙飞船成功地送上太空，飞船绕地球飞行一圈时间为90分钟．则( )A ．“21点10分”和“90分钟”前者表示“时刻”后者表示“时间”B ．卫星绕地球飞行一圈，它的位移和路程都为零C ．卫星绕地球飞行一圈平均速度为零，但它在每一时刻的瞬时速度都不为零D ．地面卫星控制中心在对飞船进行飞行姿态调整时可以将飞船看作质点8.一质点做匀加速直线运动，第三秒内的位移2m，第四秒内的位移是2.5m，以下说法中正确的是（）A．这两秒内平均速度是2.25m/s B．第三秒末即时速度是2.50m/sC．质点的加速度是0.125m/s2 D．质点的加速度是0.5m/s29. 一辆汽车从原点O由静止出发沿x轴做直线运动，为研究汽车的运动而记下它的各时刻(1)(3)汽车在第4秒内的平均速度为多大？10．一辆汽车沿平直公路从甲站开往乙站，起动加速度为2m/s2，加速行驶5秒，后匀速行驶2分钟，然后刹车，滑行50m，正好到达乙站，求汽车从甲站到乙站的平均速度？解析：(1)v 2＝3m/s (2)a ＝Δv ＝4－23－1m/s 2＝1m/s 2(3)Δx 4＝3.5m ，t ＝1s ，v 4＝Δx 4t 4＝3.5m/s.解析：起动阶段行驶位移为： s 1=2121at ……（1） 匀速行驶的速度为： v = at 1 ……（2） 匀速行驶的位移为： s 2 =vt 2 ……（3） 刹车段的时间为： s 3 =32t v……（4） 汽车从甲站到乙站的平均速度为：v =s m s m s m t t t s s s /44.9/1351275/10120550120025321321==++++=++++。

限时训练(一)Ⅰ.单项填空1.Without the wise leadership of the Party，it hard to achieve the GDP growth target for 2022.A.would have beenB.would beC.wereD.had been答案 B解析考查虚拟语气。

句意为：要是没有党的英明领导，很难实现2022年国内生产总值增长的目标。

此处without短语相当于虚拟条件句，根据题干中的“2022”判断是对将来的虚拟，主句用would＋do的形式，故B项正确。

2.Parents’top priority is to help their kids develop the ability to show in their choices of friends.binationB.admirationC.inspirationD.discrimination答案 D解析考查名词词义辨析。

combination结合；admiration钦佩；inspiration灵感；discrimination 区别，识别。

句意为：父母的首要任务是帮助他们的孩子发展在选择朋友时的识别能力。

根据句意可知D项正确。

3.As Emerson puts it，we travel the world over to find the beautiful，we must carry it with us or we find it not.A.unlessB.untilC.thoughD.because答案 C解析考查连词词义辨析。

句意为：如爱默生所言，我们环游世界是为了寻找美，但是我们必须与美同行才能发现它。

unless除非；until直到；though尽管；because因为。

根据句意可知，这里表示一种让步关系，故选C。

4.I felt like giving up.I probably ，but my Dad whispered，“Come on! You can make it.”A.would haveB.wouldC.shouldD.should have答案 A解析考查过去将来时。

直线运动限时训练1一、单选13. (2010年海南卷)下列说法正确的是()A．若物体运动速率始终不变，则物体所受合力一定为零B．若物体的加速度均匀增加，则物体做匀加速直线运动C．若物体所受合力与其速度方向相反，则物体做匀减速直线运动D．若物体在任意的相等时间间隔内位移相等，则物体做匀速直线运动14.（2011年重庆）某人估测一竖直枯井深度，从井口静止释放一石头并开始计时，经2s听到石头落地声，由此可知井深约为（不计声音传播时间，重力加速度g取10m/s2）A.10mB. 20mC. 30mD. 40m15. （2013年广东）某航母跑道长200m.飞机在航母上滑行的最大加速度为6m/s2，起飞需要的最低速度为50m/s.那么，飞机在滑行前，需要借助弹射系统获得的最小初速度为A.5m/sB.10m/sC.15m/sD.20m/s16.（2011年天津）质点做直线运动的位移x与时间t的关系为x = 5t + t2（各物理量均采用国际单位制单位），则该质点A．第1s内的位移是5m B．前2s内的平均速度是6m/sC．任意相邻1s内的位移差都是1m D．任意1s内的速度增量都是2m/s二、双选17．在同一地点，甲、乙两个物体沿同一方向作直线运动的速度一时间图象如图所示，则A．两物体相遇的时间是2S和6SB．乙物体先在前运动2S，随后作向后运动C．两个物体相距最远的时刻是1S末和4S末D．4s-6s内乙在甲前面18．甲、乙两车某时刻由同一地点沿同一方向开始做直线运动，若以该时刻作为计时起点，得到两车的x－t图象如图所示，则下列说法正确的是A．t1时刻乙车从后面追上甲车B．t1时刻两车相距最远C．t1时刻两车的速度刚好相等D．0到t1时间内，乙车的平均速度等于甲车的平均速度19．甲、乙两物体的v －t 图象如图所示，则A.甲、乙两物体都做匀速直线运动B.甲、乙两物体若在同一直线上，就一定会相遇C.甲的速率大于乙的速率D ．甲、乙两物体若在同一直线上，就一定不会相遇20．在防恐军事演习中，某空降兵从飞机上跳下，先做自由落体运动，在t 1时刻，速度达到较大值v 1时打开降落伞，做减速运动，在t 2时刻以较小速度v 2着地，他的速度图象如图所示．下列说法正确的是A.在0～t 1内，该空降兵的平均速度v ＝v 12B.在t 1～t 2内，该空降兵的平均速度v ＝v 1＋v 22C ．在t 1～t 2内，该空降兵的平均速度v ＞v 1＋v 22D ．在t 1～t 2内，该空降兵的平均速度v ＜v 1＋v 2221．如图所示(t 轴单位为s)，有一质点，当t ＝0时从原点由静止开始出发，沿直线运动，则A ．t ＝0.5 s 时离原点最远B ．t ＝1 s 时离原点最远C ．t ＝1 s 时回到原点D ．t ＝2 s 时回到原点（2010年广东高考）（1）图13是某同学在做匀变速直线运动实验中获得的一条纸带。

限时训练(一)字音(第二课时)1．下列词语中加点的字，每对读音完全相同的一组是( )A．.笼．罩／笼．络弄．堂／舞丈弄．墨答．谢／一问一答．B．慰藉．／狼藉．收拾．／拾．级而上渐．染／东渐．于海C．丧．礼／丧．胆兴．奋／夙兴．夜寐悄．寂／悄．声细语D．泥．墙／拘泥．散．布／烟消云散．省．亲／不省．人事答案：D答题指要：泥(nì)，散(sàn)，省(xǐng)。

A．弄(lîng)堂／舞文弄(nîng)墨；B．慰藉(jiâ)／狼藉(jí)，收拾(shí)／拾(shâ)级而上；C．丧(sāng)礼／丧(sàng)胆。

2．下列各组词语中加点的字是多音字，其中有两种读音的一组是（）A．宁．愿宁．缺毋滥宁．死不屈宁．折不弯宁．为玉碎B．间．谍挑拨离间．亲密无间．黑白相间．间．接经验C．匀称．称．心如意称．孤道寡啧啧称．奇拍手称．快D．面相．相．机行事相．貌堂堂吉人天相．相．时而动答案：C答题指要：C “称心如意”“匀称”中的“称”读chân，其它读chēng；A、n ìng；B、jiàn； D、xiàng。

3．下列词语中加点的字，每对的读音完全相同的一组是（）A．徇．私/驯．熟咆哮．/肖．像惬．意/提挈．连咳．带喘/金蝉脱壳．B．偈．语/鲫．鱼畏葸．/玉玺．胴．体/栋．梁耆．年硕德/骐．骥一跃C．投奔．/奔．命着．急/着．火给．养/给．以强．词夺理/强．人所难D．丧．气/沮丧．殷．实/殷．红反省．/省．悟罪不当．罚/独当．一面答案：B答题指要：A、“徇”、“驯”读xùn；“哮”、“肖”读xiāo；“惬”、“挈”读qiâ；“咳”读kã；“壳”读qiào。

B、“偈”、“鲫”读jì；“葸”、“玺”读xǐ；“胴”、“栋”读dîng；“耆”、“骐”读qí；C、“奔”读bân；“给”分别jǐ、gěi；“着”读zháo；“强”读qiǎng。

)E Al)( )DL B T C Mx)A. (2 , 3) B5 •把不等式组8已知关于 该抛物线上的是（ B10 .如图 X 1 - 7 A. 4 B . 6 C . 8 D . 10(0 , 3) C . ( -1 , 3) D . ( -3, 3)图 X 1- 4匀速运动，终点为 C,过运动路线上任意一点 P 作PMLx 轴于M PNLy 轴于N,设四边形OMP 的面积为S, P 点运动的时间为 于t 的函数图象大致是B图 X 1-6图 X 1- 5( )则AE 的长为（( )图 X 1- 7正方形ABCD 勺边长为6,点E,7.如图X 1-4，在?ABC ［中，用直尺和圆规作/ BAD 勺平分线AG 交BC 于点E 若BF = 6, AB= 5A. 10 B . 3 C . 4 D . 5t ，则S 关-io-i B 图 X 1-3A. 0 B . 1 C. .2 D . 2 x> — 1 ,的解表示在数轴上，下列选项正确的是x + 2<36•在Rt △ ABC 中，两直角边的长分别为 6和8,则其斜边上的中线长为 A. 2 ,10 B . 3k9•如图X 1 -5,已知AB 是反比例函数y = x （k >0,x >0）图象上的两点，BC" x 轴，交y 轴于点C 动点P 从坐标原点0出发，沿 x 的方程ax + b = 0（a ^0）的解为x =- 2,点（1 , 3）是抛物线y =ax 2 + bx + c （a ^0）上的一个点，则下列四个点中一定在）6590000人次.将6590000用科学 D . 6.59 X 10 65 C. | ■ 10 D. 10 52. 如图X 1- 1，下面几何体的俯视图是（3. 据统计，2015年广州地铁日均客运量约为 记数法表示为（ ）A . 6.59 X 104 B . 659 X 1044•已知一组数据0，— 1, 1 , 2, 3，则这组数据的方差为（ A.2 B . - 2 C . 2 D . - 1C . 65.9 X 105 F 分另U 在AB AD 上，若CE= 3砺，且/ EC = 45°, _则CF 的长为（选择填空限时训练（一）（限时30分钟 满分54分） -、选择题（本题共10小题，每小题3分，共30分）1 .-2的相反数是（）二、填空题（本题有6小题，每小题4分，共24分）11 •请写出一个解为x= 1的一元一次方程： ________12 .如图X1 - 8是一个斜体的“土”字，AB// CD已知/ 1 = 75°,则/2= ____________图X1- 813 •为了了解某毕业班学生的睡眠时间情况，小红随机调查了该班15名同学，结果如下表:每天睡眠时间（单位：小时）77.588.59人数24531则这1514. 如图X1 -9,将弧长为6 n的扇形纸片AOB S成圆锥形纸帽，使扇形的两条半径0A与0B重合（粘连部分忽略不计），则圆锥形纸帽的底面圆半径是 _________ .a b15. 如图X1 -10,已知点B D在反比例函数y=-（a>0）的图象上，点A, C在反比例函数y = -（b<0）的图象上，AB// CD// x轴，ABX —AB= 4, CD= 3, AB与CD间的距离为1，贝U a- b的值是 ______16. _______________________________________________________________________________ 如图X1 - 11，点A（2 , 0），以0A为半径在第一象限内作圆弧AB使/ A0= 60°,点C为弧AB的中点，D为半径0A上一动点（不与点0 A重合），点A关于直线CD的对称点为E若点E落在半径0A上,则点E的坐标为______________________________________________________________ ;若点E落在半径0B上，则点E的坐标为_________ .计算：1| 3-2| + 20170-( -3) -1+ 3tan30 ° +8.CD在—轴的同侧,图X1- 10参考答案1. C 2.A 3.D 4.D 5.B6. D7.C8.D9.B 10.A11.x - 1 = 0(答案不唯一)12.10513. 8 8 14.3 15.1216. (2 3 - 2, 0) (.3 - 1, 3 - 3)加加练解：原式=2- .3+ 1 -( -3) +3X。

地理限时训练（一）【建议时间15分钟】
使用日期：选题：张毅老师批阅人：得分：姓名： 1.
读“地质构造示意图”，完成下列问题。

（14分）
（1）从地质构造上看属于向斜的字母是，属于地堑的字母是。

（2）出现图中“背斜成谷，向斜成山”这一地形倒置现象是受到（内力/外力）作用；
关于这一现象叙述正确的是。

（双选）
①向斜槽部受挤压力的作用岩层坚实不易侵蚀形成的山地
②背斜槽部受挤压力的作用岩层坚实不易侵蚀形成的谷地
③向斜顶部受张力的作用岩层脆弱受外力侵蚀形成的山地
④背斜顶部受张力的作用岩层脆弱受外力侵蚀形成的谷地
（3）若开采地下水，最好在处；若为开采方便，采石场最好选择处（填字母）。

2.读六大板块示意图，完成下列问题。

（16分）
（1）图中表示美洲板块的是（序号）；⑥表示的板块名称是（名称）；
（2）日本群岛是_____板块（序号）和_____板块（序号）（张裂/挤压）形成的，其位于板块的______（生长/消亡）边界附近，地壳较为活跃，故其多、等地质灾害。

注：本次测验选自于2014年重庆一中高2017级高一上期第三次定时练习（2014.12）背诵要点收获：
地理限时训练（一）【参考答案】
1.
2.(每空2分，共16分)
(1) ______⑤__ ____，南极洲板块。

(2) _______①______，_____②________，_____挤压______，
_____消亡__ ___，_____火山______，_____地震______
（注：第2小题：1和2、5和6答题顺序可互换）。

江苏省常州市金沙高级中学2021届高三下学期限时训练（一）英语试题第一部分：阅读理解（共两节，满分30分）第一节（共7个小题：每小题2.5分，满分17.5分）AWhat do the random, scribbled(潦草的)drawings crowding the margins(页边空白)of most high school students’ papers mean? When a student is caught doodling(乱画)in class, he will probably be criticized for daydreaming. But doodling while listening can help with remembering details, rather than implying that the mind is wandering, according to a study published in the scientific journal Applied Cognitive Psychology.In an experiment conducted by the Medical Research Council’s Cognition and Brain Sciences Unit in Cambridge,40 subjects were asked to listen to a two-minute tape giving several names of people and places. Half of the participants were asked to shade in shapes on a piece of paper at the same time, without paying attention to neatness, while the rest were given no such instructions. After the tape had finished, all participants in the study were asked to recall the names of people and places. The doodlers recalled on average 7.5 names of people and places, compared to only 5.8 by the non-doodlers.“If someone is doing a boring task, like listening to a dull telephone conversation, they may start to daydream.” said study researcher, Professor Jackie Andrade, of the School of P sychology, University of Plymouth. “Daydreaming distracts them from the task, resulting in poorer performance. A simple task, like doodling, may be enough to stop daydreaming without affecting performance on the main task.”“In psychology, tests of memory or attention will often use a second task to selectively block a particular mental process. If that process is important for the main task, then performance will be weakened. But my research suggests that in everyday life doodling may be something we do because it helps to keep us on track with a boring task, rather than being an unnecessary distraction(分心)that we should try to resist doing.” said Andrade.Dan Ware, a social study teacher, used to consider doodling a distraction from learning, butafter teaching kids with all personality types he learned scribbling away during lectures helps certain students remember more information. “In my first few years of teaching, I thought, ‘Well, this kid isn’t paying attention. He’s daydreaming.’ But I had some real ly powerful experiences with students and came to understand in many cases that was their way of focusing, and those students were probably paying more attention than other students.” Ware said.1. What do we know about the participants involved in the experiment?A. Some were asked to note down the information neatly.B. Some were asked to memorize the names they would hear.C. Some were instructed to listen to the tape with full attention.D. Some were instructed to make random drawings on paper.2. Which of the following will both Jackie Andrade and Dan Ware agree with?A. Doodling helps some people focus.B. Doodling makes a dull task interesting.C. Students who doodle perform poorly.D. Students who doodle lack concentration.3. What is the best title of the text?A. Daydreaming Can Sharpen Study SkillsB. Doodling Can Help Memory RecallC. A Wandering Mind Improves ProductivityD. Distractions Harm Academic PerformanceBShyness is the cause of much unhappiness for a great many people. Shy people are anxious and self-conscious; that is, they are concerned about their own appearance and actions too much. Negative thoughts are constantly occurring in their minds: What kind of impression am I making? Do they like me? Do I sound stupid? Am I wearing unattractive clothes?It is obvious that such uncomfortable feelings must affect people unfavorably. A person’s self-concept is reflected in the way he or she behaves and the way a person behaves affects other people’s reactions. In general, the way p eople think about themselves has a deep effect on all areas of their lives.Shy people, who have low respect, are likely to be passive and easily influenced by others. They need faith that they are doing ＂the right thing＂. Shy people are very sensitive to criticism. It makes them feel inferior(自卑). They also find it difficult to be pleased by praises because they believe they are unworthy of praise. A shy person may respond to a praise with a statement like this one: ＂You’re just saying that to make me feel good. I know it’s not true.＂It is clear that,. while self-awareness is a healthy quality, overdoing it is harmful.Can shyness be completely got rid of, or at least reduced? Fortunately, people can overcomeshyness with determination since shyness goes hand in hand with lack of self-respect. It isimportant for people to accept their weaknesses as well as their strengths. Each one of us has hisor her own characteristics. We are interested in our own personal ways. The better we understandourselves, the easier it becomes to live up to our chances for a rich and successful life.4. The first paragraph is mainly about ____________.A. the cause of shynessB. the effect of shyness on peopleC. the feelings of shy peopleD. the questions in the minds of shy people5. According to the writer, self-awareness is ____________.A. harmful to peopleB. a weak point of peopleC. the cause of unhappinessD. a good characteristic6. What is the shy people’s reaction to praise?A. They are pleased by it. B They feel it is not true.C. They are very sensitive to it.D. They feel they are worthy of it.7. We can learn from the passage that shyness ____________.A. blocks our chances for a successful lifeB. helps us to live up to our full developmentC. enables us to understand ourselves betterD. has nothing to do with lack of self-respect第二节（共5小题，每小题2.5分，满分12.5分）根据短文内容，从短文后的选项中选出能填入空白处的最佳选项，选项中有两项为多余选项。

高一语文第一次限时训练一、客观题1．下列词语中加点字的读音，完全正确的一项是（）A．彷（páng）徨青荇（xìng）遒劲（jìn）颓圮（qǐ）B．长篙（gāo）漫溯（sù）青苔（tāi）火钵（bō）C．愤懑（mǎn）冰屑（xuè）麦糟（zāo）叱（chì）骂D．袒露（lù）隽（juàn）永碣（jié）石忸怩（ní）2．下列词语中，没有错别字的一组是（）A．凄婉漂泊褒扬击浊扬清B．斑斓笙萧抨击剑拔驽张C．榆阴气概瓦菲意气风发D．讴歌扭扣寥廓天伦之乐3．下列句子中，成语使用恰当的一句是（）A．袁弘表示，世上没有天生或是一蹴而就的坏人，自己会在饰演的这一版本的杨康中加深刻画其心理变化的过程，将其内心的迷茫和矛盾展现出来。

B．中日双方首脑同时以更加明确清晰的语言表示，解决东海共同开发问题倚马可待，现在剩下的可能就是技术层面或者事务层面的问题了。

C．日本捕鲸者不顾国际社会谴责，把非法捕捉到的鲸鱼屠宰、清洗、销售，以牟取暴利，血腥的一幕令人惨不忍睹。

D．房地产市场对宏观调控“免疫”，更深层的原因是市场制度存在重大的制度缺陷，若不从制度改革入手釜底抽薪，恐怕再多的“组合拳”和“重拳”都难以“拳拳到肉”。

4．下列各句中，没有语病的一句是（）A．由于这种思想上的局限性，使得韩愈的文体改革运动仅仅以模仿先秦诸子的散文为目标，而不能像先秦诸子和司马迁那样以接近人民口语为目标来创造新的散文。

B．这种如鱼得水似的悠闲，让后世的学者在感叹中国人融入西方社会的艰难时，不得不叹服徐志摩是“最适应西方生活的中国文人”。

C．在这一时期，毛泽东同志在长沙组织了湖南学生联合会、新民学会，开办了平民夜校、文化书社和湖南自修大学，参加了反对袁世凯称帝，领导了驱逐张敬尧等军阀。

D．行政处罚在程序上的公正、合理与否，将直接影响行政处罚的内容的有效和成立。

高三英语晚自习限时训练【3月31日晚限制：不超过65-70分钟】一、六选四阅读1. Complete the following passage by using the sentences given below. Each sentences can be used only once. Note that there are two more sentences than you need.Can just one person make a difference? You bet! In a community every person counts, and getting involved is not difficult. Take stock of your own talents and interests. Don't wait for someone else to act first. Take the initiative! Once you see what you can accomplish, you'll want to keep going.Here are just a few ways to make a difference in your community. How many more ways can you come up with?Clean up the community. People often throw litter in places where there is already litter. And the problem only becomes worse until someone gets fed up and does something. Could your neighborhood use a cleanup? Neighborhood cleanups are often sponsored by local businesses or schools. But if your community doesn't have a cleanup program, get together with friends to organize one. You could pick up garbage in a larger area twice a year, or you could clean a smaller area every few months.Include the isolated. Do you know anyone who is housebound? Almost all neighborhoods have a few people who have to stay at their homes. These people are often elderly and unable to leave their homes to perform simple tasks. By letting them "borrow" your legs and eyes, you can make them feel included. You can run errands for them like shopping or paying bills. They might like you to read to them if their eyesight is failing. Governments provide some of the services these people need, but programs cannot give them friendship; that's what communities are for!Reading clubs are popular all over Europe and North America. Members might read at home to prepare for discussion, or they might read aloud to each other and talk about what they just read. Either way, a book or article can spark lively discussion and this often challenges people to take action.A. Cleaning your community will have a positive effect on others in society.B. They find a need or an issue you really care about.C. But they belong to the community, too.D. Living in a clean neighborhood will be its own reward.E. Don't hesitate to take part in the community's activity.F. Round up some readers.二、语法填空阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

高二物理（创）周考练一、选择题（1、4、10、11、12多选，其他单选）1．下列说法中正确的是()．A．每种金属都有确定的电阻率，电阻率不随温度变化B．导线越细越长，其电阻率也越大C．一般金属的电阻率，都随温度升高而增大D．测电阻率时，为了提高精度，通过导线的电流要足够大，而且要等到稳定一段时间后才可读数2.电位器是变阻器的一种．如图所示，如果把电位器与灯泡串联起来，利用它改变灯的亮度，下列说法正确的是()．A．连接A、B使滑动触头顺时针转动，灯泡变暗B．连接A、C使滑动触头逆时针转动，灯泡变亮C．连接A、C使滑动触头顺时针转动，灯泡变暗D．连接B、C使滑动触头顺时针转动，灯泡变亮3．如图所示是电阻R1和R2的伏安特性曲线，并且把第一象限分为Ⅰ、Ⅱ、Ⅲ三个区域，现在把R1和R2并联在电路中，消耗的电功率分别为P1和P2，并联总电阻设为R.下列关于P1和P2的大小关系及R的伏安特性曲线应该在的区域正确的是()．A．特性曲线在Ⅰ区，P1<P2B．特性曲线在Ⅲ区，P1>P2C．特性曲线在Ⅰ区，P1>P2D．特性曲线在Ⅲ区，P1<P24．某导体中的电流随其两端电压的变化如图7-1-9所示，则下列说法中正确的是()．A．加5 V电压时，导体的电阻约是5 ΩB．加12 V电压时，导体的电阻约是1.4 ΩC．由图可知，随着电压的增大，导体的电阻不断减小D．由图可知，随着电压的减小，导体的电阻不断减小5．两个电阻，R1＝8 Ω，R2＝2 Ω，并联在电路中，欲使这两个电阻消耗的电功率相等，可行的办法是()．A．用一个阻值为2 Ω的电阻与R2串联B．用一个阻值为1 Ω的电阻与R2串联C．用一个阻值为6 Ω的电阻与R1串联D．用一个阻值为2 Ω的电阻与R1串联6.甲、乙两根保险丝均为同种材料制成，直径分别是d1＝0.5 mm和d2＝1 mm，熔断电流分别为2.0 A和6.0 A，把以上两根保险丝各取等长一段并联后再接入电路中，允许通过的最大电流是().A.6.0 A B．7.5 AC.10.0 A D．8.0 A7．如图所示，电源电动势E＝8 V，内电阻为r＝0.5 Ω，“3 V，3 W”的灯泡L与电动机M串联接在电源上，灯泡刚好正常发光，电动机刚好正常工作，电动机的线圈电阻R0＝1.5 Ω.下列说法中正确的是()．A．通过电动机的电流为1.6 AB．电源的输出功率是8 WC．电动机消耗的电功率为3 WD．电动机的输出功率为3 W8．两根材料相同的均匀导线x和y串联在电路中，两导线沿长度方向的电势变化情况分别如图中的ab段和bc段图线所示，则导线x和y的横截面积之比为()．A．2∶1 B．1∶2C．6∶1 D．1∶69．在如图所示的电路中，E为电源，其内阻为r，L为小灯泡(其灯丝电阻可视为不变)，R1、R2为定值电阻，R3为光敏电阻，其阻值大小随所受照射光强度的增大而减小，V为理想电压表．若将照射R3的光的强度减弱，则()．A．电压表的示数变大B．小灯泡消耗的功率变小C．通过R2的电流变小D．电源内阻消耗的电压变大10．如图所示，电源电动势为E，内阻为r，不计电压表和电流表内阻对电路的影响，当电键闭合后，两小灯泡均能发光．在将滑动变阻器的触片逐渐向右滑动的过程中，下列说法正确的是()．A．小灯泡L1、L2均变暗B．小灯泡L1变亮，小灯泡L2变暗C．电流表A的读数变小，电压表V的读数变大D．电流表A的读数变大，电压表V的读数变小11．如图所示，电源电动势为E，内电阻为r，两电表均可看做是理想电表．闭合开关，使滑动变阻器的滑片由右端向左滑动，在此过程中()．A．小灯泡L1、L2均变暗B．小灯泡L1变暗，L2变亮C．电流表A的读数变小，电压表V的读数变大D．电流表A的读数变大，电压表V的读数变小12、如图所示电路中，电源内阻不能忽略，两个电压表均为理想电表．当滑动变阻器R 2的滑动触头P 滑动时，关于两个电压表V 1与V 2的示数，下列判断正确的是( )．A ．P 向a 滑动V 1示数增大、V 2的示数减小B ．P 向b 滑动V 1示数增大、V 2的示数减小C ．P 向a 滑动，V 1示数改变量的绝对值小于V 2示数改变时的绝对值D ．P 向b 滑动，V 1示数改变量的绝对值大于V 2示数改变量的绝对值二、解答题13．两个分别用长l = 5cm 的绝缘细线悬挂于同一点的相同金属小球（可视为点电荷），带有等量同种电荷。