北邮802电子电路2014真题
北京邮电大学 模拟电路实验
矿石收音机论坛?〓基础知识普及〓?面包板及其使用法 面包板及其使用法 面包板及其使用法 编者注：为了提高青少年的电子技术素养，促进学生全面发展，培养创业意识和创造技能，本刊（无线电）特约多年从事科普教育的特级教师，北京市有特殊贡献的专家孙心若撰写“电子控制技术入门”系列文章。他根据丰富的电子技术、发明创造教学体验，结合青少年的身心特点，进行有趣的“做中学”和“学中做”电路实验，引导青少年由表及里、由浅入深、循序渐进，获得“操作”体验，熏陶科学情感、发展技术能力，特别提供电子技术发展信息，增强创新意识并为他们展示创造能力营造条件。在内容选择上以电子控制技术内容为中心，以基本电路实验为基础，以数字集成电路为重点，并涉及实验所必需的基本理论及技能技巧，同时介绍青少年感兴趣的一些电子器件、小制作和小发明实例。配刊光盘中将用活动图像的形式讲解和演示这些电路实验的过程和现象，光盘中还加入了一些生活中的应用实例。 一、什么是＂面包板＂？ 1.面包板的构造 面包板即＂集成电路实验板＂，就是一种插件板，此＂板＂上具有若干小型＂插座（孔）＂．在进行电路实验时，可以根据电路连接要求，在相应孔内插入电子元器件的引脚以及导线等，使其与孔内弹性接触簧片接触，由此连接成所需的实验电路。图1为SYB—118型面包板示意图： 为4行59列，每条金属簧片上有5个插孔，因此插入这5个孔内的导线就被金属簧片连接在一起。簧片之间在电气上彼此绝缘。插孔间及簧片间的距离均与双列直插式（DIP）集成电路管脚的标准间距2.54mm相同，因而适于插入各种数字集成电路。 2.面包板使用注意事项 插入面包板上孔内引脚或导线铜芯直径为0.4～0.6mm，即比大头针的直径略微细一点。元器件引脚或导线头要沿面包板的板面垂直方向插入方孔，应能感觉到有轻微、均匀的摩擦阻力，在面包板倒置时，元器件应能被簧片夹住而不脱落。面包板应该在通风、干燥处存放，特别要避免被电池漏出的电解液所腐蚀。要保持面包板清洁，焊接过的元器件不要插在面包板上。 3.面包板实验套材
2014年公共英语三级考试试题(三)
公共英语三级考试试题(三) 一、Section Ⅱ Use of English（共20小题,共20.0分）Read the following text． Choose the best word or phrase for each numbered blank and mark A, B, Cot Don ANSWER SHEET 1． 第1题 Most young people enjoy some form of physical activity. It may be walking, cycling or swimming, in winter, or skating or skiing. It may be a game of some kind — football, hockey, golf or tennis. It may be mountaineering. These who have a passion (1) climbing high and difficult mountains are often (2) with astonishment. Why are men and women (3) to suffer cold and hardship, and to (4) on high mountains? This astonishment is caused, probably, by the difference between mountaineering and other forms of activity (5) which men give their leisure. Mountaineering is a sport and not a game. There are no man-made roles, as there are for (6) games as golf and football. There are, of course, rules of different kinds which it would be dangerous to (7) ,but it is this freedom from man-made rules (8) makes mountaineering attractive to many people. Those who climb mountains are free to use their own (9) . If we (10) mountaineering with other more familiar sports, we might think that one big difference is (11) mountaineering is not a" team work". We should be mistaken in this. There are, it is true, no "matches" (12) "teams" of climbers, but when climbers are on a rock face linked by a rope on which their lives may (13) ,there is obviously teamwork. A mountain climber knows that he may have to fight forces that are stronger and more powerful than man. He has to fight (14) of nature. His sport requires high mental and (15) qualities. A mountain climber (16) to improve in skill year after year. A skier is probably past his best by the age of thirty, and most international tennis champions (17) in their early twenties. But it is not (18) for men of fifty or sixty to climb the highest mountains in the Alps. They may take more (19) than younger men, but they probably climb with more skill and less (20) of effort, and they certainly experience equal enjoyment. A physician B physical
2018_2019学年第一学期《电子电路基础》理论考试期末试卷
2018~2019学年第一学期《电子电路基础》理论考试期末试卷（机电专业） 一、填空题（每空1分，共 30 分） 1、稳压二极管工作于区，在稳压电路中，必须串接电阻，防止超过极限值而发生热击穿损坏稳压管。 2、三极管有两个结，分别为、，三个电极分别为、和和三极管按内部结构不同可分为和型。 3、三极管的输出特性曲线可分为三个区域，即区、区和区，当三极管工作在区时，Ic=βIb 4、为了使放大器不失真地放大信号，放大器必须设置适当的，以保证三极管始终工作在区。 5、在共射基本放大器中（NPN管），若静态工作点设置偏高，易产生失真，减小饱和失真的方法是使Rb ,Q点下移；静态工作点设置偏低，易引起失真，此时，ic的半周出现平顶，uce的半周出现平顶。 6、多级放大器的级间耦合方式有、、和等四种。 7、按反馈的极性分，有反馈和反馈，判断方法可采用，反馈结果使净输入量减小的是反馈，使净输入量增大的是反馈。 二、判断题（每空2分共20分） 1、晶体二极管的正向特性也有稳压作用。（） 2、稳压二极管按材料分为硅管和锗管。（） 3、二极管的反向电阻越大，其单向导电性能就越好。（） 4、晶体二极管和三极管都是非线性器件。（） 5、放大器能放大信号的能量来源于电源Vcc。（） 6、共射放大器产生截止失真的原因，是它的静态工作点设置偏低。（） 7、射极输出器电压放大倍数小于1，接近于1，所以射极输出器不是放大器。（） 8、共基极放大器没有电流放大作用，所以没有功率放大能力。（） 9、直流放大器的级间耦合，可采用变压器耦合。（） 10、在串联反馈中，反馈信号在输入端是以电压形式出现，在并联反馈中，反馈信号在输入端是以电流形式出现。（） 三、选择题（每空2分共40分） 1、测量小功率晶体二极管性能好坏时，应把万用表欧姆挡拨到（）。 A.R×100或R×1K B.R×1 C.R×10K 2、半导体中的空穴和自由电子数目相等，这样的半导体称为（）。 A.P型半导体 B.本征半导体 C.N型半导体3、二极管的正向电阻（）反向电阻。 A.大于 B.小于 C.等于 D.不确定 4、三极管的发射结正偏，集电结反偏时，三极管处于（）。 A.放大状态 B.饱和状态 C.截止状态 5、三极管在饱和状态时，它的Ic将（） A.随Ib的增加而增加 B.随Ib的增加而减小 C.与Ib无关 6、三极管的特性曲线是指它的（） A.输入特性曲线 B.输出特性曲线 C.输入特性和输出特性曲线 7、在三极管的输出特性曲线中，每一条曲线与（）对应。 A.输入电压 B.基极电压 C.基极电流 8、在三极管放大器中，三极管各极电位最高的是（）。 A.NPN管的集电极 B.PNP管的集电极 C.NPN管的发射极 D.PNP管的基极 9、三极管组成放大器时，根据公共端的不同，可有（）种连接方式。 A.1 B.2 C.3 D.4 10、电压放大器的空载是指（）。 A.Rc=0 B.RL=0 C.RL=∞ D.Rc=∞ 11、放大器的交流通路是指（）。 A.电压回路 B.电流回路 C.交流信号流过的路径 12、放大器与负载之间要做到阻抗匹配，应采用（）耦合。 A.阻容 B.变压器 C.直接 13、直接耦合放大器（）。 A.只能传递直流信号 B.只能传递交流信号 C.交直流信号都能传递 14、阻容耦合放大器（）。 A.只能传递直流信号 B.只能传递交流信号 C.交直流信号都能传递 15、采用差分放大器的目的是为（）。 A.抑制零点漂移 B.提高电压放大倍数 C.增大输入电阻 16、反馈放大电路的含义是（）。 A.输入与输出之间有信号通路 B.电路中存在反向传输的信号通路 C.除放大电路外，还有反向传输的信号通路。 17、如图所示，反馈类型为（）。
2014年9月公共英语三级考试真题及答案
2014年9月公共英语三级考试真题及答案SECTION I Listening Comprehension (略) SECTION Ⅱ Use of English ( 15 minutes) Directions: Read the following text. Choose the best word or phrase for each numbered blank and mark A, B,C, or D on your ANSWER SHEET. Folk toys are those whose designs have passed down through the generations, made by hand and not in factories. 26 manufactured toys, they are not protected by copyrights or patents, 27 have they been standardized by machine production. Early folk toys were made of natural materials 28 wood, cloth, metal, earth, and 29 found materials. Wood was often used 30 it was available, easily worked, and required no painting. Toys were considered unimportant, so 31 was written about them. A parent made toys for a child, or children themselves made toys. The toys often were 32 made and used action movements. Traditionally, fathers and boys have been most interested in 33 toys, while mothers and girls have 34 dolls and needlework. Folk toys include action toys, models, games, puzzles, and dolls. This basic 35 can be enlarged to include skill toys, balance toys, flying toys, shooting toys, _ 36 incorporating music or noise, and animated toys. The 37 name is lost in history, and the descriptive names given to the toys 38 . Typical names include Bullroarer, Jacob' s Ladder, and Limber Jack. Early settlers of the Appalachian region mostly came from Germany, England, Scotland, andIreland, 39 knowledge of folk toys from their home countries. The designs often were 40 in the process of handing them 41 , so now there are many variations. The making of homemade toys decreased in 42 of prosperity, when people could 43 manufactured toys. Recently there is a new 44 for the mountain folk toy heritage, 45 And handcrafted toys are sometimes bought in preference to manufactured toys. 26. [ A ] Without [ B ] Unlike [ C ] Despite [ D ] Besides 27. [A] so [B] or [C] nor [D] as
北邮英语练习
一、完形填空（共1道小题，共50.0分） 1.Once, three fishes lived in a pond. One evening, some ___1___ passed by the pond and saw the fishes. “This pond is full of fish”, they told each other __2___. “We have never fished here before. We must come back tomorrow morning with our ___3___ and catch these fish!” So saying, the fishermen left. When the eldest of the three fishes ___4___ this, he was troubled. He called the other fishes together and said, “Did you hear ___5___ the fishermen said? We must leave this pond at once. The fishermen will return tomorrow and kill us all!” The second of the three fishes agreed. “You are right”, he said. “We must leave the pond.” But the ____6___ fish laughed. “You are worrying without reason”, he said. “We have lived in this pond all our lives, and no fisherman has ever come here. Why should these men return? I am not going ___7____ - my luck will keep me safe.” The eldest of the fishes left the pond that ___8____ evening with his entire family. The second fish saw the fishermen ____9___ in the distance early next morning and left the pond at once with all his family. The third fish refused to leave even then. The fishermen ____10___and caught all the fish left in the pond. The third fish's luck did not help him - he too was caught and killed. (232字) a. A.fishersman B.fisherman C.fishermans D.fishermen 学生答案: D; 标准答 案: D b. A.excitedly B.excited C.excite
北邮通电实验报告
实验3 集成乘法器幅度调制电路 信息与通信工程学院 2016211112班 苏晓玥杨宇宁 2016210349 2016210350
一．实验目的 1．通过实验了解振幅调制的工作原理。 2．掌握用MC1496来实现AM和DSB的方法，并研究已调波与调制信号，载波之间的关系。3．掌握用示波器测量调幅系数的方法。 二．实验准备 1．本实验时应具备的知识点 （1）幅度调制 （2）用模拟乘法器实现幅度调制 （3）MC1496四象限模拟相乘器 2．本实验时所用到的仪器 （1）③号实验板《调幅与功率放大器电路》 （2）示波器 （3）万用表 （4）直流稳压电源 （5）高频信号源 三．实验内容 1．模拟相乘调幅器的输入失调电压调节。 2．用示波器观察正常调幅波（AM）波形，并测量其调幅系数。 3．用示波器观察平衡调幅波（抑制载波的双边带波形DSB）波形。 四．实验波形记录、说明 1.DSB信号波形观察
2.DSB信号反相点观察 3.DSB信号波形与载波波形的相位比较 结论：在调制信号正半周期间，两者同相；负半周期间，两者反相。
4.AM正常波形观测 5.过调制时的AM波形观察（1）调制度为100%
（2）调制度大于100% （3）调制度为30% A=260.0mv B=140.0mv
五．实验结论 我们通过实验了解振幅调制的工作原理是：调幅调制就是用低频调制信号去控制高频振荡（载波）的幅度，使其成为带有低频信息的调幅波。目前由于集成电路的发展，集成模拟相乘器得到广泛的应用，为此本实验采用价格较低廉的MC1496集成模拟相乘器来实现调幅之功能。 DSB信号波形与载波波形的相位关系是：在调制信号正半周期间，两者同相；负半周期间，两者反相。 通过实验了解到了调制度的计算方法 六．课程心得体会 通过本次实验，我们了解了振幅调制的工作原理并掌握了实现AM和DSB的方法，学会计算调制度，具体见实验结论。我们对集成乘法器幅度调制电路有了更好的了解，对他有了更深入的认识，提高了对通信电子电路的兴趣。 和模电实验的单独进行，通电实验增强了团队配合的能力，两个人的有效分工提高了实验的效率，减少了一个人的独自苦恼。
10、北邮2017年电子电路冲刺题及答案
北京邮电大学电子电路（802）模拟试题 模拟部份 一、填空题（共15分，每空0.5分） 1．电子技术分为模拟电子技术和数字电子技术两大部分，其中研究在平滑、连续变化的电 压或电流信号下工作的电子电路及其技术，称为【1】电子技术。 2．PN 结反向偏置时，PN 结的内电场【2】。PN 具有【3】特性。 3．硅二极管导通后，其管压降是恒定的，且不随电流而改变，典型值为【4】伏；其门坎电压V th 约为【5】伏。 4．为了保证三极管工作在放大区，要求： ①发射结【6】偏置，集电结【7】偏置。 ②对于ＮＰＮ型三极管，应使VBC 【8】。 5．放大器级间耦合方式主要有阻容（RC ）耦合、直接耦合和【9】耦合三大类。 6．在三极管组成的三种不同组态的放大电路中，共射和共基组态有电压放大作用，【10】组态有电流放大作用，【11】组态有倒相作用；【12】组态带负载能力强，【13】组态向信号源索取的电流小，【14】组态的频率响应好。 7．场效应管是【15】器件，只依靠【16】导电。 8．石英晶体振荡器是【17】的特殊形式，因而振荡频率具有很高的稳定性。 9．将交流电变换成脉动直流电的电路称为整流电路；半波整流电路输出的直流电压平均值等于输入的交流电压（即变压器副边电压）有效值的【18】倍；全波整流电路输出的直流电压平均值等于输入的交流电压（即变压器副边电压）有效值的【19】倍。 10．差动放大电路中的长尾电阻Ｒe 或恒流管的作用是引人一个【20】反馈。(1分) 11．为了分别达到下列要求，应引人何种类型的反馈： ①降低电路对信号源索取的电流：【21】。 ②当环境温度变化或换用不同值的三极管时，要求放大电路的静态工作点保持稳定：【22】。 ③稳定输出电流：【23】。 12．在构成电压比较器时集成运放工作在开环或【24】状态。 13．某负反馈放大电路的开环放大倍数Ａ=100000，反馈系数Ｆ＝0.01，则闭环放大倍数 【25】。 14．差分式放大电路能放大直流和交流信号，它对【26】具有放大能力，它对【27】具有抑 制能力。 15．乙类功放的主要优点是【28】，但出现交越失真，克服交越失真的方法是【29】。 二、单项选择题(每小题1分，共10分) 1．在本征半导体中掺入（ ）构成P 型半导体。 β≈
2014年公共英语三级阅读理解专项试题(一)
公共英语三级阅读理解专项试题(一) 一、Reading Comprehension（共60小题,共120.0分）Read the following three texts．Answer the questions on each text by choosing A, B, C or D． 第1题 I. Q. stands for "Intelligence Quotient" which is measure of a person's intelligence found by means of an intelligence test. Before marks gained in such a test can be useful as information about a person, they must be compared with some standard, or norm. It is not enough simply to know that a boy of thirteen has scored, say, ninety marks m a particular test. To know whether he is clever, average, or dull, his marks must be compared with the average achieved by boys of thirteen in that test. In 1906 the psychologist, Alfred Binet, devised the standard in relation to which intelligence has since been assessed. Binet was asked to find a method of selecting all children in the schools of Paris who should be taken out of ordinary classes and put in special classes for defectives. The problem brought home to him the need for a standard of intelligence, and he hit upon the very simple concept of" mental age". First, he invented a variety of tests and put large numbers of children of different ages through them. He then found at what age each test was passed by the average child. Binet arranged the various tests in order of difficulty, and used them as a scale by which he could measure every individual. If, for example, a boy aged twelve could only do tests that were passed by the average boy of nine, Binet held that he was three years below average, and that he had a mental age of nine. The concept of mental age provided Binet, and through him, other psychologists with the required standard. It enabled him to state scores in intelligence tests m terms of norm. At first, it was usual to express the result of a test by the difference between the" mental" and the" chronological" age. Then the boy in the example given would be" three years retarded". Soon, however, the" mental ratio" was introduced; that is to say, the ratio of the mental age to the chronological age. Thus a boy of twelve with mental age of nine has a mental ratio of 0.75. The mental age was replaced by the intelligence quotient or" I. Q". Clearly, since the mental age of the average child is equal to the chronological age, the average I. Q. is 100. To judge a child's standard, his marks in a test must be compared with marks gained by ______. A others of the same age
北邮英语阶段1
、单项选择题（共10道小题，共100.0分） 1.――May I see your tickets, please? ――_____________. A.Sure. B.No, you can't. C.No, they are mine. D.Yes, you can. 知识点: 交际英语 学生答案: [A;] 标准答 案: A; 得分: [10] 试题分 值: 10.0 提示: 2.―― Thank you for inviting me. ―― ________________. A.I really had a happy time. B.Oh, it's too late. C.Thank you for coming. D.Oh, so slowly? 知识点: 交际英语 学生答案: [C;] 标准答 案: C; 得分: [10] 试题分 值: 10.0 提示: 3.(错误) ――Could I borrow your car for a few days? ―― _______________. A.Yes, you may borrow. B.Yes, go on. C.Sure, here your are. Enjoy your journey.
D.It doesn't matter.知识点: 交际英语 学生答案: [B;] 标准答 案: C; 得分: [0] 试题分 值: 10.0 提示: 4.――Could I speak to Don Watkins, please? ――_____________ A.Speaking, please. B.Oh, how are you? C.I'm listening. D.I'm Don. 知识点: 交际英语 学生答案: [A;] 标准答 案: A; 得分: [10] 试题分 值: 10.0 提示: 5.――Could you help me with my physics, please? ――___________. A.No, no way. B.No, I couldn't. C.No, I can't. D.Sorry I can't. I have to go to a meeting right now. 知识点: 交际英语 学生答案: [D;] 标准答 案: D; 得分: [10] 试题分 值: 10.0 提示:
北邮电子电路实验函数信号发生器实验报告教材
北京邮电大学 电子电路综合设计实验实验报告 实验题目：函数信号发生器 院系：信息与通信工程学院 班级： 姓名： 学号： 班内序号：
一、课题名称： 函数信号发生器的设计 二、摘要： 方波-三角波产生电路主要有运放组成，其中由施密特触发器多谐振荡器产生方波，积分电路将方波转化为三角波，差分电路实现三角波-正弦波的变换。该电路振荡频率由第一个电位器调节，输出方波幅度的大小由稳压管的稳压值决定；正弦波幅度和电路的对称性分别由后两个电位器调节。 关键词：方波三角波正弦波频率可调幅度 三、设计任务要求： 1．基本要求： 设计制作一个方波-三角波-正弦波信号发生器，供电电源为±12V。 1）输出频率能在1-10KHZ范围内连续可调； 2）方波输出电压Uopp=12V(误差<20%)，上升、下降沿小于10us； 3）三角波输出信号电压Uopp=8V(误差<20%)； 4）正弦波信号输出电压Uopp≥1V，无明显失真。 2．提高要求： 1）正弦波、三角波和方波的输出信号的峰峰值Uopp均在1~10V范围内连续可调； 2）将输出方波改为占空比可调的矩形波，占空比可调范围30%--70% 四、设计思路 1. 结构框图 实验设计函数发生器实现方波、三角波和正弦波的输出，其可采用电路图有多种。此次 实验采用迟滞比较器生成方波，RC积分器生成三角波，差分放大器生成正弦波。除保证良 好波形输出外，还须实现频率、幅度、占空比的调节，即须在基本电路基础上进行改良。 由比较器与积分器组成的方波三角波发生器，比较器输出的方波信号经积分器生成三角
波，再经由差分放大器生成正弦波信号。其中方波三角波生成电路为基本电路，添加电位器调节使其频率幅度改变；正弦波生成电路采用差分放大器，由于差分放大电路具有工作点稳定、输入阻抗高、抗干扰能力较强等优点，特别是作为直流放大器时，可以有效地抑制零点漂移，因此可将频率很低的三角波变换成正弦波。 2．系统的组成框图 五、分块电路与总体电路的设计 1．方波—三角波产生电路 电源电路 方波-三角波 发生电路 正弦波发生电路 方波输出 三角波输出 正弦波输出
电子线路期末试卷及答案
(1)在半导体内部，只有电子是载流子。 (2)在N型半导体中，多数载流子是空穴，少数载流子是自由电子。 (3）一般来说，硅晶体二极管的死区电压(门槛电压)小子锗晶体二极管的死区电压。 (4)在外电场作用下，半导体中同时出现电子电流和空穴电流。 (5)晶体三极管出现饱和失真是由于静态电流I CQ选得偏低。 (6)用万用表测某晶体二极管的正向电阻时，插在万用表标有“十”号插孔中的测试棒(通常是红色棒)所连接的二极管的管脚是二极管的正极，另一电极是负极。 (7)三极管放大电路工作时，电路中同时存在直流分量和交流分量；直流分量表示静态工作点，交流分量表示信号的变化情况。 (8)在单管放大电路中，若V G不变，只要改变集电极电阻Rc的值就可改变集电极电流Ic的值。 (9)两个放大器单独使用时，电压放大倍数分别为A v1、A v2，这两个放大器连成两级放大器后，总的放大倍数为A v，A v= A v1+A v2。 (10)晶体二极管在反向电压小于反向击穿电压时，反向电流极小；当反向电压大于反向击穿电压后，反向电流会迅速增大。 (1)当晶体二极管的PN结导通后，则参加导电的是( )。 A．少数载流子 B．多数载流子 C．既有少数载流子又有多数载流子 (2)在共发射极单管低频电压放大电路中，输出电压应视为( )。 A．v o＝i c R c B．v o＝-R c i c C．v o＝-I c R c (3)用万用表欧姆挡测量小功率晶体二极管性能好坏时，应把欧姆挡拔到( )。 A．R×100Ω或R×1000Ω挡 B．R×1Ω C．R×10KΩ挡 (4)当晶体二极管工作在伏安特性曲线的正向特性区，而且所受正向电压大于其门槛电压时，则晶体二极管相当于()。 A．大电阻 B．断开的开关 C．接通的开关 (5)晶体三极管工作在饱和状态时，它的I C将( )。 A．随I B增加而增加 B．随I B增加而减小 C．与I B无关，只决定于R C和V G (6)共发射极放大器的输出电压和输入电压在相位上的关系是( )。 A．同相位 B．相位差90° C．相位差180° (7)NPN型三极管放大电路中，当集电极电流增大时，则晶体三极管( )。 A．基极电流不变； B．集电极对发射极电压V CE下降； C．集电极对发射极电压V CE上升 (8)当晶体三极管发射结反偏时，则晶体三极管的集电极电流将( )。 A．增大 B．反向 C．中断 （9）在基本放大电路中，基极电阻R B的作用是( )。 A．放大电流 B．调节偏置电流I BQ C．把放大了的电流转换成电压； D．防止输入信导被短路。 （10）三极管的两个PN结都反偏时，则三极管所处的状态是（）。 A.放大状态 B.饱和状态 C.截止状态 三．填充题（2’×10） (1)晶体三极管I E、I B、I C之间的关系式是__________________，△I C／△I B的比值叫____________________。 (2)PN结具有____________________性能，即：加____________________电压时PN结导通；加_______________电压时PN结截止。 (3)当晶体二极管导通后，则硅二极管的正向压降为_________V，锗二极管的正向压降为__________V。 (4)NPN型晶体三极管的发射区是____________型半导体，集电区是____________型半导体，基区是____________型半导体。 (5)晶体二极管因所加_______________________电压过大而__________________，并且出现__________________的现象，称为热击穿。 (6)某固定偏置放大器中，实测得三极管集电极电位V C≈V G，则该放大器的三极管处于________________________工作状态。 (7)晶体三极管的穿透电流I CEO随温度的升高而增大，由于锗三极管的穿透电流比硅三极管_____________，所以热稳定性____________三极管较好。
2014年9月PETS全国公共英语等级考试二级听力试题(即：2014年9月贵州省高考英语听力考试)
2014年9月PETS全国公共英语等级考试二级听力试题 （即：2014年9月贵州省高考英语听力考试真题） 贵州省凯里一中刘治豪编辑整理 20160101 版权所有，盗用必究 第一节 听下面5段对话。每段对话后有一个小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。听完每段对话后，你都有10秒钟的时间来回答有关小题和阅读下一小题。每段对话仅读一遍。 1. What is the woman going to do? A. Leave early. B. Make a speech. C. Join the discussion. 2. Which color shirt will the man buy? A. Red. B. Green. C. White. 3. What is the probable relationship between the speakers? A. Strangers. B. Neighbors. C. Co-workers. 4. What do you know about the man? A. He’s going to Mexico. B. He’s worried about the food. C. He’s been to the hotel before. 5. What will the woman probably do for the man? A. Clean the house. B. Carry the boxes. C. Cook the dishes. 第二节 听下面5段对话或独白。每段对话或独白后有几个小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。听每段对话或独白前，你将有时间阅读各个小题，每小题5秒钟；听完后，各个小题将给出5秒钟的作答时间。每段对话或独白读两遍。 听下面一段对话，回答第6和第7题。 6. What does Harris probably want to do with Olivia? A. Have lunch. B. Watch a movie. C. Go to her office. 7. When will Harris and Olivia meet? A. At 6:50. B. At 7:10. C. At 10:00. 听下面一段对话，回答第8至第10题。 8. What does the woman like about the armchair? A. Its size. B. Its color. C. Its design. 9. What do we know about the speakers’ armchair at home? A. It is badly broken. B. It is heavy looking. C. It is brown in color. 10. What will the speakers probably do about the armchair? A. Wait for a sale. B. Buy it right away.
2014年北邮大学英语2阶段三作业
一、阅读理解（共1道小题，共25.0分） 1. A pretty, well―dressed young lady stopped a taxi in a big square, and a said to the driver, "Do you see that young man at the other side of the square?" "Yes," said the taxi driver. The young man was standing outside a restaurant and looking impatiently (不耐烦地) at his watch every few seconds. "Take me over there," said the young lady. There were a lot of cars and buses in the square, so the taxi driver asked, "Are you afraid to cross the street?" "Oh, no!" said the young lady. "But I promised that I would meet the young man for lunch at one o' clock, and it is now a quarter to two. If I arrive in a taxi, it will at least seem as if I had tried not to be late." 1.How did the young woman get to the square? A.She arrived in a taxi. B.She drove there in a car. C.She got there by bus. D.The story doesn't tell us. 2.Why did the lady stop the taxi? A.Because she didn't want to be late for her appointment (约会). B.Because she wanted to get out of the taxi. C.Because she wanted to go to the restaurant in it. D.Because she was afraid of walking across the street. 3.The young man at the other side of the square_______. A.had probably been waiting for a long time B.had some problem with his watch C.was probably a waiter of the restaurant D.was someone the young lady didn't want to see 4.The young lady was_______. A.clever at making excuse B.not late at all C.45 minutes earlier D.15 minutes late 5.Had she tried not to be late? A.Yes, she had tried her best. B.No, she was just pretending that she had tried. C.Yes, she had tried but she was still late.