相关试题
【单选题】
电路中___定律指出：流入任意一节点的电流必定等于流出该节点的电流。
A. 欧姆
B. 基尔霍夫电流
C. 楞次
D. 基尔霍夫电压
【单选题】
已知电源电压为12 V ,四只相同灯泡的工作电压都是6 V，要使灯泡都能正常工作，则灯泡应___
A. 全部串联
B. 两只并联后与另两只串联
C. 两两串联后再并联
D. 全部并联
【单选题】
用戴维南定理分析电路“入端电阻”时，应将内部的电流源___处理。
【单选题】
任何一个含源二端网络都可以用一个适当的理想电压源与一电阻___来代替。
A. 串联
B. 并联
C. 串联或并联
D. 随意联接
【单选题】
用交流电流表测得交流电流10A，则电路中电流的最大值为___。
A. 10A
B. 14.1A
C. 20A
D. 70.7A
【单选题】
如右图所示电路中，已知各支路的电流I1=I2=10A， 则电路的总电流I为___。
A. 20A
B. 0 A
C. 14.1A
D. 50A
【单选题】
1杂质半导体中多数载流子的浓度取决于___
【单选题】
2在电场作用下，空穴与自由电子运动形成的电流方向___
【单选题】
4下列半导体材料哪一种的热敏性突出“导电性受温度影响最大”？___
A. 本征半导体
B. N型半导体质
C. P型半导体
【单选题】
5用万用表电阻挡检测某一个二极管时，发现其正、反电阻均近于1000KΩ，这说明该二极管是属于___。
A. 短路状态；
B. 完好状态；
C. 断路状态；
D. 极性搞错。
【单选题】
6稳压二极管是一个可逆击穿二极管，稳压时工作在___状态。
【单选题】
7三端集成稳压器CW7812的输出电压是___。
【单选题】
8三端集成稳压器CXX7805的输出电压是___
【单选题】
9一个平衡PN结，用导线将P区和N区连起来，而导线中___。
A. 有微弱电流
B. 无电流
C. 有瞬间微弱电流
【单选题】
10二极管两端正向电压大于___电压时，二极管才导通。
【单选题】
11当温度升高时，二极管的反向饱和电流 ___ 。
A. 增大；
B. 减小；
C. 不变；
D. 无法判定。
【单选题】
12硅二极管的正向导通压降比锗二极管的___ 。
【单选题】
13三端集成稳压器 CW7906的输出电压是___
【单选题】
14稳压管的工作是利用伏安特性中的___。
A. 正向特性
B. 反向特性
C. 反向击穿特性
【单选题】
15二极管具有___
A. 正向特性
B. 反向特性
C. 单向导电特性
D. 反向击穿特性
【单选题】
16图中D1-D3为理想二极管，A，B，C灯都相同，试问___灯最亮。
【单选题】
18在单相桥式整流电容滤波电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
19在单相桥式整流电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
20在半波整流电容滤波电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
21在半波整流电路中，设U2为其输入电压，输出电压的平均值约为___。
A. U0=0.45U2
B. U0=1.2U2
C. U0=0.9U2
D. U0=1.4U2
【单选题】
22温度影响了放大电路中的___，从而使静态工作点不稳定。
A. 电阻；
B. 电容；
C. 三极管；
D. 电源。
【单选题】
23用直流电压表测得放大电路中某三极管各极电位分别是2V、6V、2.7V，则三个电极分别是___。
A. [B、C、E]
B. [C、B、E]
C. [E、C、B]
【单选题】
24共射极放大电路的交流输出波形上半周失真时为___
【单选题】
25三极管的反向电流ICBO是由___组成的。
A. 多数载流子
B. 少数载流子
C. 多数载流子和少数载流子
【单选题】
27如果在NPN型三极管放大电路中测得发射结为正向偏置，集电结也为正向偏置，则此管的工作状态为___
A. 放大状态；
B. 截止状态；
C. 饱和状态；
D. 不能确定。
【单选题】
28在以下三种电路中输入电阻最大的电路是___。
A. 共基放大电路
B. 共集放大电路
C. 共射放大电路
【单选题】
29在以下三种电路中既能放大电流，又能放大电压的电路是___。
A. 共基放大电路
B. 共集放大电路
C. 共射放大电路
【单选题】
30在以下三种电路中输出电阻最小的电路是___；
A. 共基放大电路
B. 共集放大电路
C. 共射放大电路
【单选题】
当PNP型晶体管工作在放大区时，各极电位关系为uC ___uB。
【单选题】
32当PNP型晶体管工作在放大区时，各极电位关系为uB___uE 。
【单选题】
33测得NPN型三极管上各电极对地电位分别为，，，说明此三极管处在___。
A. 放大区
B. 饱和区
C. 截止区
D. 反向击穿区
【单选题】
34若使三极管具有电流放大能力，必须满足的外部条件是___。
A. 发射结正偏、集电结正偏
B. 发射结反偏、集电结反偏
C. 发射结正偏、集电结反偏
D. 发射结反偏、集电结正偏
【单选题】
35在由PNP晶体管组成的基本共射放大电路中，当输入信号为1KHz、5mV的正弦电压时，输出电压波形出现了顶部削平的失真。这种失真是___ 。
A. 饱和失真
B. 截止失真
C. 交越失真
D. 频率失真
【单选题】
36在由PNP晶体管组成的基本共射放大电路中，当输入信号为1KHz、5mV的正弦电压时，输出电压波形出现了底部削平的失真。这种失真是___ 。
A. 饱和失真
B. 截止失真
C. 交越失真
D. 频率失真
推荐试题
【单选题】
Q1: Why is surfing the man’s favorite activity?___
A. Because he likes the sunny weather.
B. Because he wants to challenge himself .
C. Because it can help solve his sleeping problem .
D. Because it can help him forget all his troubles .
【单选题】
Q2: What is the woman going to do this weekend?___
A. To go sailing .
B. To go surfing .
C. To go to the beach .
D. To go to her nephew's .
【单选题】
Q3: What does the woman love doing?___
A. Going to visit relatives.
B. Enjoying the warm sun on the beach .
C. Building sand castles with her niece and nephew .
D. Playing in the sand and jumping in the waves .
【单选题】
Q4: What does the man remember doing with his brothers?___
A. Surfing in the sea .
B. Collecting seashells .
C. Building sand castles .
D. Jumping in the waves .
【单选题】
Q1: According to the survey, what percentage of British adults watched TV in theirfree time?___
A. 89 percent .
B. 84 percent .
C. 76 percent .
D. 71 percent .
【单选题】
Q2: Which age group would be the most likely to visit their friends and relatives?___
A. People aged 16 to 24
B. People aged 25 to 34 .
C. People aged 16 and over .
D. People aged 55 and over .
【单选题】
Q3: What does the speaker say about listening to music as a leisure activity for British people?___
A. People aged 16 to 24 preferred listening to music most .
B. It was getting more and more popular among the British people .
C. It was the third most popular activity among people aged 55 and over .
D. People aged 25 to 34 listened to music more often than those aged 16 to 24 .
【单选题】
Q4: According to the survey, how are leisure activities related to age?___
A. Older people go out to pubs more often . frequently .
B. Younger people go to the cinema less frequently.
C. Older people spend more time reading and gardening .
D. Younger people spend less time visiting friends and family .
【单选题】
Q1: Why was the girl excited?___
A. She is going to have a lot of vanilla ice cream .
B. She won the spelling competition at her school .
C. She is going to the state capital for a competition .
D. She "excellence"correctly,but others didn't .
【单选题】
Q2: What happened when the man was 13 years old?___
A. His family moved to Sacramento to settle down .
B. His family bought him a new suit and a new tie .
C. He went to Sacramento for a spelling competition .
D. He won the first prize in the state spelling competition .
【单选题】
Q3: Why did the man’s mom give him a big hug?___
A. To make him feel better after he lost the first prize .
B. To apologize for not buying him some ice cream .
C. To wish him good luck in the next competition .
D. To congratulate him on winning the first prize .
【单选题】
Q4: What color is the girl going to wear for her next competition?___
A. Red .
B. Blue .
C. Green .
D. Yellow .
【单选题】
Q1: What is this passage mainly about?___
A. Superstitions and science .
B. Tips on how to have good luck .
C. Superstitions in the United States .
D. Rational and superstitious societies .
【单选题】
Q2: According to the passage, what is considered as bad luck?___
A. Walking under a ladder .
B. Dreaming of a black cat .
C. Hanging a mirror in the house .
D. Stepping on one's own shadow .
【单选题】
Q3: Why is it considered bad luck to see a black cat crossing one’s path?___
A. Because black cats look like witches . e witches .
B. Because black cats were thought to be witches .
C. Because black cats bring seven years of bad luck .
D. Because black cats are hard to notice in darkness .
【单选题】
Q4: According to the passage, what will bring people good luck?___
A. Breaking a mirror on purpose .
B. Catching a falling leaf on one's birthday .
C. Finding a on the ground and picking it up .
D. Dreaming of blowing out the candles in one blow .
【单选题】
Q1: How long will the woman spend on her way to and from work by high-speed train?___
A. 4 hours .
B. 2 hours .
C. 1.5 hours .
D. 45 minutes .
【单选题】
Q2: When does the woman arrive back home by subway?___
A. At 8 .
B. At 7 .
C. At 6 .
D. At 5 .
【单选题】
Q3: According to the woman, in what way will the new high-speed train be a big help to her?___
A. She can either read or rest a little on the train .
B. She can read and respond to emails onthe train .
C. She can travel to many different parts of the city .
D. She can go shopping on her way home from work .
【单选题】
Q4: How will the new high-speed train affect the man?___
A. He can take the train to the old part of the city .
B. He can save a lot of money when he takes the train .
C. He can save 20 minutes to go to work with the train .
D. He can take the train to the airport instead of driving .
【单选题】
Q1: How much time on average do Americans spend on their way to work?___
A. About an hour .
B. More than an hour .
C. About half an hour .
D. More than one and a half hours .
【单选题】
Q2: What is the present situation about Americans’ commuting to work?___
A. More and more Americans spend over an hour getting to work .
B. Over 10 percent of Americans spend less than an hour getting to work .
C. Only New York people spend more than 90 minutes getting to work .
D. Over 10 percent of Americans spend more than 90 minutes getting to work .
【单选题】
Q3: Why does Steven choose to have an extreme commute?___
A. Because gas prices are not high .
B. Because the commute is not tiring .
C. Because he can attend a better school .
D. Because he can have his favorite lifestyle .
【单选题】
Q4: Which of the following is the disadvantage of long commutes?___
A. Traffic jams .
B. Expensive housing .
C. Poorer life quality .
D. A tiring and boring trip .
【单选题】
Q1: What did Katy like about Jason’s last Halloween party?___
A. She liked playing an interesting game .
B. She enjoyed seeing many of her old friends .
C. She enjoyed wearing her Halloween costume .
D. She liked the decorations in Jason's front yard .
【单选题】
Q2: What is the actual reason that Katy doesn’t want to attend Jason’s party?___
A. None of her friends likes Jason .
B. None of Jason's guests is young .
C. She wants to go to Linda's party ..
D. She went to Jason's party last year .
【单选题】
Q3: What is special about Linda’s party?___
A. The party will last four hours .
B. Six people will attend the party .
C. They will have huge bags of candy .
D. They will play a new game called "GuessWho ".
【单选题】
Q4: What will Katy do to solve her problem?___
A. Go to Jason's party .
B. Go to Linda's party .
C. Attend both Jason's and Linda's parties .
D. Celebrate Halloween with her parents .
【单选题】
Q1: What is special about this year’s Black Friday shopping?___
A. Some stores offered bigger holiday discounts .
B. Some stores provided more choices of nightlife.
C. Some stores made efforts to attract young people .
D. Some stores opened much earlier than they used to .
【单选题】
Q2: Why did some stores open at midnight on Thanksgiving night?___
A. To attract young customers .
B. To beat other stores for sale.
C. To let people sleep late the next day .
D. To keep people stay up for the night .
【单选题】
Q3: How many Black Friday shoppers were reported to go to the shops at midnight this year?___
A. 24 percent .
B. 37 percent .
C. 9.5 percent .
D. 23.5 percent .
【单选题】
Q4: What can we learn about the 15-year-old Jenny?___
A. She and her cousins went back home at midnight .
B. She liked the traditional 4 a.m. Black Friday.
C. She preferred midnight shopping to early morning shopping .
D. She and her cousins got up very early to buy discounted items .
【单选题】
Q1: Why did the woman decide to do a triathlon?___
A. Because she did it in college .
B. Because she wanted to be tough .
C. Because her sister did it and liked it .
D. Because her sister said it was good for her .
【单选题】
Q2: When did the man first do a triathlon?___
A. Last year .
B. In college .
C. Last week .
D. In high school .
【单选题】
Q3: How does the man feel about running?___
A. Boring.
B. Scaring .
C. Exciting .
D. Interesting .
【单选题】
Q4: Why doesn’t the woman like swimming in the triathlon?___
A. Because she fears that a big fish might eat her .
B. Because she fears that she would get lost in lakes .
C. Because she doesn't want to scare away small fishes .
D. Because she doesn't like swimming with many people .
【单选题】
Q1: What is the ratio of positive to negative emotions that can make a person happier?___
A. 1:3.
B. 3 :1.
C. 1 :10 .
D. 10 :1.
【单选题】
Q2: What is the most exciting finding about increasing positive emotions?___
A. It improves relationships .
B. It leads to greater success .
C. It helps develop creativity .
D. It contributes to good health .
【单选题】
Q3: What does the speaker say about negative feelings?___
A. People should turn every negative feeling around .
B. Negative feelings can sometimes have positive effects .
C. Negative feelings often cause people to make mistakes .
D. People should never show negative feelings in public places .
【单选题】
Q4: What is the main idea of the passage?___
A. People should learn to manage their emotions .
B. People should be patient with their negative feelings .
C. People should learn to analyze causes of unhappiness .
D. People should identify as many positive feelings as possible .
