【单选题】
电流为5A，内阻为2Ω的电流源变换成一个电压源时，电压源的电动势和内阻为___
A. 10V，2Ω
B. 2.5V，2Ω
C. 0.4V，2Ω
D. 4V，2Ω
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相关试题
【单选题】
额定电压都为220V的40W、60W、100W三灯泡串联在220V的电源中，它们的发热量由大到小排列为___
A. 100W 60W 40W
B. 40W 60W 100W
C. 100W 40W 60W
D. 60W 100W 40W
【单选题】
在正弦交流电的解析式i=ImSin(ωt +φ)中，φ表示___
A. 频率
B. 相位
C. 初相位
D. 相位差
【单选题】
正弦交流电压u=100Sin(628t + 600)V，它的最大值为___。
A. 100 V
B. 100 V
C. 60V
D. 628 V
【单选题】
能表示容性电路电压与电流关系的相量图是___。
【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。
推荐试题
【单选题】
Which name is not mentioned in the film? ___
A. Nicole Kidman.
B. Hugh Jackman.
C. George Clooney.
D. Robin Williams.
【单选题】
Which of the following statement is not true about “Life in the Freezer”? ___
A. It was a documentary film.
B. It was made by National Geographic and the BBC.
C. It was a story of the amazing life of Emperor penguins.
D. The
E. mperor penguin sang to each other to find a mate and made friends.
【单选题】
What should you do during a high-pressure periods? ___
A. Lock yourself in a room with your work.
B. Leave your work and go on a vocation.
C. Tell your boss you can’t finish your work.
D. Get together with people who will revitalize and inspire you.
【单选题】
Which of the following is the correct description of TempWorld? ___
A. The era of guaranteed jobs is history.
B. We are all temporary workers.
C. You have to equip yourself with the skills.
D. All of the above.
【单选题】
What should a career activist do? ___
A. Being a career activist means concentrating on daily business.
B. Being a career activist means you can do a business as long as it meets your short-term needs.
C. A career activist should take the long view of his career.
D. A career activist should plan everything in advance.
【单选题】
What should you do in the TempWorld? ___
A. In TempWorld you must withstand disappointment, juggle stressful situations, and handle pressure.
B. You must learn from your setbacks and use them to your advantage in the future.
C. Things always go well for successful people because they are honest.
D. Both A and B.
【单选题】
Which of the following statements is Not True? ___
A. Your boss may be willing to change his behavior than your think.
B. Some managers don’t care how much their words or actions upset staffers.
C. You should tell your managers how their outbursts make you feel.
D. If the boss values your work, he may stop his abusiveness.
【单选题】
Which of the following public places is NOT mentioned that have banned mobiles? ___
A. restaurants
B. gas stations
C. theatres
D. museums
【单选题】
What happened when the cellphone of the speaker’s friend rang? ___
A. His friend answered the phone and the speaker became invisible to his friend.
B. They answered the phone together.
C. The speaker threw away his friend’s cellphone.
D. His friend hung up the phone and kept talking to the speaker. (C)
【单选题】
What happened to the man? ___
A. He had a car accident.
B. He had his arms broken.
C. He lost his mobile phone.
D. He was not able to use his mobile because he was in a remote area.
【单选题】
Which of the following is NOT true? ___
A. Today there are about 400 million cellphone owners.
B. Today there are about 300 million Personal Computer subscribers.
C. Cellphones will be more often used.
D. Cellphones will completely replace Personal Computers.
【单选题】
Which of the following is true? ___
A. Ellen Johnson-Sirleaf stayed in her country during the nation’s civil war.
B. She is still working for the United Nations.
C. She is the first woman ever elected president of an Asian country.
D. She is a Liberia.
【单选题】
What do you know about the solar eclipse? ___
A. Only hundreds of people gazed at it.
B. It was caused by the earth passing in front of the moon.
C. It was not often seen.
D. It started in Mongolia and ended in Brazil.
【单选题】
What is true about this meeting between the USA and China? ___
A. It was a meeting between Xi Jinping and Donald Trump.
B. It was the first time that the Chinese president had visited the United States.
C. The issue of the Olympics was discussed.
D. South Korea’s nuclear weapons program was discussed.
【单选题】
In which year did the station’s first permanent crew arrived? ___
A. 1998
B. 2000
C. 2002
D. 2003
【单选题】
If elected, ________________. ___
A. Richardson would be the first Hispanic President.
B. Clinton would be the first African-American President.
C. Romney world be the first Hispanic President.
D. Clinton would be the first Mormon President.
【单选题】
What are the things that the speaker’s inner and outer life based on? ___
A. Money
B. Health
C.
D. elicious food
【单选题】
What kind of things has its own reason for existing? ___
A. Questioning
B. The structure of reality
C. Curiosity
D. The mysteries of eternity
【单选题】
Who are so full of doubts? ___
A. Fools and fanatics
B. Wise people
C. Professors
D. University students
【单选题】
To the speaker, what kind of things always win in life? ___
A. Truth and love
B. Power and status
C. Great minds
D. Money and material
【单选题】
What’s the key word of the speaker? ___
A. Love
B. Power
C. Freedom
D. Curiosity
【单选题】
What happened to the man? ___
A. He committed identity theft.
B. He was put in prison.
C. He reported a case of theft to police.
D. He robbed a bank.
【单选题】
What is the attitude of Mrs. Washington? ___
A. She tries to cover up for little George.
B. She thinks Mr. Washington should not ask George directly.
C. She encourages George to chop down the tree.
D. She thinks Mr. Washington should put the blame on the sharp axe.
【单选题】
What do Nancy’s colleagues think about her transgender transition? ___
A. They think it is ridiculous.
B. They make a big fuss about it.
C. They take it lightly.
D. They are sympathetic.
【单选题】
What are the two women talking about? ___
A. They are talking women’s liberation.
B. They are talking about an ideal husband.
C. They want a rewarding job.
D. They are talking about women’s choice between family and career.
【单选题】
According to what you’ve heard, which of the following is NOT true? ___
A. The two ten-minute workouts help people get into shape in a short time.
B. The two ten-minute workouts are designed for the people of certain level of fitness.
C. The two ten-minute workouts help people to lose weight and to be vigorous.
D. The two ten-minute workouts are suitable for most people.
【单选题】
What does Cindy say about visiting Costa Rica in June? ___
A. It is bad because June falls in the rainy season.
B. It is bad because there is almost no sunshine in June.
C. It is not bad because it seldom rains on the coast.
D. It is not bad because it does not rain all the time and in all the places.
【单选题】
What did the professor say about the translation of idioms across language? ___
A. Almost all idioms are translatable and can be universally used.
B. Idioms are hardly translatable and cannot be universally used.
C. Not all idioms are translatable but many have translations in other language.
D. All idioms are translatable and tend to become international.
【单选题】
According to Professor Randal, which of the following is true for SAT II? ___
A. It tests your critical thinking and problem-solving skills.
B. It is more content oriented.
C. It is designed to measure subject-area knowledge.
D. It is designed to measure achievement in
E. nglish, math, reading, and science.
【单选题】
The movie in IMAX format adds the amazing effects except ___________. ___
A. the effect of sound
B. the effect of view
C. the effect of landscape
D. the effect of mystery
【单选题】
What can we learn from the conversation? ___
A. Nobody thinks he is under stress.
B. People should avoid stress completely.
C. Stress is a normal state of affairs.
D. Nobody is subject to stress.
【单选题】
What is Tom’s attitude towards the mobile phone? ___
A. It is very convenient to send text messages.
B. People have to put up with the inconvenience of using mobile phones.
C. He feels important when he uses his mobile phone in public.
D. He cannot live a day without his mobile phone.
【单选题】
Where did Helena start learning Dutch? ___
A. Spain
B. Holland
C. Sri Lanka
D. Indonesia
【单选题】
According to what the broadcaster says about what happened when the blackout occurred, which of the following is not true? ___
A. People crowded the streets of New York.
B. Throngs of people walked across the bridge, screaming and cursing.
C. The blackout stopped subways, buses and turned off traffic lights.
D. Many people are thinking of hitching a ride.
【单选题】
Who is Dr. Burkey? ___
A. The anchor
B. The questioner
C. A student
D. A clinical psychologist.
【单选题】
Which is true about Gandhi’s nonviolence? ___
A. There will be no pains and defeats when people use nonviolence.
B. People should be prepared to die like a soldier when they use nonviolence.
C. Nonviolence means that you have to accept injustice.
D. Soldiers can use violence against violence.
【单选题】
肖东和外祖父是___
A. 直系血亲
B. 直系姻亲
C. 旁系血亲
D. 旁系姻亲
【单选题】
按罗马法的亲等算法，小杨和叔叔的孙子是___
A. 三等亲
B. 四等亲
C. 五等亲
D. 六等亲
【单选题】
甲（男）的外祖母乙是丙（女）的父亲丁的胞姊，因此___
A. 乙是丙的姑母，丁是甲母的舅父
B. 乙是丙的姨母，丙是乙的甥女
C. 乙是丙的舅母，丁是甲母的叔父
D. 乙是丙的婶母，丙是乙的侄女
【单选题】
下列各种亲属关系中，属于直系拟制血亲的有___
A. 外祖父母与外孙子女
B. 养父母与养子女
C. 祖父母与孙子女
D. 继父母与未受其抚养教育的继子女
