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导入试题
【单选题】
使用电解电容时___。
A. 负极接高电位,正极接低电位
B. 正极接高电位,负极接低电位
C. 正极接高电位,负极也可以接高电位
D. 不分正负极
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答案
B
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【单选题】
开关接1时,电压表的读数为___。
A. 0V
B. 0.2V
C. 1.96V
D. 2V
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开关接2时,电流表的电流为___。
A. 0A
B. 10A
C. 0.2A
D. 约等于0.2A
【单选题】
开关接1时,电流表中流过的短路电流为___。
A. 0A
B. 0.2A
C. 10A
D. 约等于0.2A
【单选题】
正弦交流电常用的表达方法有___。
A. 解析式表示法
B. 波形图表示法
C. 相量表示法
D. 以上都是
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电感两端的电压相位超前电流___。
A. 90°
B. 180°
C. 360°
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电容两端的电压相位滞后电流___。
A. 30°
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【单选题】
应用戴维南定理求含源二端网络的输入等效电阻是将网络内各电动势___
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B. 并联
C. 短接
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LC 选频振荡电路,当电路频率等于谐振频率时,电路性质为___。
A. 电阻性
B. 感性
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【单选题】
阻值为4Ω的电阻和容抗为3Ω的电容串联,总复数阻抗为___
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电动势为10V,内阻为2Ω的电压源变换成电流源时,电流源的电流和内阻是___
A. 10A,2Ω
B. 20A,2Ω
C. 5A,2Ω
D. 2A,5Ω
【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
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【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___
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B. 40W 60W 100W
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【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___。
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B. 100 V
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【单选题】
能表示容性电路电压与电流关系的相量图是___。
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B.
C.
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【单选题】
如图判断同名端为___
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【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。
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B. 基尔霍夫电流
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【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___
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【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。
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【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。
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B. 并联
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【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___。
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【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___。
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【单选题】
1杂质半导体中多数载流子的浓度取决于___
A. 温度
B. 杂质浓度
C. 电子空穴对数目
【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___
A. 相同
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【单选题】
3光敏二极管应在___下工作
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【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
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【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___。
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【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。
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B. 反偏 E、正向导通 F、截止
【单选题】
7三端集成稳压器CW7812的输出电压是___。
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B. 5V
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【单选题】
8三端集成稳压器CXX7805的输出电压是___
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【单选题】
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A. 有微弱电流
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【单选题】
10二极管两端正向电压大于___电压时,二极管才导通。
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【单选题】
11当温度升高时,二极管的反向饱和电流 ___ 。
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B. 减小;
C. 不变;
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【单选题】
12硅二极管的正向导通压降比锗二极管的___ 。
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【单选题】
13三端集成稳压器 CW7906的输出电压是___
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14稳压管的工作是利用伏安特性中的___。
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15二极管具有___
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【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。
A. A灯
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【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
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【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___。
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( ) 26. Where does the writer of "The little Prince" come from? A.England. B.France. C.America. D.China.
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B. B
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【单选题】
( ) 27. What does the prince do after the fox tells him a secret? A.He cares more about a flower and a sheep. B.He meets many more strange adults on other planets. C.He realizes his love for the rose and he goes back to his planet.   D.He discovers interesting things such as a snake, other roses and a fox
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【单选题】
( ) 28. What does "The little Prince" mainly talk about? It' s about _________. A.the adult world B.the planet B -612 C.a rose and a fox D.the adventure of a young prince
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【单选题】
( ) 29. What is the writer's main purpose(目的)in writing this passage?    A.To tell the readers his life story.    B.To tell people what kind of person his father was.    C.To tell the readers what present he got from his father.    D. To let people know how poor he was.
A. A
B. B
C. C
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【单选题】
( ) 30. Why did the father not ask his son not to do this and do that?    A.Because he felt quite confident of his son.    B.Because he was born from a poor family.    C.Because he was a man of few words.    D.Because he didn't want to be much too strict with his son.
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【单选题】
( ) 31. What would someone learn from this passage?    A.How to live by oneself. B.How to stand on one's own feet.    C.What a good father should do. D.What the self-important is like.
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【单选题】
( ) 32. What may be the proper Chinese for the underlined part in the passage?    A.闲暇时光 B.学费 C.精神空虚 D.经济不足
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【单选题】
( ) 33. Why did Natalie Smith pay for the six cars behind her? A. She had seven tickets. B. She hoped to please others. C. She knew the car drivers well. D. She wanted to show kindness.
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【单选题】
( ) 34. Judy Foreman copied down the phrase because she ___ . A. thought it was beautifully written B. wanted to know what it really meant C. decided to write it on a warehouse wall D. wanted her husband to put it up in the classroom
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【单选题】
( ) 35. Who came up with the phrase according to the passage? A. Judy Foreman. B. Natalie Smith. C. Anne Herbert D. Alice Johnson.
A. A
B. B
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【单选题】
( ) 36. What can we infer from the last paragraph? A. People should practice random kindness to those in need. B. People who receive kindness are likely to offer it to others. C. People should practice random kindness to strangers they meet. D. People who receive kindness are likely to pay it back to the giver.
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【单选题】
( ) 37.The greatest river for navigation is ___________. A. the Nile B. the Amazon C. the Mekong D. the Mississippi
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【单选题】
( ) 38. From a dam, people can use the water for ___________. A. keeping the rivers clean B. only making electricity C. irrigation and making electricity D. washing clothes
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B. B
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【单选题】
( ) 39. The water in the river is polluted because of _____________. A. people's drinking water too much B. people's swimming in the river too much C. chemicals and other materials D. people's building a dam across a river
A. A
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( ) 40. The best title of the passage is ___________. A. Rivers in Cities B. The importance of Rivers C. Transportation D. Natural Resources
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