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
推荐试题
【单选题】
24.In fact, my parents are not only kind to me, but also strict ________ me.
A. at B. to C. for D. with
【单选题】
25. The boy_____ a yellow sweater can_____ himself now．
A. wearing; dress B. putting on; wear C. put on; dress D. dressing;
【单选题】
( ) 26. Where does the writer of "The little Prince" come from?
A．England． B．France． C．America． D．China．
【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．
【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
【单选题】
( ) 29. When a baseball player hits the ball, he must ______ to get a point.
A. run to each base freely
B. touch the home plate first
C. touch all the bases with his hands
D. run to each base in order and touch it with his foot
【单选题】
( ) 30. When was the importance of touching all the bases shown?
A. Before the baseball rules made.
B. At the end of the 1974 baseball seasons.
C. At the start of the 1974 baseball seasons.
D. In the second week of 1974.
【单选题】
( ) 31. Who hit home run number 715?
A. Babe Ruth. B. Hank Aaron. C. Babe Ruth’s partner. D. Hank Aaron’s friend.
【单选题】
( ) 32. What does the expression “to touch all bases” mean?
A. To try your best to set a new record.
B. To get a chance to be the greatest hitter.
C. To do what is needed to finish an activity.
D. To solve the problems successfully.
【单选题】
( ) 33. The Chinese Yellow Sea Wetlands are in the _______ of China．
A．south B．east C．west D．north
【单选题】
( ) 34. Usually the weather in the wetlands is _______．
A．hot B．pleasant C．cold D．dry
【单选题】
( ) 35. The World Wetlands Day is on _______．
A．February 2 B．June 25 C．April 22 D．March 22
【单选题】
( ) 36. We must protect wetlands because _______．
A．they are home for wildlife B．they can prevent flood
C．they can offer food to the animals and birds D．all of the above
【单选题】
( ) 37.The greatest river for navigation is ___________.
A. the Nile B. the Amazon C. the Mekong D. the Mississippi
【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
【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
【单选题】
( ) 40. The best title of the passage is ___________.
A. Rivers in Cities B. The importance of Rivers
C. Transportation D. Natural Resources
【单选题】
1.—Hello! This is Henry Speaking．I’d like to speak to your father．
—Sorry, he has Shanghai．
A. been in B. been to C. come to D. gone to
【单选题】
2. — It’s difficult for the village children to cross the river for school．
— I think a bridge ______ over the river．
A. was built B. is being built C. has been built D. should be built
【单选题】
3. —Where would you like to go, Jinan or Qufu?
— ．I only want to go to Qingdao．
A. Each B. Either C. Neither D. All
【单选题】
4. — The documentary A Bite Of China II is quite popular around China recently. How do you like it? — ______.
A. I think so B. Pretty good C. It’s my pleasure D. All right
【单选题】
5. There are three English-books on the shelf, but ______ of them is mine.
A. both B. neither C.all D. none
【单选题】
6. When the parents arrived at the hall, the students _______ their projects.
A. have finish B. finished C. had finished D. are finishing
【单选题】
7. This week, the _______ seems to change every day: one day is hot; the next day is cold.
A. time B. weather C. season D. way
【单选题】
8. He never does his work _______ Mary.
A. as careful as B. so careful as C. carefully as D. as carefully as
【单选题】
9. — Can he jump high?
— Yes, he ______. He is a good high jumper.
A. must B. need C. can D. shall
【单选题】
10. The shop _____ at 8:00 a．m．and it ________ for ten hours every day．
A. is open; has opened B. is opened; opens
C. opens; is open D. opened; opens
【单选题】
11. —Excuse me, may I use your bicycle? ______ is broken.
—Certainly. But remember to return it before lunch.
A. Mine B. Me C. Myself D. I
【单选题】
12. —Simon, what do I need to take for the hiking?
—You’d better ________ more water than usual. It’s hot today.
A. to take B. taking C. take D. took
【单选题】
13. Helen ______ to a language school when she was seven.
A. sent B. is sent C. will send D. was sent
【单选题】
14. — Is this park you’ve visited recently?
— Yes, it's the most beautiful one I’ve ever visited before.
A. that B. the one C. which D. the one which
【单选题】
15. — It’s difficult for the village children to cross the river for school.
— I think a bridge ________ over the river.
A. should be built B. is being built C. has been built D. was built
【单选题】
16. — Could you tell me when Mr. Li ________ in Huaibei?
— Sure．．When he ________, I’ll call you．
A. arrives; will arrive B. will arrive; will arrive
C. arrives; arrives D. will arrive; arrives
【单选题】
) 17.There is ________ 800-metre-long road behind ________ hospital．
A. an; an B. an; the C. a; a D. a; the
【单选题】
18. — Did you see a girl in yellow pass by just now?
— No, sir. I ________ a magazine.
A. read B. am reading C. was reading D. would read
【单选题】
19.In fact, my parents are not only kind to me, but also strict ________ me.
A. at B. to C. for D. with
【单选题】
20. The boy_____ a yellow sweater can_____ himself now．
A. wearing; dress B. putting on; wear C. put on; dress D. dressing; wear
【单选题】
21. —Jack, I haven’t seen your brother for a long time．
— He ________Shanghai on business for two months．
A. went to B. has gone to C. has been in D. has been to
【单选题】
22. The meat with eggs tastes ______. Would you like some more?
A. nice B. well C. bad D. wonderfully
【单选题】
23. — Look! The man standing at the gate ______ be our headmaster．
— No, it _______ be him．He is holding a meeting in the office now．
A. must; can’t B. must; mustn’t C. can’t; can’t D. can’t; mustn’t
