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电器是应电能的运用而产生的，所以电机和一般的负载属于电器的范畴。
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相关试题
【判断题】
电器工作时，发热和散热不同时存在于电器发热过程中。
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电磁驱动装置是把电能转换为磁能的机构。
【判断题】
对电网来说三相异步电动机是一个电感负载。
【判断题】
电器工作时，发热和散热不同时存在于电器发热过程中。
【判断题】
电弧属于气体放电的一种形式，气体放电分为自持放电与非自持放电两类。
【判断题】
电器触头驱动装置有三种：电驱动、手动、磁驱动。
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触头对电器的工作性能、总体结构、尺寸有着决定性的影响。
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触头的参数主要有触头的结构尺寸、开距、超程、研距、触头初压力等。
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触头闭合后，其接触处有一定的互压力，称为触头压力。
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电阻制动是将牵引电机发出的电能转化为热能而消耗掉。
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不同的电路应使用不同电压等级的兆欧表来测量其绝缘电阻。
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在电子电路中要形成谐振电路，必须有电感和电容两种类型的元件。
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三相不对称负载做△接法，其线电压将不对称。
【判断题】
TQG3A型电压传感器利用霍尔效应，采用磁补偿原理，通过霍尔元件实现对直流、交流及脉动电流的电隔离测量，输出信号反比于被测电流。
【判断题】
机车使用串励牵引电机是因为串励电机的特性比较硬，不易空转。
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机车换向是通过改变牵引电机端电压极性来实现的。
【判断题】
SS4型电力机车牵引电机采用串励供电方式。
【判断题】
电力机车进行电阻制动时，牵引电机呈他励励磁方式。
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93·为适应高速列车运行需要，异步牵引电动机大多采用半悬挂方式(或称架承式悬挂)。
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三相异步电动机变极调速就是改变定子绕组的极对数来调速。
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SS4型电力机车牵引电机仅采用调压调速。
【判断题】
牵引电机的磁场削弱是为了提高机车的速度。
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牵引电机励磁绕组中的电流降至零，磁极中就不存在磁场。
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直流电机改善换向的工作原理是使附加电流减小或等于零。
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直流电机中任一电枢元件中流通的电流方向是始终不变的。
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直流电动机调压调速是恒转速调速，弱磁调速是恒功率调速。
【判断题】
电机温升试验的目的是检查电枢绕组、定子绕组、换向器和轴承的发热情况。
【判断题】
为了防止环火的发生，牵引电动机最有效的措施是设置补偿绕组。
【判断题】
SS7型电力机车上电机励磁绕组由串励、自励组成。
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Tom is a book lover. ______ likes reading very much.
A. He B. She C. You D. It
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—May I listen to the music here, Mr. White?
—Sorry, you’d better it like that．
A. not to do B. not do to
C. dont do D. not do
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3.—Did you have a good time at Lauras birthday party?
— Yes, indeed. Its several years ________ I enjoyed myself so much.
A. when B. before C. since D. that
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4. —___________ is the Summer Palace from here?
About three kilometers away. You can take the No. 35 bus.
A. How long B. How far C. How often D. How much
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5. I was looking for a birthday gift for my mother, but I couldnt find ______ suitable.
A. anything B. something C. nothing D. everything
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6. A friend of my ____ and I are going to visit_______ next week．
A. father; Browns B. father's; Browns
C. father; the Browns D. father's; the Browns
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7. She ______ very hard since she came to our school.
A. studies B. has studied C. is studying D. studied
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8. — Who will send you to the new school, your mom or your dad?
— _______. Ill go there by myself.
A. Both B. Either C. Neither D. None
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9.—Well do what we can ____English well this term．
—It’s high time for you to work hard．
A. study B．to study C. be studied D. be studying
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10. —I’m going to Flower Bookstore. Could you tell me ______?
— Sorry, I don’t know. I’m new here.
A. where it is B. where was it C. where is it D. where it was
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11. How do you like the dishes, Eric?
— Fantastic! Nothing tastes ________.
A. nice B. better C. terrible D. worse
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12. ______ Lin Feng has to work late, she always wears a smile on her face.
A. Because B. If C. Until D. Though
【单选题】
13.You can save money _______ you buy cheaper things.
A. before B. unless C. if D. until
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14. We will have a _________ holiday after the exam．
A. two-month B. two month’s C. two month D. two-months
【单选题】
15. —We will build an underground in Xuzhou before 2015．
— Wow, _______! Will it pass our place?
A. what an excited news B. how excited the news is
C. what exciting news D. how exciting
【单选题】
16. — Emily, here’s a dictionary．I hope it will help you in some way．
— Thank you．It’s ________ what I need．
A. almost B. still C. only D. just
【单选题】
17. —Oh．I’m hungry．Mum, can I have the hamburger on the plate?
—No．It tastes ．
A. terribly B. terrible C. good D. well
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18. —We can invite our teachers to the farewell party next Saturday.
—Yes, ______? I’ll call them at once.
A. what for B. what C. why not D. why
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19.You can ________ ask the old man to move away to any other place because he has lived ________ here for at least sixty years．
A. hardly; alone B. hard; alone
C. hardly; lonely D. hardly; lonely
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20.—I’m going back to see my grandparents this weekend．
—________．
A. It’s very nice of you B. You’d better hurry
C. Say goodbye to them D. Give my best wishes to them
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21.—Why not take ____ umbrella with the sign “Made in China”? It is useful.
—What _______ good advice it is!
A. an; a B. a; a C. an; \ D. \; a
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22. —Do you know the boy________ is sitting next to Peter?
— Yes. He is Peter’s friend. They are celebrating his ________ birthday.
A. who; ninth B. that; ninth C. /; ninth D. which; ninth
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23. It was dark, ______ I couldnt see what was happening.
A. or B. though C. but D. so
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24.—You can use MSN to talk with Vivien on the Internet.
—I know. But can you tell me ________?
A. what I can use it B. when I can use it
C. why can I use it D. how can I use it
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25. _______ are you going to the School Uniform Exhibition, Amy ?
To learn about different styles of school uniform.
A. What B. Where C. Which D. Why
【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 prince
【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．
【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．
【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．
【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
【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.
【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
【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.
【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.
【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
