相关试题
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发展经济学成为一门独立科学是从1970年代开始的。
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发展主义是由发达国家经济学家提出的一种理论。
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结构主义学派特别强调资本形成在经济起飞或经济增长中的作用。
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购买力评价理论是由联合国开发计划署提出的。
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>三相异步电动机的变极调速只能用在笼型转子电动机上
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>普通电风扇上的单相电动机一般采用串电抗的方法调速
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>画零件草图和装配图后，绘制零件工作图，然后再以零件图绘制装配图的目的是在图纸上进行一次装配
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>在安装功率表时，必须保证电流线圈与负载相串联，而电压线圈与负载相并联
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>三相异步电动机的变极调速只能用在笼型转子电动机上
【判断题】
>普通电风扇上的单相电动机一般采用串电抗的方法调速
【判断题】
>画零件草图和装配图后，绘制零件工作图，然后再以零件图绘制装配图的目的是在图纸上进行一次装配
【判断题】
>在安装功率表时，必须保证电流线圈与负载相串联，而电压线圈与负载相并联
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>步进电动机步距(或转速)不受电压波动和负载变化的影响，而只与脉冲频率成正比，它能按控制脉冲数的要求，立即启动、停止和反转
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>当单相桥式整流电路中任一整流二极管发生短路时，输出电压的数值将下降一半，电路变成半波整流电路
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>编程时每个逻辑行上，串联触点多的电路应排在上面
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>可编程序控制器使用的十进制常数用K表示
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>可编程序控制器的输出继电器的全部接点都可以作输出控制用
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>变频器主电路由整流及滤波电路、逆变电路和制动单元组成
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>变频器与电动机之间不可连接控制电动机启动停止的开关，以免造成变频器空开跳闸及损坏
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>变频器输入控制端子分为数字量端子和模拟量端子
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>运行中的电流互感器若副边电流表损坏时，可直接拆下损坏仪表，然后换上新的电流表
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>基尔霍夫定律适用于直流电路，也适用于交流电路，对于含有电子元件的非线性电路也适用
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>在感性负载两端并联适当的电容器后，可使通过感性负载的电流量减小，使电路的功率因数得到改善
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>接收程序控制与存储程序控制都是硬件控制
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>选择接触器时，只要满足触头容量就可以了
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>在交流与直流接触器中，铁芯都是用来导磁的，所以二者的铁芯可以通用
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>在安装电流互感器时，铁芯和副边要同时可靠的接地
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>选择锉刀尺寸规格，取决于加工余量的大小
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>零件拆卸时，拆卸前应先量得一些主要装配尺寸和校验一些主要精度
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>漏电保护器不应装在高温、振动、粉尘等场所
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>劳动者违反竞业限制约定的，应当按照约定向用人单位支付违约金
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>变压器是一种利用电磁感应的原理，将某一数值的交流电压转变为频率相同的另一种或两种以上的交流电压的电气设备
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>多速异步电动机的结构和一般异步电动机相似，不同的是定子绕组的接线，试车前一定要检查接线是否正确
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>只要三相定子绕组每相都通入交流电流，便可产生定子旋转磁场
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>异步电动机的调速方法主要有以下几种：依靠改变定子绕组的极对数调速、改变转子电路的电阻调速、变频调速和串级调速等
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>单相异步电动机的体积虽然较同容量的三相异步电动机大，但功率因数、效率和过载能力都比同容量的三相异步电动机低
【判断题】
>交流伺服电动机的工作原理和单相电容式异步电动机相同
推荐试题
【单选题】
Tom is a book lover. ______ likes reading very much.
A. He B. She C. You D. It
【单选题】
—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
【单选题】
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
【单选题】
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
【单选题】
5. I was looking for a birthday gift for my mother, but I couldnt find ______ suitable.
A. anything B. something C. nothing D. everything
【单选题】
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
【单选题】
7. She ______ very hard since she came to our school.
A. studies B. has studied C. is studying D. studied
【单选题】
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
【单选题】
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
【单选题】
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
【单选题】
11. How do you like the dishes, Eric?
— Fantastic! Nothing tastes ________.
A. nice B. better C. terrible D. worse
【单选题】
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
【单选题】
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
【单选题】
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
【单选题】
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
【单选题】
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
【单选题】
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
【单选题】
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
【单选题】
23. It was dark, ______ I couldnt see what was happening.
A. or B. though C. but D. so
【单选题】
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
【单选题】
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
