相关试题
【判断题】
常用安全电压为：36,24,12伏三种。
【判断题】
容量在2千伏安以下的单相变压器称为小型变压器。
【填空题】
1、欧姆定律表明，电路中电阻不变时电流与___成正比，电路中电压不变时电流与___成反比。
【填空题】
2、R1、R2、R3三个电组串联后接到电压为U的电源上，则该电路的总电流为___)。
【填空题】
3、某直流负载两端电压为12V，其电流为8A，该负载电阻为___。
【填空题】
4、220V、100W的电烙铁其电阻应为___。
【填空题】
5、一条电阻值为80Ω的电阻丝，对折后并联测量，其电阻值应为___。
【填空题】
6、我国电力系统中，交流电的频率为___ ，周期为___。
【填空题】
8、正弦交流电的频率为50HZ，则角频率为___。
【填空题】
9、正弦交流电的最大值是311V，其有效值为___。
【填空题】
10、有一单相正弦电压u=311sin___V，其最大值为___，初相位为___。
【填空题】
11、R=6Ω的纯电阻与Xc=8Ω的纯容抗相串联，其等效阻抗为___。
【填空题】
12、R=9Ω的纯电阻与XL=8Ω的纯___抗相串联，其等效阻抗为___。
【填空题】
13、三相交流电为了区别相位，用统一规定的颜色来表示，我国规定用黄色表示A相，用___色表示B相，用___表示C相。
【填空题】
14、在交流电路中，电源提供的电功率有两种：一种是___功率，另一种是有功功率。
【填空题】
15、测量电流应使用___，并将其___在电路中。
【填空题】
16、为保证测量的准确，电流表的内阻应尽可能地___。
【填空题】
17、为保证测量的准确，电压表的内阻应尽可能地___。
【填空题】
18、测量线路中的电流，但又不能中断负载的运行，应选用___的电流表。
【填空题】
19、万用表用毕，应将转换开关拨至交直流___或OFF档。
【填空题】
20、通过人体工频电流的有效值约为___时，会有触电的感觉，此值称为___电流。
【填空题】
21、通过人体工频电流的有效值约为___时，触电者能自主地摆脱电源，此值称为___电流。
【填空题】
22、通过人体工频电流的有效值达到___时，有可能引起心室纤维颤动，这是___的主要原因。
【填空题】
23、触电事故发生的季节性表现在：___季比___季多，以___月份为最多。
【填空题】
24、保护接地适用于电源中性点___的三相三线配电网。
【填空题】
25、常用的低压基本安全用具有___。
【填空题】
26、低压电器是指工作在额定电压___及以下电路中的电器。
【填空题】
27、电力系统中一般以大地为参考点，把电路的任一点接地，则该点的电位就是___电位。
【填空题】
28、配电变压器二次侧中性点接地的性质为___。
【填空题】
29、中性点直接接地的低压供电系统中的零线上___装设开关和熔断器。
【填空题】
30、测量电能的仪表称为___或电能表，它的计量单位是___。
【填空题】
31、___是一种专门用来测量绝缘电阻的便携式仪表。
【填空题】
32、供电电能的质量指标主要有：频率、___、波形。
【填空题】
33、变压器的基本功能是改变交流___。
【填空题】
34、变压器一次电压与二次电压之比等于___和 ___之比。
【填空题】
35、对继电器保护装置的基本要求是：选择性、___、可靠性、灵敏性。
【填空题】
36、安全工作规程是中规定：设备对地电压高于 ___ 为高电压；在 ___ 以下为低电压；安全电压为___以下；安全电流为___以下。
【填空题】
37、值班人员因工作需要移开遮栏进行工作，要求的安全距离是 10k Ｖ时 ___ m ,35k Ｖ时 ___ m ，110k Ｖ时 ___ m ,220k Ｖ时 ___ m 。
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
