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28.>三相绕线电动机启动方法是在___接入适当的启动电阻,或者串频敏变阻器。
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29.>直流伺服电动机按励磁方式分为他励式和___式二种。
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30.>直流电动机的励磁方式可分为他励、并励、串励和___。
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31.>漏电保护器绝缘电阻不低于___MΩ方可使用。
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32.>拉开隔离开关时应先拉负载侧,后拉母线侧,合上时与拉开时顺序___。
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33.>RL1系列螺旋式熔断器,熔体内部充满___。
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34.>一般情况下,低压电器的动触头应接___。
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35.>一般情况下,低压电器的静触头应接___。
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36.>配线过程中,为防止接头腐蚀,铜线与铝线的连接要采用___。
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37.>日光灯管、温度计中主要含有的有毒化学物质是___。
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38.>变配电所倒闸操作的基本原则是:送电时先合___,再合断路器,停电时顺序相反。
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39.>电感滤波适用于负载电流较___、负载变化大的场合。
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40.>电容滤波适用于负载电流较___、负载稳定的场合。
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41.>电气原理图一般分为___和辅助电路两部分。
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42.>机床电气控制线路中常用的保护环节有短路保护、过载保护、___、联锁保护和限位保护。
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43.>电路中电位的数值是相对值,随参考点而变,而电路中任意两点间的___则与参考点无关。
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44.>若几个同频率的正弦交流电的初相角相同,则称它们___。
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45.>若几个同频率的正弦交流电的初相角相差为180°,就称它们___。
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46.>若几个同频率的正弦交流电初相角既不相同又不相差180°,则初相角大的正弦交流电为___。
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47.>在三相四线制电路中,三相负载愈接近对称,中线电流愈___。
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48.>纯电阻电路中,电压与电流的相位关系是___。
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49.>纯电感电路中,电流和电压的相位关系是___。
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50.>纯电容电路中,电流和电压的相位关系是___。
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51.>正弦交流电路中,总电压的有效值与电流的有效值的乘积通常把它叫做___。
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52.>三相负载接在三相电源上,若各相负载的额定电压等于电源的线电压,应作___连接。
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53.>三相负载接在三相电源上,若各相负载的额定电压等于电源线电压1/3,应作___ 连接。
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54.>两个同频率的正弦量在相位上的差叫___。
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55.>两线圈串联时,若将它们的异名端相联,称为 ___。
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56.>两线圈串联时,若将它们的同名端相联,称为___。
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57.>某电路两端的端电压u=220sin___V,总电流为i=4.4sin___A,则该电路为___电路。
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58.>电机正反转运行中的两接触器必须实现相互间___。
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59.>三相异步电机采用能耗制动时,当切断电源时,将定子绕组送入___电。
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60.>用毫伏表和干电池测量直流电机绕组是否接地时,毫伏表一端导线接到转轴上,另一端导线依次接触各换向片,如果毫伏表指针摆动,则说明该绕组与该绕组相连的换向片___接地故障。
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61.>复杂电路处在过渡过程中时,基尔霍夫定律___。
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62.>动力配电箱中横装的插入式熔断器等应从面对配电盘的左侧接___。
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63.>供用电合同的内容包括供电方式、质量、时间、用电容量、地址、性质、计量方式、电价、电费的结算方式,供用电设施的___责任等条款。
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64.>蜗杆传动机构的装配,首先要保证蜗杆轴线与蜗轮轴心线___。
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65.>台虎钳夹紧工件时,只允许___。
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66.>在变压器中性点直接接地的三相四线制系统中,将其零线的一处或多处接地称为___接地。
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67.>三条或三条以上支路的汇点叫___。
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68.>订立劳动合同,应当遵守合法、___、平等自愿、协商一致、诚实信用原则。
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增强面对新时代新使命,必须在全党营造善于学习、勇于实践的浓厚氛围,建设马克思主义____政党。 ___
A. 人民型
B. 事业型
C. 研究型
D. 学习型
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必须坚持党的( ),既要充分发扬民主,又要善于集中。 ___
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党是最高政治领导力量,是推进伟大事业的( )保证。 ___
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According to one study, what do green spaces do to people? ___
A. Improve their work efficiently.
B. Add to their sustained happiness.
C. Help them build a positive attitude towards life.
D. Lessen their concerns about material well-being.
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What does Dr. White say people usually do to make themselves happier? ___
A. Earn more money.
B. Settle in an urban area.
C. Gain fame and popularity.
D. Live in a green environment.
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What does Dr. White try to find out about living in a greener urban area? ___
A. How it affects different people.
B. How strong its positive effect is.
C. How long its positive effect lasts.
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What did Dr. White’s research reveal about people living in a green environment? ___
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According to Dr. White, what should the government do to build more green spaces in cities? ___
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D. Raise public awareness of the issue.
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The survey by the Kaiser Family Foundation is mentioned to illustrate the idea that . ___
A. kids don’t always follow parents’ rules
B. only few parents believe the good news
C. much media use results in bad health
D. parents’ rules make a huge difference
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What did the kids do when parents set any time or content limits, according to the Kaiser Family Foundation? ___
A. They cut down on their screen time.
B. They appreciated their parents’ love.
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D. They accepted parents’ rules unwillingly.
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What will Kenneth Ginsburg most probably suggest that parents should do? ___
A. Avoid setting firm rules.
B. Avoid ruling with an iron grip.
C. Set rules after family discussion.
D. Set rules that are easy to understand.
【单选题】
Margaret Broe -Fitzpatrick finds it impossible. ___
A. to achieve just- right parenting
B. to keep track of everything done by the kids
C. for the kids to face rules alone
D. for the kids to observe rules without protest
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The passage is mainly intended for parents . ___
A. whose kids have difficulty in self- discipline
B. whose kids are addicted to media use
C. who have doubts about setting rules
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【单选题】
The word “it” (Para. 2) most probably refers to. ___
A. the lack of stable communities
B. the breakdown of informal information channels
C. the increased mobility of families
D. the growing number of people moving from place to place
【单选题】
The main problem people may encounter today arises from the fact that . ___
A. they have to learn new things consciously
B. they lack the confidence of securing reliable and trustworthy information
C. they have difficulty obtaining the needed information readily
D. they can hardly carry out casual communications with an extended family
【单选题】
From the passage we can infer that _______. ___
A. electronic mail will soon play a dominant role in transmitting messages
B. it will become more difficult for people to keep secrets in an information era
C. people will spend less time holding meetings or conferences
D. events will be reported on the spot mainly through satellites
【单选题】
Technology facilitates _______. ___
A. sharing information
B. storing and sending information
C. providing people with easy access to more information
D. all of the above
【单选题】
We can learn from the last paragraph that _______. ___
A. it is necessary to obtain as much
B. people should make the best use of the information
C. we should realize the importance of accumulating information
D. it is of vital importance to acquire needed information efficiently
【单选题】
The author thinks that people are _________. ___
A. satisfied with their appearance
B. concerned about appearance in old age
C. far from neglecting what is in fashion
D. reluctant to follow the trends in fashion
【单选题】
Fashion magazines and TV advertisements seem to link fashion to _________. ___
A. confidence in life
B. personal dress
C. individual hair style
D. personal future
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Causes of fashions are _________. ___
A. uniform
B. varied
C. unknown
D. inexplicable
【单选题】
Present-day society is much freer and easier because it emphasizes _________. ___
A. uniformity
B. formality
C. informality
D. individuality
【单选题】
Which is the main idea of the last paragraph? ______________ ___
A. Care about appearance in formal situations.
B. Fashion in formal and informal situations.
C. Ignoring appearance in informal situations.
D. Ignoring appearance in all situations.
【单选题】
Permissive parents would ________. ___
A. let their children read any books they like to
B. not let their children see any films they like to
C. not let their children read any books without first checking their contents
D. let their children see the films with their first checking
【单选题】
The fact that parents check the contents of the book or the film for their children to read or see shows __________. ___
A. the necessity of censorship
B. that many books and films are bad
C. that children need their parents to help them understand more
D. that the parents are permissive
【单选题】
Which of the following statements is NOT true?____________ ___
A. Some adults can’t tell right from wrong.
B. Censorship is compared to the law because both of them perform good service to society as a whole.
C. Censors pay attention only to genuine works of art.
D. Censorship is necessary because many books, plays and films are far from being “works of art”.
【单选题】
What does the word “corrupt” in Para.4 mean?__________ ___
A. Make morally bad.
B. Hurt.
C. Injure.
D. Damage.
【单选题】
What would be the best title of this passage?_____________ ___
A. Permissive Parents and Responsible Parents.
B. Censorship and the Law.
C. Censors Value Artistic Merits .
D. Censorship Performs Good Service to Society.
【单选题】
Lie detectors are widely used in the United States because _____________. ___
A. they can help detect people’s emotional stress
B. they can help detect people's physiological changes
C. they can help find out whether a person is telling the truth or not
D. they can measure the subject’s electrical resistance
【单选题】
According to the passage, we know that Britain______________. ___
A. will adopt lie detectors widely
B. will adopt lie detectors on a smaller scale
C. adopt lie detectors
D. has not decided whether to adopt lie detectors or not
【单选题】
The tests themselves are by no means free from error..." (Line 1-2.Para.3) means ____________. ___
A. the tests definitely have no error
B. the tests sometimes make mistakes
C. the polygraphers do not make mistakes
D. the polygraphers can avoid error by using some techniques
【单选题】
Which of the following is true? ________________ ___
A. The tests are conducted by qualified polygraphers.
B. Innocent people may blush or stammer when questioned.
C. Guilty people can definitely be found out by answer questions
D. Guilty people may escape by refusing to answer questions.
【单选题】
What troubles lie detector researchers most is that _______________. ___
A. innocent people are convicted crimes
B. innocent people will learn to tell lies
C. lie detectors may cause industrial unrests
D. lie detectors are sometimes not dependable
【单选题】
In the passage the author's attitude towards "mixed-ability teaching" is _______. ___
A. critical
B. questioning
C. approving
D. objective
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By "held back" (Line 1) the author means _____. ___
A. made to remain in the same classes
B. forced to study in the lower classes
C. drawn to their studies
D. prevented from advancing
【单选题】
The author argues that a teacher's chief concern should be the development of the student's _________. ___
A. personal qualities and social skills
B. total personality
C. learning ability and communicative skills
D. intellectual ability
【单选题】
Which of the following is NOT MENTIONED in the third paragraph? __________ ___
A. Group work gives pupils the opportunity to learn to work together with others.
B. Pupils also learn to develop their reasoning abilities.
C. Group work provides pupils with the opportunity to learn to be capable organizers.
D. Pupils also learn how to participate in teaching activities.
【单选题】
The author's purpose in writing this passage is to ______. ___
A. argue for teaching bright and not-so-bright pupils in the same class
B. recommend pair work and group work for classroom activities
C. offer advice on the proper use of the library
D. emphasize the importance of appropriate formal classroom teaching
【单选题】
According to the author, the deaths among youth are mainly caused by _____. ___
A. traffic accidents
B. smoking-related diseases
C. murder
D. all of these
【单选题】
Every day there are over_____high school students who will become regular smoker. ___
A. 75
B. 23
C. 30
D. 3000
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