【单选题】
10KV/0.4KV电力变压器低压侧中性点应进行工作接地，其接地电阻值应不大于___。
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【单选题】
电气设备保护接地电阻越大,发生故障时漏电设备外壳对地电压___.
【单选题】
电器设备未经验电,一律视为___
A. , 有电,不准用手触及
B. , 无电,可以用手触及
C. , 无危险电压
【单选题】
维修电工在操作中，特别要注意___问题。
A. 戴好安全防护用品
B. 安全事故的防范
C. 安全文明生产行为
【单选题】
人体___是最危险的触电形式。
A. 单相触电
B. 两相触电
C. 跨步电压触电
【单选题】
发生电气火灾后必须进行带电灭火时,应该使用___.
A. , 消防水喷射
B. , 干粉灭火剂
C. ,泡沫灭火器
【单选题】
电压等级低于___伏的电器属于低压电器。
【单选题】
对于照明和电加热负载，熔体的额定电流应为___倍负载额定电流。
【单选题】
控制一台不经常启动的电动机时，熔断器熔体额定电流选为电机额定电流的___倍
【单选题】
控制一台经常启动的电动机时，熔断器熔体额定电流选为电机额定电流的___倍
【单选题】
热继电器中的双金属片弯曲是由于两金属片___
A. 机械强度不同
B. 热膨胀系数不同
C. 温差效应
【单选题】
热继电器中热元件的整定电流应为电动机额定电流的___倍
A. 0.7
B. 0.95～1.05
C. 1.5
【单选题】
控制按钮属于主令电器，它主要接在___。
A. 主回路
B. 控制回路
C. 主回路和控制回路
【单选题】
按钮的触头允许通过的电流较小，一般不超过___安。
【单选题】
下列承担短路保护的电器是___
A. –交流接触器或中间继电器
B. --熔断器
C. —热继电器
【单选题】
下列承担过载保护的电器是___
A. –交流接触器或中间继电器
B. --熔断器
C. —热继电器
【单选题】
下列承担失压保护的电器一般为___
A. –交流接触器或中间继电器
B. --熔断器
C. —热继电器
【单选题】
一台30KW的三相交流电动机其输入的有功功率应该为___
A. 小于30KW
B. 等于30KW
C. 大于30KW
【单选题】
三相交流笼型异步电动机直接启动电流是额定电流的___
【单选题】
三相交流笼型异步电动机的转速同___成正比。
【单选题】
三相交流笼型异步电动机的转矩与___成正比。
【单选题】
三相异步电动机的机械特性曲线是___。
A. T＝f（s）
B. T＝f（n）
C. u＝f（Ｉ）
【单选题】
用摇表检查低压电动机定子绕组间绝缘、绕组对机壳绝缘电阻，其数值不应低于___
【单选题】
三相异步电动机电源接后电机不能起动，造成故障的可能原因是___。
A. 电源电压过高或过低
B. 定子绕组接线错误
C. 鼠龙电动机转子断条
【单选题】
按钮联锁正反转控制线路的优点是操作方便，缺点是容易产生电源两相短路事故。在实际工作中，经常采用___正反转控制线路。
A. 按钮联锁
B. 接触器联锁
C. 按钮、接触器联锁
【单选题】
按钮联锁正反转控制线路的优点是操作方便，缺点是容易产生___事故。
A. 电源两相短路
B. 电源两相断路
C. 停车
【单选题】
三相笼型交流异步电动机功率大于___时一般应采用降压启动。
【单选题】
电磁抱闸制动的优点是此系统是在___。
【单选题】
行车、提升机采用的控制方式是___
A. 启动控制
B. 点动控制
C. 点动-启动混合控制
【单选题】
___简称PLC。
A. 顺序控制器
B. 可编程序控制器
C. 微型计算机
【单选题】
可编程序控制器通过编程，灵活地改变其控制程序相当于改变了继电器控制的___线路。
A. 主回路和控制回路
B. 控制回路
C. 硬接线
【单选题】
可编程控制器的点数是指___。
A. 输入端子个数
B. 输出端子个数
C. 输入端子和输出端子个数的和
【单选题】
可编程控制器输入接口常接的部件有___
【单选题】
可编程控制器输出接口常接的部件有___
【单选题】
可编程控制器小型机的I／O点数是___
A. 64点一下
B. 64～256
C. 256～2048
【单选题】
可编程控制系统同继电器控制系统的主要区别在于___
【单选题】
下面的文字符号___是PLC的输入继电器。
A. --I0.0
B. --C3
C. --M0.3
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A peculiarly pointed chin is his most memorable facial __________.
A. mark
B. feature
C. trace
D. appearance
【单选题】
John Dewey believed that education should be a preparation for life, that a person learns by doing, and that teaching must ________ the curiosity and creativity of children.
A. seek
B. stimulate
C. shape
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【单选题】
Criticism and self-criticism is necessary _______ it helps us to find and correct our mistakes.
A. by that
B. at that
C. on that
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【单选题】
However, at times this balance in nature is ________, resulting in a number of possibly unforeseen effects.
A. troubled
B. disturbed
C. confused
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【单选题】
The patient’s health failed to such an
extent that he was put into _____ care.
A. tense
B. rigid
C. intensive
D. tight
【单选题】
Does everyone on earth have an equal right _________ an equal share of its resources?
A. by
B. at
C. to
D. over
【单选题】
In 1914, an apparently insignificant event in a remote part of Eastern Europe __________ Europe into a great war.
A. inserted
B. imposed
C. pitched
D. plunged
【单选题】
We had to ___________ a lot of noise when the children were at home.
A. go in for
B. hold on to
C. put up with
D. keep pace with
【单选题】
A person's calorie requirements vary ______ his life.___
A. across
B. throughout
C. over
D. within
【单选题】
Generous public funding of basic science would ________considerable benefits for the country's health, wealth and security.___
A. lead to
B. result from
C. lie in
D. settle down
【单选题】
In a time of social reform, people's state of mind tends to keep ___________ with the rapid changes of society___
A. step
B. progress
C. pace
D. touch
【单选题】
The speech which he made __________ the project has bothered me greatly.___
A. regarded
B. concerned
C. regarding
D. concerning
【单选题】
Harry was _______ by a bee when he was collecting the honey.___
A. stung
B. stuck
C. bitten
D. scratched
【单选题】
The thief tried to open the locked door but _________.___
A. in no way
B. in vain
C. without effect
D. at a loss
【单选题】
Remember that customers don't ________ about prices in that city.___
A. debate
B. consult
C. dispute
D. bargain
【单选题】
I hope that you'll be more careful in typing the letter. Don't _________ anything.___
A. lack
B. withdraw
C. omit
D. leak
【单选题】
The tomato juice left brown __________ on the front of my jacket.___
A. spot
B. point
C. track
D. trace
【单选题】
The committee is totally opposed ________ any changes being made in the plans.___
A. of
B. on
C. to
D. against
【单选题】
I'm very sorry to have _______ you with so many questions on such an occasion.___
A. interfered
B. offended
C. impressed
D. bothered
【单选题】
The price of beer _______ from 50 cents to $4 per liter during the summer season.___
A. altered
B. ranged
C. separated
D. differed
【单选题】
Their son doesn't know what to ________ at the university; he can't make up his mind about his future.___
A. take in
B. take up
C. take over
D. take after
【单选题】
Although they plant trees in this area every year, the tops of some hills are still _________.___
A. blank
B. hollow
C. vacant
D. bare
【单选题】
Being a pop star can be quite a hard life, with a lot of traveling ________ heavy schedules.
A. with regard to
B. as to
C. in relation to
D. owing to
【单选题】
Tony is very disappointed _______ the results of the exam.
A. with
B. for
C. toward
D. on
【单选题】
William Penn, the founder of Pennsylvania, _________ defended the right of every citizen to freedom of choice in religion.
A. peculiarly
B. indifferently
C. vigorously
D. inevitably
【单选题】
When people become unemployed, it is _______ which is often worse than lack of wages.___
A. laziness
B. poverty
C. idleness
D. inability
【单选题】
In previous times, then fresh meat was in short __________, pigeons were kept by many households as a source of food.
A. store
B. provision
C. reserve
D. supply
【单选题】
Those gifts of rare books that were given to us were deeply _________.___
A. appreciated
B. approved
C. appealed
D. applied
【单选题】
It is our ___________ policy that we will achieve unity through peaceful means.___
A. consistent
B. continuous
C. considerate
D. continual
【单选题】
He is __________ about his chances of winning a gold medal in the Olympics next year.___
A. optimistic
B. optional
C. outstanding
D. obvious
【单选题】
The director was critical _______________ the way we were doing the work.___
A. at
B. in
C. of
D. with
【单选题】
In a sudden _____________ of anger, the man tore up everything within reach.___
A. attack
B. burst
C. split
D. blast
【单选题】
In Britain people _____________ four million tons of potatoes every year.___
A. swallow
B. dispose
C. consume
D. exhaust
【单选题】
I'd _____________ his reputation with other farmers and business people in the community, and then make a decision about whether or not to approve a loan.___
A. take into account
B. account for
C. make up for
D. make out
【单选题】
She cooked the meat for a long time so as to make it _____________ enough to eat.___
A. mild
B. slight
C. light
D. tender
【单选题】
The computer revolution may well change society as _____________ as did the Industrial Revolution.___
A. certainly
B. insignificantly
C. fundamentally
D. comparatively
【单选题】
A lot of ants are always invading my kitchen. They are a thorough ___________.___
A. nuisance
B. trouble
C. worry
D. anxiety
【单选题】
As we can no longer wait for the delivery of our order, we have to _________ it.___
A. postpone
B. refuse
C. delay
D. cancel
【单选题】
When a fire _________ at the National Exhibition in London, at least ten priceless paintings were completely destroyed.___
A. broke of
B. broke out
C. broke down
D. broke up
【单选题】
The destruction of these treasures was a loss for mankind that no amount of money could __________.___
A. stand up to
B. make up for
C. come up with
D. put up with
