相关试题
【单选题】
在 ___ 中,电动势、电压、电流的大小和方向随时间按正弦规律变化。
A. 直流电路
B. 正弦交流电路
C. 脉冲电路
【单选题】
在感性负载交流电路中,采用 ___ 的方法可提高电路功率因数。
【单选题】
流过导体单位截面积的电流叫电流密度,其单位为 ___ 。
A. 安培
B. 安培/ 平方米
C. 安培/ 平方毫米
【单选题】
电气设备有三种工作状态,即运行、 ___ 、检修状态。
【单选题】
手车式开关柜,小车已推入 ,开关合入 ,称之为 ___ 。
【单选题】
变压器可以在绝缘及寿命不受影响的前提下,在负载高峰及冬季时可___ 过负载运行。
【单选题】
关于 380/220V 市电系统 ,___ 说法是正确的。
A. 220V 是相电压 ,380V 是线电压
B. 220V 是线电压 ,380V 是相电压
C. 220V 和 380V 都是相电压
【单选题】
通电直导体在磁场中所受力的大小,与其通过的电流___ 。
【单选题】
在 ___ 中,电动势、电压、电流的大小和方向都不随时间的改变而变化。
A. 直流电路
B. 脉动直流电路
C. 脉冲电路
【单选题】
规定在磁体外部,磁力线的方向是___ 。
A. 由 S 极到达 N 极
B. 由 N 极到达 S 极
C. 由 N 极出发到无穷远处
【单选题】
避雷线在防雷保护中所起的作用是___。
A. 防感应雷
B. 防高压雷电波
C. 防直击雷
【单选题】
运行值班人员在室外进行巡回检查,如高压设备发生接地时,不得接近故障点___ 以内。
【单选题】
电气设备由一种工作状态转换到另一种工作状态,或改变电气一次系统运行方式所进行的操作称为___ 。
【单选题】
高压熔断器可用于___ 等设备的保护。
【单选题】
负荷开关与熔断器配合使用时,由熔断器起 ___ 作用。
A. 切断正常负荷电流
B. 短路保护
C. 倒闸操作
【单选题】
___ 指正常情况下没有断开的备用电源或备用设备,而是工作在分段母线状态,靠分段断路器取得相互备用。
【单选题】
下列 ___ 表示 I 段电压小母线A 相。
【单选题】
作用于人体的电压升高,人体电阻还会 ___, 致使电流更大,对人体的伤害更严重。
【单选题】
人体触电可分为直接接触触电和___两大类。
A. 跨步电压触电
B. 接触电压触电
C. 间接接触触电
【单选题】
当人体电阻一定时,作用于人体的电压越高,流过人体的电流___ 。
【单选题】
人体触电后能够自主摆脱的电流称为___。
【单选题】
额定容量是指:在变压器铭牌所规定的额定状态下,变压器二次侧的输出能力___ 。
【单选题】
变压器 ___通常分为无励磁调压和有载调压两种方式。
【单选题】
根据变压器的工作原理,常采用改变变压器___ 的办法即可达到调压的目的。
【单选题】
电力线路按架设方式可分为___ 。
A. 输电线路和配电线路
B. 高压线路和低压线路
C. 架空电力线路和电力电缆线路
【单选题】
三相系统中发生的短路有4 种基本类型 ,三相短路、 ___、单相接地短路和两相接地短路。
【单选题】
电路处于断路状态时,电路中没有 ___ 流过。
【单选题】
已知一部分电路的端电压为10V,电阻为 5？,则电流的电流为___A 。
【单选题】
在纯电阻电路中,电流和电压 ___ 。
A. 同相位
B. 反相位
C. 相位差为π /2
【单选题】
在实际应用中,常用 ___定为设备的额定容量,并标在铭牌上。
A. 有功功率P
B. 无功功率Q
C. 视在功率S
【单选题】
在三相交流电路中,负载消耗的总有功功率等于___ 。
A. 各相有功功率之差
B. 各相有功功率之和
C. 各相视在功率之差
【单选题】
全电路欧姆定律表明,在闭合回路中,电流的大小与电源电动势___, 与整个电路的电阻成反比。
【单选题】
下列关于保护变压器的角型间隙安装位置描述正确的是___ 。
A. 远离变压器一侧
B. 高压熔断器的外侧
C. 高压熔断器的内侧
【单选题】
金属氧化锌避雷器特点有动作迅速、___ 、残压低、通流量大。
【单选题】
线路验电应逐相进行。同杆架设的多层电力线路验电时,先验低压后验高压、___。
A. 先验上层后验下层
B. 验下层
C. 先验下层后验上层
【单选题】
如果在交接班过程中,有异常情况要处理,仍由 ___ 负责处理 ,必要时可请接班人员协助工作。
【单选题】
RN2 型高压熔断器可适用于作___的保护。
推荐试题
【填空题】
49.利用潮水涨落产生的水位差所具有的势能来发电的方法是___。
【填空题】
50.___基础是指桩，墩，沉井，沉箱和地下连续墙等基础。
【填空题】
51.按桩的施工方法，桩分为___和___两类。
【填空题】
52.即可用作深基坑的支护结构，又可作为深基坑的支护和建筑物地下室外墙的是___。
【填空题】
53.砌筑用脚手架是砌筑过程中堆放材料和工人进行操作的___。
【填空题】
54.混凝土浇筑包括___和___两个过程。
【填空题】
55.无粘结预应力混凝土结构在张拉后容许预应力筋对周围混凝土发生___滑动。
【填空题】
56.斜拉桥是新型的桥梁形式，这种形式大桥的主桥分为___和___两大部分。
【填空题】
57.___和___是国际通行的工程建设项目组织实施方式。
【填空题】
58.BIM 中的图形是赋予了___属性的实体。
【填空题】
59.BIM 是指建筑物在设计和建造过程中，创建和使用的“___”。
【单选题】
The word "wag" (Line 1, Para.1) most probably means _________.
A. move
B. shake
C. bite
D. play
【单选题】
The video cameras were used to catch the dogs' responses because ___________.
A. the dogs were put in the wooden boxes
and tested one at a time
B. it was easier to catch the dogs’s response changes in the tail wagging
C. they enabled the dogs’owners to know
about their dogs’; habit
D. the dogs wagged their tails in different
directions when they were in different
moods
【单选题】
When there are no stimuli, a dog will ___________.___
A. wag to the right
B. no wag at all
C. wag to the left
D. wag to the left and then wag to the right
【单选题】
The purpose of doing the experiment is _________.___
A. to train dogs for their owners
B. to help dogs find companion
C. to help people choose their pet dogs
D. to help people judge the mood of dogs
【单选题】
The underlined word "they" in the last sentence refers to __________.___
A. the trainers
B. the systems
C. the researchers
D. the dogs
【单选题】
The new law passed in Rome will ________.___
A. help improve fishing environment
B. stop people from catching goldfish
C. guarantee better conditions for goldfish
D. discourage keeping goldfish at home
【单选题】
People in Rome believe that the civilization of a city can be judged by _________.___
A. awareness of animal protection
B. exchanges with other cities
C. protection of ancient ruins
D. recognition of animal lovers
【单选题】
The underlined word "compassion" in Para 2 is the closest in meaning to __________.___
A. support
B. pity
C. help
D. love
【单选题】
People may break the law in Turin if they ________.___
A. keep their dogs or cats in cars
B. shut their dogs home all day long
C. raise their cats near ancient ruins
D. feed homeless animals in car parks
【单选题】
We can infer from the passage that _________.___
A. the owners can leave their dogs in hot cars
B. the cat only lives in modern life
C. the new law can prevent cruelty to animals
D. the new law gives recognition to the
people who feed homeless cat
【单选题】
If a person finds getting up early a problem, most probably ________.___
A. he is a lazy person
B. he refuses to follow his own energy cycle
C. he is not sure when his energy is low
D. he is at his peak in the afternoon or evening
【单选题】
Which of the following may lead to family quarrels according to the passage?___
A. Unawareness of energy cycles.
B. Familiar monologues.
C. A change in a family member's energy cycle.
D. Attempts to control the energy cycle of other family members.
【单选题】
If one wants to work efficiently at his low point in the morning, he should __________.___
A. change his energy cycle
B. overcome his laziness
C. get up earlier than usual
D. go to bed earlier
【单选题】
You are advised to rise with a yawn and stretch because it will __________.___
A. help to keep your energy for the day's work
B. help you to control your temper early in the day
C. enable you to concentrate on your routine work
D. keep your energy cycle under control all day
【单选题】
Which of the following statements is NOT true?___
A. Getting off to work with a minimum effort helps save one's energy.
B. Dr. Kletman explains why people reach their peaks at different hours of day.
C. Habit helps a person adapt to his own energy cycle.
D. Children have energy cycles, too.
【单选题】
An effective way to prevent the burnout of young athletes is __________.___
A. to increase their sense of success
B. to make sports less competitive
C. to reduce their mental stress
D. to make sports more challenging
【单选题】
According to the passage sport is positive for young people in that __________.___
A. it can help them learn more about society
B. it enables them to find flaws in themselves
C. it teaches them how to set realistic goals for themselves
D. it can provide them with valuable experiences
【单选题】
Many coaches and parents are in the habit of criticizing young athletes __________.___
A. without realizing criticism may destroy their self-confidence
B. in order to make them remember life's lessons
C. believing that criticism is beneficial for their early development
D. so as to put more pressure on them
【单选题】
According to the passage parents and coaches should __________.___
A. help children to win every game
B. pay more attention to letting children enjoy sports
C. train children to cope with stress
D. enable children to understand the positive aspect of sports
【单选题】
The author's purpose in writing the passage is _________.___
A. to persuade young children not to worry about criticism
B. to stress the importance of positive reinforcement to children
C. to discuss the skill of combining criticism with encouragement
D. to teach young athletes how to avoid burnout
【单选题】
As pointed out at the beginning of the passage, people used to think that air pollution _______.___
A. cause widespread damage in the countryside
B. affected the entire eastern half of the United States
C. had damaged effect on health
D. existed merely in urban and industries areas
【单选题】
As to the greenhouse effect, the author ________.___
A. share the same view with the scientist
B. is uncertain of its occurrence
C. rejects it as being ungrounded
D. thinks that it will destroy the world soon
【单选题】
The underlined word "offset" in the second paragraph could be replaced by _________.___
A. slip into
B. make up for
C. set up
D. catch up with
【单选题】
It can be concluded that ____________.___
A. raising the world's temperature only a few degrees would not do much harm to life on earth
B. lowering the world's temperature merely a few degrees would lead major farming areas to disaster
C. almost no temperature variations have occurred over the past decade
D. the world's temperature will remain constant in the years to come
【单选题】
This passage is primarily about __________.___
A. the greenhouse effect
B. the burning of fossil fuels
C. the potential effect of air pollution
D. the likelihood of a new ice age
【单选题】
What is the major function of paragraph 1?___
A. To arouse the reader's concern.
B. To introduce the theme of the whole passage.
C. To summarize the whole passage.
D. To state the primary uses of TV.
【单选题】
Television, as a source of entertainment, is ________.___
A. not very convenient
B. very expensive
C. quite dangerous
D. relatively cheap
【单选题】
Why are some people against TV?___
A. Because TV programs are not interesting.
B. Because TV viewers are totally passive.
C. Because TV prices are very high.
D. Because TV has both advantages and disadvantages.
【单选题】
One of the most obvious advantages of TV is that _________.___
A. it keeps us informed
B. it is very cheap
C. it enables us to have a rest
D. it controls our lives
