交流接触器的检修主要内容有( )。A、触头系统的检修:1)检查三相触头分断是否一致,

题型:多项选择题

问题:

交流接触器的检修主要内容有( )。

A、触头系统的检修:1)检查三相触头分断是否一致,应保证三相触头的不同时接触的偏差,不大于0.5mm。2)测量相间绝缘电阻,绝缘电阻值不应低于10MΩ。3)触头磨损超过厚度1/3、严重灼伤及开焊脱落时,应更换新件;

B、电磁线圈检修:1)对线圈的动作与释放电压要进行试验,要求动作电压为额定电压的80%~105%,释放电压应低于额定电压的40%。2)检查线圈有无过热、变色,要求运行温度不能超过60℃。线圈过热是由于存在匝间短路造成的,测量线圈直流电阻与原始记录进行比较,即可判定。3)检查引线与插件是否有开焊或断开。4)检查线圈骨架有无断裂;

C、取下灭弧罩,用毛刷清除罩内脱落物及金属粒。如发现灭弧罩有裂损,应更换新品。对于栅片灭弧罩,应注意栅片是否完整或烧伤变形,严重脱位变化等应及时更换;

D、保护系统检修:主要看跳闸装置是否可靠动作。

考点:农网配电营业工考试农网配电营业工高级工农网配电营业工高级工题库
题型:多项选择题
已知
cos2x
2
cos(x+
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4
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1
5
,0<x<π,则tanx为(  )
A.-
4
3
B.-
3
4
C.2D.-2
题型:多项选择题

2013年10月18日,纽约商品交易所黄金和白银的期货价格分别收于每盎司1251.75美元和每盎司20.23美元,黄金价格是白银价格的60多倍。这表明

A.期货市场上的黄金和白银是商品

B.黄金的价值量是白银的60多倍

C.货币的本质是一般等价物

D.生产黄金的社会劳动生产率低于白银

题型:多项选择题

阅读理解。

     In bringing up children, every parent watches eagerly the child's acquisition (学会) of each new skill-the

first spoken words, the first independent steps, or the beginning of reading and writing. It is often tempting

to hurry the child beyond his natural learning rate, but this can set up dangerous feelings of failure and states

of worry in the child. This might happen at any stage. A baby might be forced to use a toilet too early, a young

child might be encouraged to learn to read before he knows the meaning of the words he reads. On the other

hand, though, if a child is left alone too much, or without any learning opportunities, he loses his natural

enthusiasm for life and his desire to find out new things for himself.

     Parents vary greatly in their degree of strictness towards their children. Some may be especially strict in

money matters, others are sever over times of coming home at night or punctuality for meals. In general, the

controls imposed represent the needs of the parents and the values of the community as much as the child's

own happiness.

     As regards the development of moral standards in the growing child, consistency is very important in

parental teaching. To forbid a thing one day and excuse it the next is no foundation for morality (道德). Also,

parents should realize that "example is better than precept". If they are not sincere and do not practice what

they preach (说教), their children may grow confused and emotionally insecure when they grow old enough

to think for themselves, and realize they have been to some extent fooled. A sudden awareness of a marked

difference between their parents' principles and their morals can be a dangerous disappointment.

1. Eagerly watching the child's acquisition of new skills _____.

A. should be avoided

B. is universal among parents

C. sets up dangerous states of worry in the child

D. will make him lose interest in learning new things

2. When children are learning new skills, parents should _____.

A. achieve a balance between pushing them too hard and leaving them on their own

B. not expect too much of them

C. encourage them to read before they know the meaning of the words they read

D. create as many learning opportunities as possible

3. The second paragraph mainly tells us that _____.

A. parental restrictions vary, and are not always for the benefit of the children alone

B. parental controls reflect only the needs of the parents and the values of the community

C. parents should be strict with their children

D. it's parents'and society's duty to control the children

4. The word "precept" in Paragraph 3 probably means "_____".

A. idea

B. punishment

C. instruction

D. behaviour

5. In moral matters, parents should _____.

A. satisfy their children's needs

B. be aware of the marked difference between adults and children

C. forbid things which have no foundation in morality

D. observe (遵守,奉行) the rules themselves

题型:多项选择题

所有非周期信号都是能量信号。

题型:多项选择题

洗胃法的目标是什么?

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