【单选题】
晶体管毫伏表专用输入电缆线，其屏蔽层、线芯分别是___。
A. 信号线、接地线
B. 接地线、信号线
C. 保护线、信号线
D. 保护线、接地线
查看试卷，进入试卷练习
微信扫一扫，开始刷题
相关试题
【单选题】
一般TTL与非门电路的扇出系数通常为___以上。
【单选题】
集成运放的输出级通常由___构成。
A. 互补对称射极放大电路
B. 共射放大电路
C. 共基极放大电路
D. 共集电极放大电路
【单选题】
固定偏置共射极放大电路，已知RB=300KΩ，RC=4KΩ，Vcc=12V，β=50，则UCEQ为 ___V 。
【单选题】
分压式偏置共射放大电路，当温度升高时，其静态值IBQ会___。
A. 无法确定
B. 增大
C. 变小
D. 不变
【单选题】
共射极放大电路的输出电阻比共基极放大电路的输出电阻是___。
【单选题】
能用于传递交流信号且具有阻抗匹配的耦合方式是___。
A. 阻容耦合
B. 变压器耦合
C. 电感耦合
D. 直接耦合
【单选题】
差动放大电路能放大___。
A. 差模信号
B. 直流信号
C. 交流信号
D. 共模信号
【单选题】
下列集成运放的应用能将矩形波变为尖顶脉冲波的是___。
A. 比例应用
B. 加法应用
C. 微分应用
D. 比较器
【单选题】
音频集成功率放大器的电源电压一般为___伏。
【单选题】
RC选频振荡电路，当电路发生谐振时，选频电路的相位移为___度。
【单选题】
LC选频振荡电路，当电路频率高于谐振频率时，电路性质为___。
A. 容性
B. 感性
C. 电阻性
D. 纯电容性
【单选题】
串联型稳压电路的调整管工作在___状态。
A. 放大
B. 截止
C. 饱和
D. 截止与饱和交替
【单选题】
CW7806的输出电压、最大输出电流为___伏。
A. 6V、0.5A
B. 6V、1A
C. 6V、1.5A
D. 6V、0.1A
【单选题】
单相半波可控整流电路中晶闸管所承受的最高电压是___。
A. 1.414 U2
B. U2
C. 0.707 U2
D. 2 U2
【单选题】
单相桥式可控整流电路电感性负载时，控制角α的移相范围是___。
A. 0～90°
B. 0～360°
C. 0～180°
D. 0～270°
【单选题】
单相桥式可控整流电路电阻性负载，晶闸管中的电流平均值是负载的___倍。
【单选题】
___触发电路输出尖脉冲。
A. 交流变频
B. 脉冲变压器
C. 集成
D. 单结晶体管
【单选题】
晶闸管两端并联压敏电阻的目的是实现___。
A. 过压保护
B. 过流保护
C. 防止冲击电流
D. 防止冲击电压
【单选题】
熔断器的额定分断能力必须大于电路中可能出现的最大___。
A. 过载电流
B. 启动电流
C. 工作电流
D. 短路电流
【单选题】
断路器中过电流脱扣器的额定电流应该大于等于线路的___。
A. 最大过载电流
B. 最大短路电流的
C. 最大允许电流
D. 最大负载电流
【单选题】
接触器的额定电压应不小于主电路的___。
A. 短路电压
B. 工作电压
C. 最大电压
D. 峰值电压
【单选题】
对于工作环境恶劣、启动频繁的异步电动机，所用热继电器热元件的额定电流可选为电动机额定电流的___倍。
A. 0.95～1.05
B. 1.05～1.15
C. 1.15～1.50
D. 0.85～0.95
【单选题】
中间继电器的选用依据是控制电路的___、电流类型、所需触点的数量和容量等。
A. 电压等级
B. 阻抗大小
C. 短路电流
D. 绝缘等级
【单选题】
根据机械与行程开关传力和位移关系选择合适的___。
A. 电流类型
B. 电压等级
C. 接线型式
D. 头部型式
【单选题】
用于指示电动机正处在旋转状态的指示灯颜色应选用___。
【单选题】
BK系列控制变压器适用于机械设备中一般电器的___、局部照明及指示电源。
A. 控制电源
B. 电动机
C. 油泵
D. 压缩机
【单选题】
对于环境温度变化大的场合，不宜选用___时间继电器。
A. 手动式
B. 液压式
C. 晶体管式
D. 电动式
【单选题】
压力继电器选用时首先要考虑所测对象的压力范围，还要符合电路中的额定电压，所测管路___。
A. 绝缘等级
B. 电阻率
C. 接口管径的大小
D. 材料
【单选题】
直流电动机___、价格贵、制造麻烦、维护困难，但是启动性能好、调速范围大。
A. 结构小巧
B. 结构庞大
C. 结构简单
D. 结构复杂
【单选题】
直流电动机的转子由电枢铁心、___、换向器、转轴等组成。
A. 机座
B. 主磁极
C. 电枢绕组
D. 换向极
【单选题】
直流电动机按照励磁方式可分他励、并励、___和复励四类。
【单选题】
直流电动机常用的启动方法有：电枢串电阻启动、___等。
A. 弱磁启动
B. 降压启动
C. Y-△启动
D. 变频启动
【单选题】
直流电动机的各种制动方法中，能平稳停车的方法是___。
A. 能耗制动
B. 再生制动
C. 回馈制动
D. 反接制动
【单选题】
直流串励电动机需要反转时，一般将___两头反接。
A. 补偿绕组
B. 电枢绕组
C. 励磁绕组
D. 换向绕组
【单选题】
绕线式异步电动机转子串频敏变阻器启动与串电阻分级启动相比，控制线路___。
A. 只能自动控制
B. 比较简单
C. 只能手动控制
D. 比较复杂
【单选题】
以下属于多台电动机顺序控制的线路是___。
A. Y-△启动控制线路
B. 一台电动机正转时不能立即反转的控制线路
C. 电动机2可以单独停止，电动机1停止时电动机2也停止的控制线路
D. 电梯先上升后下降的控制线路
【单选题】
多台电动机的顺序控制线路___
A. 必须要主电路和控制电路同时具备该功能才能实现
B. 只能通过主电路实现
C. 既可以通过主电路实现，又可以通过控制电路实现
D. 只能通过控制电路实现
【单选题】
三相异步电动机的位置控制电路中，除了用行程开关外，还可用___。
A. 光电传感器
B. 速度继电器
C. 断路器
D. 热继电器
【单选题】
三相异步电动机反接制动，转速接近零时要立即断开电源，否则电动机会___。
推荐试题
【单选题】
- Jim, please don't put your head out of the window on the bus. It's dangerous!___
A. Good idea.
B. Sorry, I won't do it again.
C. It doesn't matter.
D. It's good.
【单选题】
-How about going fishing?___, I have no patience for that.
A. Excuse me
B. Sorry
C. Pardon
D. Apologize
【单选题】
- Thanks for the lovely and delicious food______.
A. No thanks
B. Never mind
C. All right
D. My pleasure
【单选题】
－ Haven't seen you for ages. Let's have a get-together next week._____
A. Great idea.
B. Welcome!
C. Yes, of course.
D. No, thanks.
【单选题】
- Do you mind if I switch off the radio? ______. Go ahead.
A. Never mind
B. No way
C. No, not at all
D. No, you'd better not
【单选题】
- Could I use your bike for a moment? ___
A. It's well.
B. It doesn't matter.
C. By all means.
D. I have no idea.
【单选题】
-How do you like the story?_______.
A. I'd like to read it
B. I like it very much
C. fine, thank you
D. It's very interesting
【单选题】
- I'll sorry to trouble you.______.
A. Don't say so
B. OK
C. It doesn't matter
D. That's fight
【单选题】
- We ordered 20 boxes of your products, but we have only got 19. - ____
A. You do not have to.
B. It does not matter.
C. We will send another tomorrow.
D. Nothing serious.
【单选题】
--Will you please give the note to him? _________.
A. Certainly, I'll give it to him
B. No, please not
C. Sorry, I don't
D. Yes, please do
【单选题】
- Thank you ever so much for your lovely gift____
A. Never mind
B. I'm glad you like it.
C. Please don't say so.
D. No, It's not so good.
【单选题】
- I'd like to invite you to dinner this Saturday, Mr. Smith.____
A. Oh, no. let's not.
B. I'd rather stay at home.
C. I'm sorry, but I have other plans.
D. Oh, no. That'll be too much trouble.
【单选题】
- Could you please open the window?____
A. I can't.
B. Go ahead.
C. Sure.
D. It's really very kind.
【单选题】
- Do you think I can borrow your bike for a few hours?____
A. I'm afraid you can.
B. I'm sorry, but I really need it this afternoon.
C. Yes, I don't think so.
D. I'll think about it later.
【单选题】
- Thank you very much for the dictionary you sent me.____
A. No thanks.
B. I'm glad you like it.
C. Please don't say so.
D. No, it's not so good.
【单选题】
- How do you like the movie we saw yesterday?____
A. You are welcome.
B. How about you?
C. I've never seen a better movie than it.
D. It is very expensive.
【单选题】
- What do you think of your new teacher____
A. He came to teach us last week.
B. He teaches us English.
C. He has two children.
D. He is very nice.
【单选题】
- Are you going to have a holiday?____
A. Not until next week.
B. Three weeks ago.
C. To Beijing.
D. I'm pleased to hear that.
【单选题】
- You seem to be lost. Need help? ____
A. Yes, would you please help me with the bag?
B. Help me find my key, please.
C. Yes, with pleasure.
D. I'm looking for Zhongshan Road.
【单选题】
- Can you help me clear up the mess____
A. Yes, it doesn't matter.
B. No, that's OK.
C. Yes, help yourself.
D. No problem.
【单选题】
- Does No.20 bus stop at our school?____
A. I go to school by bus.
B. I'm afraid not.
C. You are welcome.
D. I'll not take No.20 bus.
【单选题】
- Can I help you? ____
A. Sorry, I don't need your help.
B. What help can you give us?
C. I'd like to try on these shoes, please.
D. Thanks. You are welcome.
【单选题】
- Sorry to have kept you waiting. ____
A. That's OK.
B. What are you doing?
C. What's wrong with you?
D. Where have you been?
【单选题】
- What is she?____
A. She is a typist.
B. She is talking to her friend.
C. She is having a holiday.
D. She is my sister.
【单选题】
- That's a beautiful cat. I wonder who it belongs to.____
A. It belongs to the
B. rowns. B.The cat is my favourite too.
C. Mind your own business.
D. I can't say anything more.
【单选题】
- Excuse me, could you tell me the time____
A. You'd better buy a watch.
B. It's three thirty by my watch.
C. Can you see the clock?
D. It's late I think.
【单选题】
- What do you think of the movie we saw last night?____
A. The actress is bad.
B. Terrific!
C. The theatre is bad.
D. Nobody was there.
【单选题】
___ No, thanks. I'm just looking around. I'll let you know if I want anything.
A. Could you help me?
B. What will you buy?
C. Can I help you?
D. Do you like to look around?
【单选题】
- Hello, Peter. What do you do?____
A. I am fine.
B. I am not sick.
C. I am a student from Bonn University.
D. I came from Bonn University.
【单选题】
-Excuse me; can I have a seat here?___
A. Be hurry.
B. Come on.
C. Yes, please.
D. Do you mind?
【单选题】
- Shall we sit up here on the grass or down there near the water?___
A. I'd rather stay here if you don't mind.
B. Sorry, I don't like neither.
C. Certainly, why not？
D. Yes, we like these two places.
【单选题】
- What do you do on Sunday?___
A. I 'm a teacher.
B. I play football.
C. You are a student.
D. They clean rooms.
【单选题】
- Our class won the girls' relay race in our school's sports meeting.___
A. That's right.
B. Thanks a lot.
C. Congratulations!
D. It's a pleasure.
【单选题】
- Hi, is Mary there, please?___
A. Hold on. I'll get her.
B. No, she isn't here.
C. Yes, she lives here.
D. Yes, what do you want?
【单选题】
- I am afraid I can't return the book to you before Friday. ___
A. Don't be afraid
B. Be careful
C. Not at all
D. Take your time
【单选题】
- I really don't know how to thank you enough. ___.
A. No problem
B. Think nothing of it
C. Not at all
D. It doesn't matter
【单选题】
- Must I be home before seven? ___.
A. No, you needn't
B. No, you mustn't
C. Yes, you will
D. No, you won't
【单选题】
-I'm sorry to hear that you failed in the exam______.
A. Not at all
B. Oh, thank you.That's very kind of you
C. You are welcome
D. Yes, I'm really sorry
【单选题】
-I will,______.
A. that's all right
B. thank you
C. all right
D. not at all
【单选题】
-Hello, may I speak to Zhao Hua?_____.
A. My name is Zhao Hua
B. I'm Zhao Hua
C. This is Zhao Hua speaking
D. Zhao Hua is me
