【单选题】
Hello, how are you?___
A. Hello, how are you?
B. How do you do?
C. Fine, thank you.
D. That's OK.
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答案
C
解析
暂无解析
相关试题
【单选题】
I didn't mean to do that. Please forgive me。___
A. Not too bad.
B. That's all right
C. It's a pleasure.
D. Thank you.
【单选题】
Thank you for your invitation.___
A. It doesn’t matter.
B. It's a pleasure.
C. It's a small thing.
D. I'll appreciate it.
【单选题】
What a beautiful dress you have on today!___
A. It is suitable for me.
B. No, it isn’t.
C. You want to have one, too?
D. Thank you.
【单选题】
I think he is a good lecturer.___
A. Sorry, it doesn’t matter.
B. So do I.
C. Yes. It's a good idea
D. I don't mind
【单选题】
— What's the matter, dear?___
A. I didn't go to school.
B. I have a terrible headache.
C. I took the kids shopping today.
D. It is a beautiful dress.
【单选题】
Good morning, may I speak to Mark, please?___
A. Who's there?
B. Who's that speaking?
C. Who are you?
D. Who wants to speak to Mark?
【单选题】
Let me introduce myself. I'm Steward.___
A. What a pleasure.
B. Pleased to meet you.
C. I don't know.
D. Thanks a lot.
【单选题】
Let's go to the library this afternoon.___.
A. Yes, that's right.
B. No. I can't.
C. What about you?
D. That's a good idea.
【单选题】
What does Tom's wife do for a living?___.
A. She is a doctor.
B. Tom loves his wife.
C. She has a happy life.
D. She lives far from here.
【单选题】
How tall is your sister?___
A. She is not very well.
B. She is 28 years old.
C. She is very nice.
D. She is as tall as I am.
【单选题】
What do you think of this novel?___
A. I've read it.
B. It's well-written.
C. It was written by my uncle.
D. I bought it yesterday.
【单选题】
How much is this necklace?___
A. It's very nice.
B. It's a birthday present from my parents.
C. It costs fifty pounds.
D. It's a bargain.
【单选题】
How can I get to the cinema?___
A. It's very far.
B. Yes, there is a cinema near here.
C. It's well known.
D. Go down this street and turn left.
【单选题】
What's the matter, John?___
A. I failed my French test
B. It doesn't matter.
C. Nothing's wrong with him.
D. I don't think I can.
【单选题】
What are you majoring in?___
A. In a university.
B. Very hard.
C. Mathematics.
D. At nine in the morning.
【单选题】
Are you going on holiday for a long time?___
A. It was a long time.
B. Two weeks ago.
C. No. Only a couple of days.
D. Not long time ago.
【单选题】
Is Mary there?___
A. Speaking.
B. I'm not Mary.
C. Who are you?
D. Mary is well today.
【单选题】
What day is today?___
A. It's March 6.
B. It's a fine day today.
C. It's March.
D. It's Monday.
【单选题】
Is that seat taken?___
A. Please don't worry.
B. I don't think so.
C. Why not?
D. It's very nice.
【单选题】
Thank you for calling.___
A. Don’t mention it.
B. That's fine.
C. Nice talking to you.
D. Call back again.
【单选题】
How are you getting on today?___
A. Very well.
B. How do you do?
C. I'm a doctor.
D. Nice to have known you.
【单选题】
How's your family?___
A. Thanks all the same.
B. Thanks for calling.
C. Not too bad.
D. Don't mention it.
【单选题】
- How is it that you are late for class again?___
A. Because I missed the bus
B. By bus and then on foot
C. Yes, it is quite wrong
D. It is far from school
【单选题】
- Excuse me. Could you spare me a few minutes? - ___
A. Of course.
B. Of course not.
C. I am sorry to hear that.D.Yes. I'm busy now.
【单选题】
- It's very thoughtful of you to give me a ride. ___
A. It's my pleasure.
B. Take it easy.
C. Sure.
D. Never mind.
【单选题】
- This is heavy! What's in it? ___
A. I think you don't like it.
B. My new computer. I just bought it.
C. I'm glad you're here.
D. Are you really interested in it?
【单选题】
___ I'd like to place an order please.
A. Can I help you?
B. I can help you.
C. What are you doing?
D. Why are you doing?
【单选题】
- Do you know the girl over there?___
A. How can I know?
B. Yes, I remember it now.
C. It's Sam, my teacher's daughter.
D. She is a good girl.
【单选题】
- Shall we go out for dinner tonight?____
A. No, you can't.
B. Yes, please.
C. Thank you, I don't want to.
D. Sorry, I have a report to finish.
【单选题】
- I think the reference book(参考书)is very helpful.____
A. Good idea.
B. So do I.
C. With pleasure.
D. No problem.
【单选题】
- I wish you success in your career.____
A. You are welcome.
B. I think so.
C. Yes, please.
D. The same to you.
【单选题】
- Would you like to come over tonight?____
A. Yes, last night.
B. Yes, over there.
C. Sure, I'd love to.
D. Yeah, I liked it too.
【单选题】
- How do I transfer calls? ____
A. Do as you like.
B. It is a bit difficult.
C. Let me show you.
D. Not at all.
【单选题】
- Thanks for inviting me, John, but I've already made other plans. ____. Maybe another time.
A. I hope you enjoy it
B. That's good
C. Oh! I'm sorry to hear that
D. Great! I really had a good time
【单选题】
- Thanks for the lovely party and the delicious food. ____
A. No, thanks.
B. Never mind.
C. Thank you for coming.D.That's all right.
【单选题】
- Why didn't you tell me? ____
A. Sorry, I forgot.
B. I'm sorry you should wait.
C. I don't know.
D. I'd love to.
【单选题】
- What do you plan to do after the exam? ____ How about you?
A. I hate taking exams.
B. I like making plans.
C. Nothing special.
D. I've changed my mind.
【单选题】
- Tom told me that you collect stamps. ____
A. What do you mean?
B. I don't think so.
C. Why did he tell you?
D. Yes, I do. Do you?
【单选题】
- This is a challenging job. Who wants it?____
A. I'll take it.
B. It's a good idea.
C. You bet!
D. No sweat!
【单选题】
- I'm taking my driving test tomorrow. ___!
A. Cheers
B. Good luck
C. Come on
D. Congratulations
推荐试题
【单选题】
步进电动机的角位移或线位移与___
A. 脉冲数成正比
B. 脉冲频率f成正比
C. 驱动电源电压的大小成正比
D. 环境波动相关
【单选题】
有电枢电压,电动机嗡嘴响但不转,一会出现过流跳闸。故障原因可能是___
A. 电动机气隙碰通不饱和
B. 电动机气隙磁通饱和
C. 高碳电路损坏或没有加励磁
D. 电枢电压过低
【单选题】
直流电动机运行中转速突然急速升高并失控。故障原因可能是___。
A. 突然失去励磁电流
B. 电枢电压过大
C. 电枢电流过大
D. 励磁电流过大
【单选题】
直流电动机启动时设加励磁,电动机会过热烧毁,原因是电动机不转时___导致电枢电流很大。
A. 电枢回路的电阻很小
B. 电枢回路的反电动势很高
C. 电枢电压高
D. 电枢回路的反电动势为零
【单选题】
直流测速发电机输出电压与转速之间并不能保持确定的线性关系。其主要原因是___。
A. 电枢电阻的压降
B. 电枢电流的去磁作用
C. 负载电阻的非线性
D. 电刷的接触压降
【单选题】
双闭环直流调速系统调试中,出现转速给定值U.达到设定最大值时,而转速还未达到要求值,应___。
A. 逐步减小速度负反馈信号
B. 调整速度调节器ASR限幅
C. 调整电流调节器ACR限幅
D. 逐步减小电流负反馈信号
【单选题】
调速系统开机时电流调节器ACR立刻限幅,电动机速度达到最大值,或电动机忽转忽停出现振荡。可能的原因是___。
A. 系统受到严重干扰
B. 励磁电路故障
C. 限幅电路没有整定好
D. 反馈极性错误
【单选题】
直流电动机弱磁调速时,防飞车故障,应加___。
A. 失磁保护电路
B. 防磁饱和电路
C. 过压保护电路
D. 过流保护电路
【单选题】
直流电动机弱磁调速时,励磁电路接线务必可靠,防止发生___。
A. 运行中失磁造成飞车故障
B. 运行中失磁造成停车故障
C. 启动时失磁造成飞车故障
D. 启动时失磁造成转速失控故障
【单选题】
在转速电流双闭环调速系统中,调节给定电压,电动机转速有变化,但电枢电压很低。此故障的可能原因是___。
A. 主电路品闸管损坏
B. 品闸管触发角太小
C. 速度调节器电路故障
D. 电流调节器电路故障
【单选题】
在转速电流双闭环调速系统中,调节速度给定电压,电机转速不变化。此故障的可能原因是___。
A. 品闸管触发电路故障
B. PI调节器限幅值整定不当
C. 主电路晶闸管损坏
D. 电动机励磁饱和
【单选题】
品闸管一电动机调速系统的主回路电流断续时,开环机械特性___。
A. 变软
B. 变硬
C. 不变
D. 电动机停止
【单选题】
双闭环调速系统中转速调节器一般采用Pl调节器,I参数的调节主要影响系统的___
A. 稳态性能
B. 动态性能
C. 静差率
D. 调节时间
【单选题】
在晶闸管可逆调速系统中,为防止逆变失败,应设置___的保护环节。
A. 限制βmin
B. 限制αmin
C. 限制βmin和αmin
D. βmin和αmin任意限制一个
【单选题】
转速电流双闭环调速系统,在负载变化时出现转速偏差,消除此偏差主要靠___
A. 电流调节器
B. 转速、电流两个调节器
C. 转速调节器
D. 电流正反馈补偿
【单选题】
欧陆514调速器组成的电压电流双闭环系统运行中出现负载加重转速升高现象,可能的原因是___。
A. 电流正反馈欠补偿
B. 电流正反馈过补偿
C. 电流正反馈全补偿
D. 电流正反馈没补偿
【单选题】
欧陆514调速器组成的电压电流双闭环系统中,如果要使主回路允许最大电流值减小,应使___。
A. ASR输出电压限幅值增加
B. ACR输出电压限幅值增加
C. ASR输出电压限幅值减小
D. ACR输出电压限幅值减小
【单选题】
在转速电流双闭环调速系统中,电动机转速可调,转速不高且波动较大。此故障的可能原因是___。
A. Pl调节器限幅值电路故障
B. 电动机励磁电路故障
C. 品闸管或触发电路故障
D. 反馈电路故障
【单选题】
电压负反馈调速系统中,若电流截止负反馈也参与系统调节作用时,说明主电路中电枢电流___。
A. 过大
B. 过小
C. 正常
D. 不确定
【单选题】
自动调速系统中转速反馈系数过大会引起___。
A. 系统稳态指标下降
B. 系统最高转速下降
C. 系统最高转速过高
D. 电动机停转
【单选题】
转速电流双闭环调速系统,电动机转速可调,低速时性能正常。但当给定电压大于某个值时电动机转速反而下降,这时速度波动大,系统静差率指标明显恶化。此故障的可能原因有___。
A. 电流调节器ACR限幅值整定不当
B. 速度调节器ASR限幅值整定不当
C. 速度调节器ASR调节器的P参数整定不当
D. 速度调节器ASR调节器的I参数整定不当
【单选题】
在转速电流双闭环调速系统中,调节给定电压,电动机转速有变化,但电枢电压很低。此故障的可能原因是___。
A. 主电路晶闸管损坏
B. 品闸管触发角太小
C. 速度调节器电路故障
D. 电流调节器电路故障
【单选题】
若调速系统反馈极性错误,纠正的办法有___。
A. 直流测速发电机的两端接线对调
B. 电动机电枢的两端接线对调
C. 电动机励磁的两端接线对调
D. 加负给定电压
【单选题】
欧陆514调速器组成的电压电流双闭环逻辑无环流可逆调速系统中,当转矩极性信号改变极性,并有___时,逻辑才允许进行切换。
A. 零电流信号
B. 零电压信号
C. 零给定信号
D. 零转速信号
【单选题】
欧陆514双闭环直流调速系统运行中,测速发电机反馈线松脱,系统会出现___
A. 转速迅速下降后停车,报警并跳闸
B. 转速迅速升高至最大,报警并跳闸
C. 转速保持不变
D. 转速先升高后恢复正常
【单选题】
电动机停车要精确定位,防止爬行时,变频器应采用___方式。
A. 能耗制动加直流制动
B. 能耗制动
C. 直流制动
D. 回馈制动
【单选题】
变频器过载故障的原因可能是___。
A. 加速时间设置太短、电网电压太高
B. 加速时间设置太短、电网电压太低
C. 加速时间设置太长、电网电压太高
D. 加速时间设置太长、电网电压太低
【单选题】
负载不变情况下,变频器出现过电流故障,原因可能是___。
A. 负载过重
B. 电源电压不稳
C. 转矩提升功能设置不当
D. 斜波时间设置过长
【单选题】
变频器一上电就过电流故障报警并跳闸。此故障原因不可能是___。
A. 变频器主电路有短路故障
B. 电动机有短路问题
C. 安装时有短路问题
D. 电动机参数设置问题
【单选题】
电动机拖动大惯性负载,在减速或停车时发生过电压报警。此故障可能的原因是___。
A. UT比设置有问题
B. 减速时间过长
C. 减速时间过短
D. 电动机参数设置错误
【单选题】
设置变频器的电动机参数时,要与电动机铭牌数据___。
A. 完全一致
B. 基本一致
C. 可以不一致
D. 根据控制要求变更
【单选题】
西门子MM420变频器参数P0004=3表示要访问的参数类别是___。
A. 电动机数据
B. 电动机控制
C. 命令和数字I/O
D. 变频器
【单选题】
一台使用多年的250kW电动机拖动鼓风机,经变频改造运行两个月后常出现过流跳闸。故障的原因可能是___。
A. 变频器选配不当
B. 变频器参数设置不当
C. 变频供电的高频谐波使电动机绝缘加速老化
D. 负载有时过重
【单选题】
变频器运行时过载报警,电动机不过热。此故障可能的原因是___。
A. 变频器过载整定值不合理,电动机过载
B. 电源三相不平衡,变频器过载整定值不合理
C. 电动机过载,变频器过载整定值不合理
D. 电网电压过高,电源三相不平衡
【单选题】
一合大功率电动机,变频器调速运行在低速段时电动机过热。此故障的原因可能是___。
A. 电动机参数设置不正确
B. U/f比设置不正确
C. 电动机功率小
D. 低速时电动机自身散热不能满足要求
【单选题】
变频器轻载低频运行,启动时过电流报警。此故障的原因可能是___。
A. U/f比设置过高
B. 电动机故障
C. 电动机参数设置不当
D. 电动机容量小
【单选题】
变频调速时,电动机出现过热,___的方法不能改进过热问题。
A. 尽可能不要低频运行
B. 换用变频电动机
C. 改进散热条件
D. 提高电源电压
【单选题】
教启动器启动完成后,旁路接触器刚动作就跳用。故障原因可能是___。
A. 启动参数不适合
B. 晶闸管模块故障
C. 启动控制方式不当
D. 旁路接触器与软启动器的接线相序不一致
【单选题】
软启动器进行启动操作后,电动机运转,但长时间达不到额定值。此故障原因不可能是___。
A. 启动参数不合适
B. 启动线路接线错误
C. 启动控制方式不当
D. 品闸管模块故障
【单选题】
教启动器启动完成后,旁路接触器刚动作就跳闸。故障原因可能是___。
A. 启动电流过大
B. 旁路接触器接线相序不对
C. 启动转矩过大
D. 电动机过载