【单选题】
20TTL电路在正逻辑系统中，以下各种输入中___相当于输入逻辑“0”。
A. 悬空
B. 通过电阻2.7kΩ接电源
C. 通过电阻2.7kΩ接地
D. 通过电阻510Ω接地
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相关试题
【单选题】
21对于TTL与非门闲置输入端的处理，不可以___。
A. 接电源
B. 通过电阻3kΩ接电源
C. 接地
D. 与有用输入端并联
【单选题】
22STTL数字集成电路与CMO数字集成电路相比突出的优点是___。
A. 微功耗
B. 高速度
C. 高抗干扰能力
D. 电源范围宽
【单选题】
23以下式子中正确的是___
A. 1+A＝A
B. A＋A=1
C. A•A＝1
D. A+AB=A
【单选题】
在一个四变量逻辑函数中，___为最小项。
【单选题】
A+BC=___。
A. A+B
B. A+C
C. （A+B）（A+C）
D. B+C
【单选题】
26以下代码中为无权码的为___。
A. 5421BCD码
B. 8421BCD码
C. 余三码
【单选题】
一位十六进制数可以用___位二进制数来表示。
【单选题】
28十进制数25用8421BCD码表示为___。4位
A. 10 101
B. 0010 0101
C. 100101
D. 10101
【单选题】
29与十进制数（53.5）10不等值的数或代码为___。
A. (0101 0011.0101)8421BCD
B. (35.8)16
C. (110101.1)2
D. (60.4)8
【单选题】
30与八进制数(47.3)8等值的数为___
A. (100111.011)2
B. (97.3)16
C. (27.3 )16
D. (100111.11)2
【单选题】
31下列各型号中属于优先编码器是___。
A. 74LS85
B. 74LS138
C. 74LS148
D. 74LS48
【单选题】
七段数码显示器BS202是___。
A. 共阳极LED管
B. 共阴极LED管
C. 共阳极LCD管
D. 共阴极LCD管
【单选题】
33八输入端的编码器按二进制数编码时，其输出端的个数是___。
【单选题】
四输入的译码器，其输出端最多为___。
A. 4个
B. 8个
C. 10个
D. 16个
【单选题】
当74LS148的输入端按顺序输入11011101时，输出为___。
A. 101
B. 010
C. 001
D. 110
【单选题】
用三线-八线译码器74LS138和辅助门电路实现逻辑函数Y=a2+a1a2，应___。
A. 用与非门，Y=y0y1y4y5y6y7
B. 用与门，Y=y2y3
C. 用或门，Y=y2+y3
D. 用或门，Y=y0+y1+y4+y5+y6+y7
【单选题】
37时序逻辑电路中一定包含___。
A. 触发器
B. 组合逻辑电路
C. 移位寄存器
D. 译码器
【单选题】
仅具有置“0”和置“1”功能的触发器是___。
A. 基本RS触发器
B. 钟控RS触发器
C. D触发器
D. JK触发器
【单选题】
由与非门组成的基本RS触发器不允许输入的变量组合为___。
【单选题】
40仅具有保持和翻转功能的触发器是___。
A. JK触发器
B. T触发器
C. D触发器
D. T' 触发器
【单选题】
触发器由门电路构成，但它不同于门电路功能，主要特点是___。
A. 具有翻转功能
B. 具有保持功能
C. 具有记忆功能
【单选题】
TTL集成触发器直接置0端[]和直接置1端[]在触发器正常工作时应___。
A. =1，=0
B. =0，=1
C. 保持高电平“1”
D. 保持低电平“0”
【单选题】
按逻辑功能的不同，双稳态触发器可分为___。
A. RS、JK、D、T等
B. 主从型和维持阻塞型
C. TTL型和MOS型
D. 上述均包括
【单选题】
同步计数器和异步计数器比较，同步计数器的显著优点是___。
A. 工作速度高
B. 触发器利用率高
C. 电路简单
D. 不受时钟CP控制。
【单选题】
把一个五进制计数器与一个四进制计数器串联可得到___进制计数器。
【单选题】
下列逻辑电路中为时序逻辑电路的是___ 。
A. 变量译码器
B. 加法器
C. 数码寄存器
D. 数据选择器
【单选题】
47N个触发器可以构成最大计数长度{进制数}为___ 的计数器。
【单选题】
N个触发器可以构成能寄存___位二进制数码的寄存器。
【单选题】
49五个D触发器构成环形计数器，其计数长度为___。
【单选题】
同步时序电路和异步时序电路比较，其差异在于后者___。
A. 没有触发器
B. 没有统一的时钟脉冲控制
C. 没有稳定状态
D. 输出只与内部状态有关
【单选题】
一位8421BCD码计数器至少需要___个触发器。
【单选题】
某电视机水平-垂直扫描发生器需要一个分频器将31500HZ的脉冲转换为60HZ的脉冲，欲构成此分频器至少需要___个触发器。
A. 10
B. 60
C. 525
D. 31500
【单选题】
555定时器属于___
A. 时序逻辑电路
B. 组合逻辑电路
C. 模拟电子电路
【单选题】
54多谐振荡器可产生 ___
A. 正弦波
B. 矩形脉冲
C. 三角波
D. 锯齿波
【单选题】
脉冲整形电路有___。
A. 多谐振荡器
B. 施密特触发器
C. 555定时器
【单选题】
56石英晶体多谐振荡器的突出优点是___ 。
A. 速度高
B. 电路简单
C. 振荡频率稳定
D. 输出波形边沿陡峭
【单选题】
TTL单定时器型号的最后几位数字为___。
A. 555
B. 556
C. 7555
D. 7556
【单选题】
555定时器不可以组成___。
A. 多谐振荡器
B. 单稳态触发器
C. 施密特触发器
D. JK触发器
【单选题】
59以下各电路中，___可以产生脉冲定时。
A. 多谐振荡器
B. 单稳态触发器
C. 施密特触发器
D. 石英晶体多谐振荡器
【单选题】
555定时电路端不用时，应当___。
A. 接高电平
B. 接低电平
C. 通过0.01µF的电容接地
D. 通过小于500Ω的电阻接地
推荐试题
【单选题】
某公司2015年度的税后利润为1200万元，该年分配股利600万元，2017年拟投资1000万元引进一条生产线以扩大生产能力，该公司目标资本结构为自有资金占80%，借入资金占20%。该公司2016年度的税后利润为1300万元。要求回答如下问题：如果该公司执行的是固定股利政策，并保持资本结构不变，2017年外部自有资金筹集数额为___元
A. 300
B. 100
C. 400
D. 200
【单选题】
某公司2015年度的税后利润为1200万元，该年分配股利600万元，2017年拟投资1000万元引进一条生产线以扩大生产能力，该公司目标资本结构为自有资金占80%，借入资金占20%。该公司2016年度的税后利润为1300万元。要求回答如下问题：如果该公司执行的是固定股利支付率政策，并保持资本结构不变，2015年股利支付率为___
A. 30%
B. 40%
C. 50%
D. 60%
【单选题】
某公司2015年度的税后利润为1200万元，该年分配股利600万元，2017年拟投资1000万元引进一条生产线以扩大生产能力，该公司目标资本结构为自有资金占80%，借入资金占20%。该公司2016年度的税后利润为1300万元。要求回答如下问题：如果该公司执行的是固定股利支付率政策，并保持资本结构不变，2016年公司留存利润为___元
A. 400
B. 450
C. 550
D. 650
【单选题】
How did the speaker feel about his childhood? ___
A. Alone.
B. Happy.
C. Sad.
D. Interesting.
【单选题】
Which is NOT mentioned when the speaker curled up in a chair? ___
A. Reading fairytales and myths.
B. Daydreaming.
C. Writing poems.
D. Listening to music.
【单选题】
What kind of person was the speaker’s grandma? ___
A. Often critical, judgmental.
B. Very strict.
C. Easygoing.
D. Successful.
【单选题】
When was the speaker’s first conscious memory of feeling different? ___
A. Fourth grade.
B. Fifth grade.
C. First grade.
D. Second grade.
【单选题】
Which is NOT included in the speaker’s inner world? ___
A. Reading books.
B. Writing.
C. Watching TV.
D. Daydreaming.
【单选题】
What does integrity mean? ___
A. You do what you do because it's fashionable.
B. You do what you do because it's politically correct.
C. You do what you do because it's right.
D. You do what you do because somebody asked you to.
【单选题】
Is there cheating in World Cup? ___
A. It's none.
B. It's rare.
C. It's some.
D. It's popular.
【单选题】
Which one of the following situations is NOT mentioned for making us upset? ___
A. Some reward we thought we deserved has been denied us.
B. Some man we helped has proved ungrateful.
C. Some man we believed to be a friend has betrayed us.
D. Some woman we believed to be a friend has spoken ill of us.
【单选题】
In which year the Tour of France was hit by a drug-taking scandal? ___
A. In 1996.
B. In 1997.
C. In 1998.
D. In 1999.
【单选题】
Cheap fake products are everywhere except ___
A. clothes.
B. cut-price DVDs.
C. cut-price CDs.
D. cosmetics.
【单选题】
What should we do after exercise? ___
A. Stretch the muscles.
B. Have a sleep.
C. Maintain high body temperature.
D. Take a shower.
【单选题】
What shouldn’t we wear when we exercise? ___
A. Properly fitted sportswear.
B. Well-fitted sneakers.
C. Tight pants.
D. Sports bra for women.
【单选题】
Which of the following is NOT good for health? ___
A. Training with a friend.
B. Slack off a fitness regimen.
C. Keep our body hydrated.
D. Take small sips every few minutes.
【单选题】
What does the speaker do? ___
A. Public relations consultant.
B. Home cook.
C. Website administrator.
D. Writer.
【单选题】
Which is NOT included in the speaker’s favorite breakfasts? ___
A. Egg.
B. Prosciutto.
C. Papaya.
D. Cabbage.
【单选题】
When do the students start learning Chinese? ___
A. Since kindergarten
B. Since elementary school
C. Since middle school
D. Since high school
【单选题】
When can the students continue studying Chinese? ___
A. In elementary school and middle school.
B. In middle school and high school.
C. In high school and university
D. After the university.
【单选题】
How many American students are currently learning Chinese? ___
A. About 22,000
B. About 24,000
C. About 44,000
D. About 2,400
【单选题】
How much did the Defense Department give Oregon schools? ___
A. $70,000
B. $1.3 million
C. $700,000
D. $1.3 billion
【单选题】
What’s Isabel Weiss’s purpose of learning Chinese? ___
A. For fun
B. For more opportunities for jobs
C. For more opportunities of making money
D. For more opportunities for promotions
【单选题】
What ability do the standardized tests reward to? ___
A. Think.
B. Create.
C. Quickly answer superficial questions.
D. Above all.
【单选题】
In what ways the IQ scores can be changed? ___
A. Training.
B. Nutrition.
C. More friendly people administered the test.
D. Above all
【单选题】
What do schools focus on? ___
A. Concepts.
B. Science.
C. Social Studies.
D. Foreign languages.
【单选题】
Why tests and standards are a necessary fact of life? ___
A. They protect us from hazardous products.
B. They protect us from inept drivers.
C. They protect us from shoddy professionals.
D. Above all.
【单选题】
How many percent did the scores on statewide tests rise? ___
A. 4%.
B. 14%.
C. 40%.
D. None.
【单选题】
What was the woman’s reaction when she was nominated? ___
A. She was surprised at the nomination.
B. She was calm at the nomination.
C. She was indifferent to the nomination.
D. She was scared of the nomination.
【单选题】
According to the woman, who paid for her trip to San Francisco? ___
A. Her trip to San Francisco was sponsored by the Academy.
B. Her trip to San Francisco was paid for by her company.
C. Her trip to San Francisco was paid for by her family.
D. Her trip to San Francisco was paid for by herself.
【单选题】
What is the name of George Miller’s new movie? ___
A. Happy Feeling.
B. Happy Dancing.
C. Happy Foot.
D. Happy Feet.
【单选题】
Which name is not mentioned in the film? ___
A. Nicole Kidman.
B. Hugh Jackman.
C. George Clooney.
D. Robin Williams.
【单选题】
Which of the following statement is not true about “Life in the Freezer”? ___
A. It was a documentary film.
B. It was made by National Geographic and the BBC.
C. It was a story of the amazing life of Emperor penguins.
D. The
E. mperor penguin sang to each other to find a mate and made friends.
【单选题】
What should you do during a high-pressure periods? ___
A. Lock yourself in a room with your work.
B. Leave your work and go on a vocation.
C. Tell your boss you can’t finish your work.
D. Get together with people who will revitalize and inspire you.
【单选题】
Which of the following is the correct description of TempWorld? ___
A. The era of guaranteed jobs is history.
B. We are all temporary workers.
C. You have to equip yourself with the skills.
D. All of the above.
【单选题】
What should a career activist do? ___
A. Being a career activist means concentrating on daily business.
B. Being a career activist means you can do a business as long as it meets your short-term needs.
C. A career activist should take the long view of his career.
D. A career activist should plan everything in advance.
【单选题】
What should you do in the TempWorld? ___
A. In TempWorld you must withstand disappointment, juggle stressful situations, and handle pressure.
B. You must learn from your setbacks and use them to your advantage in the future.
C. Things always go well for successful people because they are honest.
D. Both A and B.
【单选题】
Which of the following statements is Not True? ___
A. Your boss may be willing to change his behavior than your think.
B. Some managers don’t care how much their words or actions upset staffers.
C. You should tell your managers how their outbursts make you feel.
D. If the boss values your work, he may stop his abusiveness.
【单选题】
Which of the following public places is NOT mentioned that have banned mobiles? ___
A. restaurants
B. gas stations
C. theatres
D. museums
【单选题】
What happened when the cellphone of the speaker’s friend rang? ___
A. His friend answered the phone and the speaker became invisible to his friend.
B. They answered the phone together.
C. The speaker threw away his friend’s cellphone.
D. His friend hung up the phone and kept talking to the speaker. (C)
