相关试题
【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
【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
推荐试题
【单选题】
心神的物质基础是___
A. 血
B. 气
C. 精
D. 津
E. 营气
【单选题】
津液变成汗、尿是气的何种功能___
A. 推动作用
B. 温照作用
C. 防御作用
D. 气化作用
E. 固摄作用
【单选题】
津液输布的主妥通道为___
A. 经络
B. 赎理
C. 尿道
D. 三焦
E. 骨
【单选题】
气的运行受阻，运行不利，称为___
A. 气滞
B. 气结
C. 气闭
D. 气机不畅
E. 气机失调
【单选题】
与人的睡眠有密切关系的气是___
A. 宗气
B. 元气
C. 卫气
D. 营气
E. 牌气
【单选题】
机体内物质转化和能量转化过程有赖于气的___
A. 推动作用
B. 温熙作用
C. 固摄作用
D. 气化作用
E. 防御作用
【单选题】
下列哪一项是人体正常水液的总称___
A. 体液
B. 阴液
C. 津液
D. 津
E. 液
【单选题】
津液化为汗液排出体外，主要依赖于什么作用___
A. 心主血脉
B. 肺主宣发
C. 肾主气化
D. 肝主疏泄
E. 脾主统摄
【单选题】
下列除哪一项外均是血液正常运行所必需的条件___
A. 血液充盈
B. 脉道通畅
C. 肺脾肾功能正着
D. 心气充沛
E. 三焦通利
【单选题】
气能生津的机理是___
A. 气为生津的物质基础
B. 气为生津的动力
C. 气为生津的物质基础和动力
D. 气能化生精气
E. 气能生血，血能化津
【单选题】
血和津液生成的共同物质来源是___
A. 水谷精微
B. 宗气
C. 精
D. 元气
E. 营气
【单选题】
昼行于阳，夜行于阴的气是___
A. 营气
B. 卫气
C. 元气
D. 宗气
E. 肾气
【单选题】
“夺血者无汗”的生理基础是___
A. 肝肾同源
B. 乙类同源
C. 津血同源
D. 精血同源
E. 以上均不是
【单选题】
Q1: What does the man suggest that the woman do this weekend?___
A. Read J .K .Rowling's first book .
B. Go to buy a new Harry Potter book .
C. Watch BBC news about J .K .Rowling .
D. Take her cousin to see a new Harry Potter movie .
【单选题】
Q2: Where did J. K. Rowling come up with the idea for Harry Potter?___
A. At a cafe .
B. On a train .
C. At a cinema .
D. In a bookstore .
【单选题】
Q3: What are J. K. Rowling’s future plans?___
A. She won't write any more books .
B. She will write more magic stories .
C. She hasn't said anything about her future plans .
D. She said she would work on more serious subjects .
【单选题】
Q4: What are the two speakers mainly talking about?___
A. J.K. Rowling's secret .
B. J .K .Rowling's writing plan .
C. A new book by J .K.Rowling.
D. An interview with J .K .Rowling .
【单选题】
Q1: What happened when Stephen tried to remove a bottle of milk from the refrigerator?___
A. He broke the milk bottle .
B. He fell down on the floor .
C. He made a mess inside the refrigerator .
D. He spilled the milk over the kitchen floor .
【单选题】
Q2: What did Stephen’s mother do when she came into the kitchen？___
A. She gave him a long lecture .
B. She shouted at him in anger .
C. She enjoyed the wonderful mess .
D. She cleaned up the mess with him .
【单选题】
Q3: What did Stephen’s mother teach him later?___
A. How to do an experiment .
B. How to carry a milk bottle .
C. How to clean up spilled milk .
D. How to avoid making mistakes .
【单选题】
Q4: What did Stephen learn from this experience?___
A. Mistakes can become learning opportunities .
B. Mistakes are just like scientific experiments .
C. One should sometimes make mistakes .
D. One should try to avoid making mistakes .
【单选题】
Q1: Why is surfing the man’s favorite activity?___
A. Because he likes the sunny weather.
B. Because he wants to challenge himself .
C. Because it can help solve his sleeping problem .
D. Because it can help him forget all his troubles .
【单选题】
Q2: What is the woman going to do this weekend?___
A. To go sailing .
B. To go surfing .
C. To go to the beach .
D. To go to her nephew's .
【单选题】
Q3: What does the woman love doing?___
A. Going to visit relatives.
B. Enjoying the warm sun on the beach .
C. Building sand castles with her niece and nephew .
D. Playing in the sand and jumping in the waves .
【单选题】
Q4: What does the man remember doing with his brothers?___
A. Surfing in the sea .
B. Collecting seashells .
C. Building sand castles .
D. Jumping in the waves .
【单选题】
Q1: According to the survey, what percentage of British adults watched TV in theirfree time?___
A. 89 percent .
B. 84 percent .
C. 76 percent .
D. 71 percent .
【单选题】
Q2: Which age group would be the most likely to visit their friends and relatives?___
A. People aged 16 to 24
B. People aged 25 to 34 .
C. People aged 16 and over .
D. People aged 55 and over .
【单选题】
Q3: What does the speaker say about listening to music as a leisure activity for British people?___
A. People aged 16 to 24 preferred listening to music most .
B. It was getting more and more popular among the British people .
C. It was the third most popular activity among people aged 55 and over .
D. People aged 25 to 34 listened to music more often than those aged 16 to 24 .
【单选题】
Q4: According to the survey, how are leisure activities related to age?___
A. Older people go out to pubs more often . frequently .
B. Younger people go to the cinema less frequently.
C. Older people spend more time reading and gardening .
D. Younger people spend less time visiting friends and family .
【单选题】
Q1: Why was the girl excited?___
A. She is going to have a lot of vanilla ice cream .
B. She won the spelling competition at her school .
C. She is going to the state capital for a competition .
D. She "excellence"correctly,but others didn't .
【单选题】
Q2: What happened when the man was 13 years old?___
A. His family moved to Sacramento to settle down .
B. His family bought him a new suit and a new tie .
C. He went to Sacramento for a spelling competition .
D. He won the first prize in the state spelling competition .
【单选题】
Q3: Why did the man’s mom give him a big hug?___
A. To make him feel better after he lost the first prize .
B. To apologize for not buying him some ice cream .
C. To wish him good luck in the next competition .
D. To congratulate him on winning the first prize .
【单选题】
Q4: What color is the girl going to wear for her next competition?___
A. Red .
B. Blue .
C. Green .
D. Yellow .
【单选题】
Q1: What is this passage mainly about?___
A. Superstitions and science .
B. Tips on how to have good luck .
C. Superstitions in the United States .
D. Rational and superstitious societies .
【单选题】
Q2: According to the passage, what is considered as bad luck?___
A. Walking under a ladder .
B. Dreaming of a black cat .
C. Hanging a mirror in the house .
D. Stepping on one's own shadow .
【单选题】
Q3: Why is it considered bad luck to see a black cat crossing one’s path?___
A. Because black cats look like witches . e witches .
B. Because black cats were thought to be witches .
C. Because black cats bring seven years of bad luck .
D. Because black cats are hard to notice in darkness .
【单选题】
Q4: According to the passage, what will bring people good luck?___
A. Breaking a mirror on purpose .
B. Catching a falling leaf on one's birthday .
C. Finding a on the ground and picking it up .
D. Dreaming of blowing out the candles in one blow .
