相关试题
【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
【单选题】
89S51的内部程序存储器与数据存储器容量各为多少？___
A. 64KB、128B
B. 4KB、64KB
C. 4KB、128B
D. 8KB、256B
【单选题】
89S51比89C51多出了哪个功能？___
A. 存储器加倍
B. 具有WDT工能
C. 多了一个8位输入/输出端口
D. 多了一个串行口
【单选题】
6在DIP40封装的8×51芯片里，复位RESET引脚的引脚编号是什么？___
【单选题】
7在DIP40封装的8×51芯片里，接地引脚与电源引脚的引脚编号是什么？___
A. 1、21
B. 11.31
C. 20、40
D. 19、39
【单选题】
9在12MHz始终脉冲的8051系统里，一个机器周期有多长？___
A. 1µs
B. 12µs
C. 1ms
D. 12ms
【单选题】
12下列哪个寄存器是8×51内的16位寄存器？___
【单选题】
14在8×51的输入/输出端口里，哪个输入/输出端口执行在输出功能时没有内部上拉电阻？___
【单选题】
8×51的P0采用哪种电路结构？___
A. 集电极开路式输出
B. 基极开路式输出
C. 发射机开路式输出
D. 图腾柱输出
【单选题】
17在8×51里，若要扩展外部存储器时，数据总线连接哪个输入/输出端口？___
【单选题】
点亮一般的LED所耗用的电流约为多少？___
A. 1~5µA
B. 10~20µA
C. 1~5mA
D. 10~20mA
【单选题】
19一般地，蜂鸣器属于哪种负载？___
A. 电阻性负载
B. 电感性负载
C. 电容性负载
D. 不导电负载
【单选题】
7405/7406的输出采用哪种电路结构？___
A. 集电极开路式输出
B. 基极开路式输出
C. 发射机开路式输出
D. 图腾柱输出
【单选题】
21在继电器中，NO接点是一种什么接点？___
A. 不使用接点
B. 不存在接点
C. 激磁后即开路的接点
D. 常开接点
【单选题】
22所谓2P的继电器，代表什么意思？___
A. 只有2个接点
B. 两相的负载
C. 两组电源
D. 2组c接点
【单选题】
23共阳极七段数码管显示器的驱动信号有何特色？___
A. 低电平点亮
B. 低电平不亮
C. 高电平点亮
D. 以上皆非
【单选题】
24在8×51的程序里，若要将某个输入/输出端口设置成输入功能，应如何处理？___
A. 先输出高电平到该输入/输出端口
B. 先输出低电平到该输入/输出端口
C. 先读取该输入/输出端口的状态
D. 先保存该输入/输出端口的状态
【单选题】
8×51提供几个外部中断和定时器/计数器中断？___
A. 2,2
B. 3,6
C. 2,3
D. 3,7
【单选题】
8×51的IP缓存器的功能如何？___
A. 设置中断优先级
B. 启动中断功能
C. 设置中断触发信号
D. 定义CPU的网址
【单选题】
28若要让采用低电平触发，则应如何设置？___
A. EX0=0
B. EX0=1
C. IT0=0
D. IT0=1
【单选题】
29在Keil µVision3里进行调试/仿真时，在哪里操作才能触动程序中断？___
A. 在Interrupt System
B. 在Cotorl Box对话框里
C. 直接单击魔术棒按钮即可
D. 直接按0键
【单选题】
30在8×51所提供的中断功能里，下列哪个优先级比较高？___
A. T1
B. RI/TI
C. T0
D. INT0
【单选题】
31在TCON缓存里，IE1的功能是什么？___
A. 触发 IE1中断
B. 指示IE1中断的标志
C. 提高IE1优先等级
D. 取消IE1中断
【单选题】
32在Keil C里，中断子程序与函数又何不同？___
A. 中断子程序不必声明
B. 函数不必声明
C. 中断子程序必须有形式参数
D. 中断子程序一定会有返回值
【单选题】
33若要同时启用INT0及INT1中断功能，则应如何设置？___
A. TCON=0×81
B. IE=0×85
C. IP=0×83
D. IE=0×03
【单选题】
35在8×51的Timer里，若使用Mode 0，其最大计数值为多少个机器周期？___
A. 65636
B. 8192
C. 1024
D. 256
【单选题】
36在12MHz的8×51系统里，哪一种方式一次可定时5ms？___
A. Mode 0及Mode 1
B. Mode 1及Mode 2
C. Mode 2及Mode 3
D. Mode3及Mode 1
【单选题】
37若要让Timer作为外部计数只用，应如何设置？___
A. Gate=0
B. Gate=1
C. C/=0
D. C/=1
【单选题】
39下列哪个不是8×51所提供的省电方式？___
A. PD方式
B. IDL方式
C. LP方式
D. 待机方式
【单选题】
89S51的看门狗有何作用？___
A. 重复执行程序
B. 找回遗失数据
C. 复位系统
D. 防止中毒
【单选题】
41若要启用WDT，则应依次填入WDTRST寄存器哪些数据？___
A. 0xe1、0xe2
B. 0xe1、0x1e
C. 0x1e、0xe1
D. 0x10、0x01
【单选题】
8×51的定时器，在下列哪种方式下具有自动加载功能？___
A. Mode0
B. Mode1
C. Mode2
D. Mode3
【单选题】
45下列哪种AD转换器的转换速度比较快？___
A. 双斜率型AD转换器
B. 比较型AD转换器
C. 连续计数式AD转换器
D. 逐渐接近式AD转换器
【单选题】
46下列哪种AD转换器的精密度比较高？___
A. 双斜率型AD转换器
B. 比较型AD转换器
C. 连续计数式AD转换器
D. 逐步逼近式AD转换器
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【填空题】
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1 In our class,most discussions and activities take place in assigned small groups,These groups provide a supportive and safe environment that （） learning
【填空题】
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9 As the finance ministry rejected the defor its "lack of clarity",it[ ]complaint with the Europear Commission that this deal was against the law
【填空题】
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5 State governments and the colleges themselves have [ ] financial help to students with special abilities and those with financial needs
【填空题】
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10 Dogs cannot distinguish the color of trafficlights, so the master must make the decision of when it is safe to [ ] across the road
【填空题】
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6 The committee agreed that his papers
[ ] a wider circulation because of their essential and fundamental interest to a larger audience.
【填空题】
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1 Because women often restrict their diet
In an effort to control weight,they may
Not consume enough iron-rich food and
( ) experience an iron Deficiency.
【填空题】
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8 Americans defend the right to obtain a gun and they have[ ] been willing to turn a blind eye to the harm that people owning guns have caused
【填空题】
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7 The anger and frustration [ ] by the local people who do not understand what is happening to them will be a terrible and dangerous force
【填空题】
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2 Some reform advocates ignore the impact of
Class size on student achievement,and they
are ( ) what they call as a Priority:teacher effectiveness.
【填空题】
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3 Because of easy access to the Internet,the
New breakthrough tq create something
Truly creative ( ) happen anytime now.
【填空题】
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4 Indeed,if teachers want to( ) how far students might get in life, a better measurement than grades might be how hard the students try.
【填空题】
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5 Nature has( ) these animals ( ) a capacity for not showing Fear.
【填空题】
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6 During the weeks of discussion,delegations
from groups who are interested in the
Resolution may call on representatives to
( ) their point of view.
【填空题】
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7 Plato was a superb writer,and his works are
Part of the world’s great literature.Most of
His existing work is ( )Dialogs and letters.
【填空题】
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8 Young people should enter into a broad
Flexible training program,through which
They can learn a lot and be ( ) their future careers.
【填空题】
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9 The young man is very happy and proud to
be ( ) the old professor because he always feeIs great when talking With him.
【填空题】
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10 One day they passed more than 20 villages ( ),and some of these are Said to have stretched for six miles or more.
【填空题】
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7 Being asingle parent,there is no way for her
to ( ) the time and energy she has
devoted to her children for the past 10 years.
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8 It is essential that you start by listening because one of the main ( ) teenagers and their parents face in forming positive relationships is that neither listens to the other.
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9 We all know the dangers of an earthquake: the ( ) to buildings,the troubles can be caused by falling trees,and the terror occurs when the earth actually opens uip.
【填空题】
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10 Not until recently have we realized that the increasing world population may lead to a potential gloomy ( ) for humanity starvation.
【填空题】
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2 It is the development strategy/of the company to ( ) its overseas expansion in order to take a slice of the world market
【填空题】
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3 Nearly six million people go to see the Mona
Lisa every year,attracted by the ( )of her smile.When you're not lodking at her, she seems to be smiling;when you look at her,she stops.
【填空题】
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4 To live with a family whose native language is English is the ideal way to further improve one's English and to gain ( )into its culture.
【填空题】
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5 There is a real need to ( ) academic
achievement in schools and help with the
development of a student's overall character.
【填空题】
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6 Einstein said his scientific discoveries grew
from his imagination rather than from( ),
reason and language.
【填空题】
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1 When the police caught up with him, Mr.Foster had to [ ] that he'd broken the speed limit.
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2 Whenever my boss makes a decision that I don't agree with, I tell him what I really think, though it's [ ] to make him happy by telling him his ideas are always right
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3 As can be probably perceived, a manned tip to Mars may soon[ ] since scientists have achieved the manned moon mlssion
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4 A number of countries are [ ]their efforts to send out food to the area worst affected by the flood.
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She authorizcd her partner to carry out daily responsibllitles [ ]when she was on her business trip
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On hering the latest news about your mother's ill health, I [ ]canceling your reservation at the Sheraton.
【填空题】
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There was an obvious indication that the police who have to enforce the new law were not[ ] the general discontent.
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When she heard of her failure in the experiment, her eyes[ ]tears; whether it was of shame, frustration, orgrief was difficult to tell.
【填空题】
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Rose knows that continuous letters fromJohn, together with countless roses are aimedat making her[ ]him.
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[ ]public school for drinking and smoking and then failing inshow business as a singer, she joined her father's business 10 years ago.
