相关试题
【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
【单选题】
47对于8×8 LED点阵而言，其中的LED个数及引脚各为多少？___
A. 64、16
B. 16、16
C. 64、12
D. 32、12
【单选题】
48在共阳极型8×8 LED点阵里，其阳极如何连接？___
A. 各行阳极连接到行引脚
B. 各列阳极连接到列引脚
C. 各行阳极连接到列引脚
D. 各列阳极连接到行引脚
【单选题】
49在共阳极型8×8 LED点阵里，其阴极如何连接？___
A. 各行阴极连接到行引脚
B. 各列阴极连接到列引脚
C. 各行阴极连接到列引脚
D. 各列阴极连接到行引脚
【单选题】
50双色8×8 LED点阵的列引脚与行引脚各位多少？___
A. 12、12
B. 8、16
C. 16、8
D. 24、8
推荐试题
【单选题】
The British government is characterized by a division of powers between three of the following branches with the exception of the .
A. A. judiciary
B. B. legislature
C. C. monarchy
D. D. executive
【单选题】
The importance of the British monarchy can be seen in its effect on .
A. A. passing the bills
B. B. advising the government
C. C. political parties
D. D. public attitude
【单选题】
British Cabinet works on the principle of .
A. A. collective responsibility
B. B. individual responsibility
C. C. defending the collectivism
D. D. defending the individuals
【单选题】
The main duty of the British Privy Council is to .
A. A. make decisions
B. B. give advice
C. C. pass bills
D. D. supervise the Cabinet
【单选题】
is the first African-American winner of the Nobel Prize for Literature.
A. A.Ralph Ellison
B. B. Tony Morrison
C. C. Richard Wright
D. D. James Baldwin
【单选题】
Of the following writers, is Not a Nobel Prize winner.
A. A. Alice Walker
B. B. Ernest Hemingway
C. C. William Faulkner
D. D. Eugene O’Neil
【单选题】
Of the following books, is NOT written by Ernest Hemingway.
A. A. The Sun Also Rises
B. B. The Sound and the Fury
C. C. A Farewell to Arms
D. D. For Whom the Bell Tolls
【单选题】
F. Scott Fitzgerald’s finest novel is , and its theme is about
A. A. The Great Gatsby, the American Dream
B. B. Tender is the Night, love
C. C. Tales of the Jazz Age, the loss of oneself
D. D. The Beautiful and the Damned, the evil of human nature
【单选题】
Of the following writers, is NOT included in the group of naturalists.
A. A. Stephen Crane
B. B. Frank Norris
C. C. Theodore Dreiser
D. D. Herman Melville
【单选题】
Of the following, is NOT characteristic of Mark Twain’s works.
A. A. colloquial speech
B. B. a sense of humor
C. C. a realistic view
D. D. an idealistic view
【单选题】
Of the following, is considered Herman Melville’s masterpiece.
A. A. The Last of the Mohicans
B. B. The Legend of Sleepy Hollow
C. C. Moby Dick
D. D. Daisy Miller
【单选题】
Of the following, is NOT Nathaniel Hawthorne’s work.
A. A. The Scarlet Letter
B. B. The House of the Seven Gables
C. C. The Marble Faun
D. D. Nature
【单选题】
is regarded as “the father of American literature”.
A. A. James Fennimore Cooper
B. B. Ralph Waldo
C. C. Thomas Jefferson
D. D. Washington Irving
【单选题】
Of the following writers, are from the Colonial and Revolutionary Periods.
A. A. Benjamin Franklin & Edgar Ellen Poe
B. B. Edgar Ellen Poe & Jonathan Edwards
C. C. Benjamin Franklin & Jonathan Edwards
D. D. Edgar Ellen Poe & Washington Irving
【单选题】
The National Day of the United States falls on .
A. A. June 4th
B. B. July 4th
C. C. June 14th
D. D. July 14th
【单选题】
Of the following, is NOT among the three major radio and TV networks in America.
A. A. the National Broadcasting System (NBS)
B. B. the Public Broadcasting Service (PBS)
C. C. the Columbia Broadcasting System (CBS)
D. D. the American Broadcasting System (ABS)
【单选题】
is sold especially to the upper or upper-middle class and it has a reputation for its serious attitude and great bulk.
A. A. The Washington Post
B. B. The New York Times
C. C. Los Angeles Times
D. D. New York Daily News
【单选题】
Of the following universities, has NOT cultivated any American President yet.
A. A. Harvard University
B. B. Massachusetts Institute of Technology
C. C. Princeton University
D. D. Yale University
【单选题】
To get a bachelor’s degree, all undergraduate students are required to do the following except .
A. A. attending lectures and completing assignments
B. B. passing examinations
C. C. working for communities
D. D. earning a certain number of credits
【单选题】
Of the following, is NOT the responsibility of the board of trustees in U. S. institutions.
A. A. choosing the president
B. B. establishing policies for administrators and faculty
C. C. approving budget and other financial project
D. D. decide which student to enroll
【单选题】
Of the following, are NOT among the categories of American higher education.
A. A. universities and colleges
B. B. research institutions
C. C. technical institutions
D. D. community colleges
【单选题】
Higher education in the United States began with the founding of
A. A. Yale University
B. B. Harvard University
C. C. Princeton University
D. D. New York University
【单选题】
Of the following subjects, are NOT offered to elementary school students.
A. A. mathematics and languages
B. B. politics and business education
C. C. science and social studies
D. D. music and physical education
【单选题】
Formal education in the United States consists of , secondary and higher education.
A. A. kindergarten
B. B. public
C. C. elementary
D. D. private
【单选题】
At present, U. S. exports account for of the world’s total.
A. A. 10%
B. B. 15%
C. C. 20%
D. D. 25%
【单选题】
is not one of the three giants in American automobile industry.
A. A. Ford
B. B. General Motors
C. C. Chrysler
D. D. American Motors
【单选题】
The following statements are all true except .
A. A. Agribusinesses reflect the big, corporate nature of many farm enterprises.
B. B. Agribusinesses maintain a balanced trade pattern between agricultural imports and exports.
C. C. Agribusinesses range from one-family corporations to multinational firms.
D. D. Agribusinesses include a variety of farm businesses and structures.
【单选题】
About of American crops are for export.
A. A. half
B. B. one third
C. C. one fourth
D. D. one fifth
【单选题】
President Johnson tried to build a “Great Society” by introducing various programs like the following except .
A. A. Medicare
B. B. Food Stamps
C. C. Education Initiatives
D. D. Unemployment Pension
【单选题】
The following inventions took place during the “second indThe following inventions took place during the “second industrial revolution” except .
A. A. typewriter
B. B. telephone
C. C. electric light
D. D. refrigerator
【单选题】
The first National Bank of the United States was established with the urge of .
A. A. George Washington
B. B. Thomas Jefferson
C. C. Andrew Jackson
D. D. Alexander Hamilton
【单选题】
Chartered companies were NOT granted the by the British King or Queen.
A. A. political authority
B. B. economic rights
C. C. judicial authority
D. D. diplomatic authority
【单选题】
The modern American economy progressed from to , and eventually, to .
A. A. colonial economy, handcraft economy, industrial economy
B. B. farming economy, handcraft economy, industrial economy
C. C. colonial economy, farming economy, industrial economy
D. D. handcraft economy, farming economy, industrial economy
【单选题】
America produces a major portion of the world’s products in the following fields except .
A. A. machinery
B. B. automobiles
C. C. ore
D. D. chemicals
【单选题】
The President is directly voted into office by .
A. A. all citizens of America
B. B. the citizens over 18 years old
C. C. electors elected by the voters
D. D. the senators and representatives
【单选题】
The Supreme Court is composed of justices.
A. A. six
B. B. seven
C. C. eight
D. D. nine
【单选题】
The terms for a Senator and Representative are and years respectively.
A. A. two, four
B. B. two, three
C. C. two, six
D. D. six, two
【单选题】
According to the Constitution, a candidate for President must be .
A. A. at least 35 years old
B. B. at least a 14 years’ resident of the United States
C. C. born in America
D. D. all of the above
【单选题】
The following except are all powers of the President.
A. A. vetoing any bills passed by Congress
B. B. appointing federal judges when vacancies occur
C. C. making laws
D. D. issuing executive orders
【单选题】
All the following except cannot make legislative proposal.
A. A. the Senator
B. B. the Representative
C. C. the Secretary of State
D. D. the President
