东大19春学期《测试技术基础》在线作业3参考答案

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东大19春学期《分析化学》在线作业3【标准答案】

(单选题)1: 在Sn2+、Fe2+的混合溶液中，欲使Sn2+氧化为Sn4+，而Fe2+不被氧化，应选择的氧化剂是（）。

（已知Φ0Sn4+/ Sn2+=0.15V，Φ0Fe3+/ Fe2+=0.77V）A: KIO3（Φ0IO3-/I2=1.20V）      B: H2O2（Φ0H2O2/2OH-=0.88V）C: HgCl2（Φ0HgCl2/Hg2Cl2=0.63V） D: SO32-（Φ0SO32-/S=-0.66V）E: S（Φ0S/H2S=0.14V）正确答案:(单选题)2: 指出下列叙述中错误的结论（）A: 络合剂的酸效应使络合物的稳定性降低B: 金属离子的水解效应使络合物的稳定性降低C: 辅助络合效应使络合物的稳定性降低D: 各种副反应均使络合物的稳定性降低正确答案:(单选题)3: N离子共存时，可以用控制溶液酸度的方法准确滴定M离子的条件式为（）A: lgK′MY-lgK′NY≥5       B:   lgcMKMY-lgcNKNY≥5 C: lgcMK′MY-lgcNK′NY≥5    D: lgcMKMY-lgcNK′NY≥5   E: lgcMK′MY-lgcNKNY≥5正确答案:(单选题)4: 用EDTA滴定Mg2+，采用铬黑T为指示剂，少量Fe3+的存在将导致（）A: 终点颜色变化不明显以致无法确定终点B: 在化学计量点前指示剂即开始游离出来，使终点提前C: 使EDTA与指示剂作用缓慢,终点延长D: 与指示剂形成沉淀,使其失去作用正确答案:(单选题)5: Ag-AgCl参比电极的电极电位取决于电极内部溶液中（）A: Ag+活度  B: Cl-活度C: AgCl活度 D: Ag+和Cl-活度之和正确答案:(单选题)6: 准确滴定金属离子的条件一般为（）A: lgcK′MY≥8  B: lgK′MY≥6  C: lgcKMY≥6 D: lgcK′MY≥7  E: lgcK′MY≥6正确答案:(单选题)7: 某指示剂的KHIn=1.0×10-4，则其理论变色范围为（）A: pH3~4  B: pH4~6   C: pH3~5  D: pH4~5   E: pH2~6正确答案:(单选题)8: 在滴定分析中，所用试剂含有微量被测组分，应该进行（）A: A）、对照试验      B:  B）、空白试验      C:  C）、仪器校准  D: D）、方法校正       E: E）、增加测定次数正确答案:(单选题)9: 原子吸收分光光度法中，所谓的谱线轮廓是（）A: 吸收系数Kν随频率ν的变化  B: 吸收系数Kν随波长λ的变化C: 谱线强度随频率ν的变化      D: 谱线强度随波长λ的变化正确答案:(单选题)10: 下列各项定义中不正确的是（）A: A）、绝对误差是测定值与真值之差 B: B）、相对误差是绝对误差在真值中所占的百分比C: C）、偏差是指测定值与平均值之差  D: D）、总体平均值就是真值正确答案:(判断题)11: 色谱的塔板理论提出了衡量色谱柱效能的指标，速率理论则指出了影响柱效的因素。

北航《测试技术基础》在线作业三满分答案

北航《测试技术基础》在线作业三一、单选题（共 10 道试题，共 30 分。

）1. 要使RC低通滤波器的通带加宽，则RC值应（）。

A. 增加B. 减少C. 不变D. 先增加后减少-----------------选择：B2. 傅氏级数中的各项系数是表示各谐波分量的（）。

A. 相位B. 周期C. 振幅D. 频率-----------------选择：C3. 金属丝应变片在测量构件的应变时，电阻的相对变化主要由（）来决定的。

A. 贴片位置的温度变化B. 电阻丝几何尺寸的变化C. 电阻丝材料的电阻率变化D. 以上都不对-----------------选择：B4. 自相关函数是一个（）函数。

A. 奇B. 偶C. 非奇非偶D. 三角-----------------选择：B5. 时域信号，当持续时间延长时，则频域中的高频成分（）。

A. 不变B. 增加C. 减少D. 变化不定-----------------选择：C6. 为提高电桥的灵敏度，可采取的方法是（）。

A. 半桥双臂各串联一片电阻应变片B. 半桥双臂各并联一片电阻应变片C. 适当提高电桥的电源电压D. 增大应变片的初始电阻值-----------------选择：C7. 复杂的信号的周期频谱是（）。

A. 离散的B. 连续的C. δ函数D. sinc函数-----------------选择：A8. 测试装置的脉冲响应函数与它的频率响应函数间的关系是（）。

A. 卷积B. 傅氏变换对C. 拉氏变换对D. 微分-----------------选择：B9. 把连续时间信号进行离散化时产生混叠的主要原因是（）。

A. 记录时间太长B. 采样间隔太宽C. 记录时间太短D. 采样间隔太窄-----------------选择：B10. 二阶系统的阻尼率ξ越大，则其对阶跃输入时的响应曲线超调量（）。

A. 越大B. 越小C. 不存在D. 无关-----------------选择：B北航《测试技术基础》在线作业三单选题判断题多选题二、判断题（共 10 道试题，共 30 分。

东北大学19秋学期《测试技术基础》在线平时作业31-答案

D.D
参考选择:B
二、判断题(共10道试题,共50分)
1.判断题中间导体定律指出，在热电偶回路中，只要接入的第三导体两端温度不同，则对回路的总的热电势没有影响。
A.错误
B.正确
参考选择:A
2.正弦信号的自相关函数保留了信号的幅值信息和频率信息，但是失去了相位的信息。（）
A.错误
B.正确
参考选择:B
3.非确定性信号又称为随机信号，是有法用明确的数学关系式表达的信号。
B.B
C.C
D.D
参考选择:C
8.选择题
A.A
B.B
C.C
D.D
参考选择:C
9.当某些晶体沿一定方向受外力作用而变形时，其相应的两个相对表面产生极性相反的电荷，去掉外力时电荷消失，这种现象称为（）。
A.压阻效应
B.压敏效应
C.逆压电效应
D.正压电效应
参考选择:D
10.线性系统输入输出
A.A
B.B
C.C
10.判断题8为了避免混迭以便采样后仍能准确地恢复原信号，采样频率fS必须大于信号最高频率fC的0.5倍，即fS＞0.5fC，这就是采样定理。（）
A.错误
B.正确
参考选择:A
6.传感器的功能是将被测信息转换成某种电信号的器件。它包括敏感器和转换器两部分。
A.错误
B.正确
参考选择:B
7.各类瞬变信号是能量信号。
A.错误
B.正确
参考选择:B
8.概率密度函数曲线下的面积等于2。
A.错误
B.正确
参考选择:A
9.判断题1概率分布函数是概率密度函数的导数。（）
A.错误
B.正确
参考选择:A
【东北大学】19秋学期《测试技术基础》在线作业3

测试技术基础习题答案-

相位为：φ2－φ1=φ(ω1) →φ2=φ(ω1)+ φ1=-82.875º
其输出信号为：y2(t)=0.496sin(4t-82.875º)
所以，x(t)为输入信号时，输出信号为：
y(t)= y1(t)+ y2(t)= 0.78sin(4t-38.66º)+0.05sin(4t-82.875º)
3-25 用一阶系统对100Hz正弦信号进行测量，如果要求振幅误差在5%以内，则时间常数应取多少？如用具有该时间常数的同一系统作50Hz正弦信号的测试，问此时的振幅误差和相位差是多少？
半桥双臂接法时，
全桥法时，
图略。
5-23以阻值，灵敏度S=2的电阻应变片与阻值的固定电阻组成电桥，供桥电压为4V，并假定负载电阻无穷大，当应变片上的应变分别为1和1000时，半桥单臂、半桥双臂及全桥的输出电压，并比较三种情况下的灵敏度。
解：1）应变为1με时，
半桥单臂时，输出电压：
半桥双臂时，输出电压：
其输出信号为：y2(t)=0.1572sin(4t-80.96º)
可以看出，对于信号，其幅值由1变为0.537,相位由0 º变为-57.52º；对于信号，其幅值由1变为0.1572,相位由0 º变为-80.96º；信号的幅值和相位变化大于信号的幅值和相位的变化。
3-31 对一个二阶系统输入单位阶跃信号后，测得响应中产生的第一个过冲量M的数值为1.5，同时测得其周期为6.28s。设已知装置的静态增益为3，试求该装置的传递函数和装置在无阻尼固有频率处的频率响应。
相位为：φ2－φ1=φ(ω1) →φ2=φ(ω1)+ φ1=-57.52º；其输出信号为：y1(t)=0.537sin(t-57.52º)
当输入信号为x2(t)= sin4t时，其角频率ω2=4，幅值A2=1，初相位φ1=0；则

东大19春学期《计算机网络》在线作业3【标准答案】

(单选题)1: 网卡工作在OSI七层模型中的（）层。

A: 物理层B: 数据链路层C: 网络层D: 运输层正确答案:(单选题)2: 接收窗口和发送窗口都等于1的协议是（）。

A: 停止等待协议B: 连续ARQ协议C: PPP协议D: 选择重传ARQ协议正确答案:(单选题)3: 无论是SLIP还是PPP协议都是（）协议。

A: 物理层B: 数据链路层C: 网络层D: 传输层正确答案:(单选题)4: 在一个 Ethernet 中，有 A、B、C、D 四台主机，如果 A 向 B 发送数据，那么（）。

A: 只有B可以接收到数据B: 数据能够瞬间到达BC: 数据传输存在延迟D: 其它主机也可以同时发送数据正确答案:(单选题)5: 网络中用集线器或交换机连接各计算机的这种拓扑结构属于（）。

A: 总线结构B: 星型结构C: 环形结构D: 网状结构正确答案:(单选题)6: 普通的长途电话采用的交换方式为（）。

A: 分组交换B: 电路交换C: 报文交换D: 信元交换正确答案:(单选题)7: 对等层实体之间采用（）进行通信。

A: 服务B: 连接C: 协议D: 信令正确答案:(单选题)8: 检查网络连通性的应用程序是：（）。

A: PINGB: ARPC: BINDD: DNS正确答案:(单选题)9: TCP使用（）进行流量控制。

A: 三次握手B: 自动重发机制C: 窗口控制机制D: 端口机制正确答案:(单选题)10: 下列哪一种说法是正确的（）。

A: 集线器具有对信号整形的功能B: 集线器具有信息过滤功能C: 集线器具有路径选择功能D: 集线器具有交换功能正确答案:(单选题)11: 局域网参考模型一般不包括（）。

A: 网络层B: 物理层C: 数据链路层D: 介质访问控制层正确答案:(单选题)12: 各种网络在物理层互连时要求（）。

A: 数据传输率和链路协议都相同B: 数据传输率相同，链路协议可不相同C: 数据传输率可不同，链路协议相同D: 数据传输率和链路协议都可不同正确答案:(单选题)13: 以太网交换机在网络帧碎片较多时，工作在（）状态下效率最高。

东大19春学期《大学英语(一)》在线作业3【标准答案】

(µ¥Ñ¡Ìâ)1: If you want to learn English well, don’t forget intensive reading and _____ reading.A: extendedB: extensiveC: wideD: externalÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)2: He       excited at the good newsA: lookB: appearsC: disappearD: feelÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)3:When I got to his home, he ____ ____ for an hour.A: had leftB: leftC: had been awayD: has been awayÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)4: He left the spot immediately, afraid of being ____ in the car accident.A: connectedB: takenC: seatedD: involvedÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)5: Will there be a strong wind ____ the north ______ the Huanghe River ?A:  to... ofB: to... offC: at... ofD: on… offÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)6: Scientific discoveries are often applied_____ industrial production methods.A: for B: with C: to D: onÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)7: I asked the bank for a _____.A: loafB: loadC: loanD: loamÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)8: The teacher required that all the assignments _____finished before this weekend.A: would beB: wereC: beD: are toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)9:Everyone except Tom and John ______  there when the meeting began.A: isB: wasC: areD: wereÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)10: A good habit can make our mental health in      with physical health.A: concernB: connectionC: compareD: tuneÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)11:  May she _______ with you?A: comeB: comesC: comingD: cameÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)12: Which is the best approach _____ the tunnel?A: toB: withC: besidesD: towardsÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)13:He could_____ neither French or German,&n bsp;so I____ with him in English.A: speak, talkedB: talk, toldC: say, spokeD: tell, talkedÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)14:Don’t spend _______ time on compute r games.A: too muchB: much tooC: too manyD: many tooÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)15: Many girls like __________ skirts in summer.A: wearingB: dressingC: inD: putting onÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)16:Look! Lily with her sister _________&nbsp ;a kite on the playground.A: is flyingB: are flyingC: flyingD: flyÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)17: My home is about ________ from my school.A: 15 minutesB: minute's rideC: 20 minutes by bikeD: 15- minute's on foot.ÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)18:The policeman stopped ________, but he&nb sp;_______ no sound.A: hearing,heardB: listening,listenedC: to listen,heardD: listening to,listened toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)19:  He walked ________ fast for us ________catch up with. A: so, thatB: such, thatC: enough, toD: too,toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)20:  He failed the exam because he didn’t have      time(×ã¹»µÄÊ±¼ä) to prepare.A: rightB: spareC: adequateD: ownÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)21: The evidence found in this search is always incomplete and _____, it is also frequently partial.A: scatter  B: scattered C: scattering D:  scattered toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)22: The museum has some new _____from India.A: exhibit B: exhibition C: exhibits D: exhibitionsÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)23: The organization performed an important _____ in protectingthe rights of children.A: functionB: fictionC: fractionD: frictionÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)24: ---He can swim. ---_______ .A: So I canB: So can IC: I so canD: Can I soÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)25:  He ________ living in the country to the city. A: likesB: prefersC: enjoysD: lovesÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)26: What kind of music is your_____?A: favorableB: favoriteC: favorD: fateÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)27: --Must we finish our homework now?--No, you ______. You _______ finish it after school.A: needn't , mayB: mustn't , mayC: can't , canD:  needn't , mustÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)28: -- You seem to like sweets. --________ . I buy sweets every week.¡¡¡¡ A: So do IB: So I doC: So am ID: So I amÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)29: It is not _____to quarrel with your boss.A: worthyB: worthC: valueD: valuableÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)30: --Would you give me some water?  --____________.A: Yes, I wouldB: CertainlyC: No, thanksD: Yes,pleaseÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)31:     He was struggling to tie his shoes.I was struggling with whether I should help him.    I did, and he was grateful.“Thank you,” he said.“I’m glad I could help. I just thought it would be easier for me to reach,” I said.    He was a disabled man, and forced to look down most of the time. His arms and legs were twisted terribly, and he couldn’t do what the rest of us would consider easy tasks. He always managed to look up to see how you reacted to his words, however. He had a big smile, making me feel comfortable.     I was still on my knees by his wheelchair.“ Nice shoes,” he said.“Thanks. No one ever complimented me on them before,” I said.“No one has the same view of the world as I do,” he replied.“Tell me about the world as you see it,” I said smiling.“Most people can see if someone is comfortable with them or not in their eyes. I see it in their feet.” he said. “If people keep moving their feet, I just let them go, because I know they’re impatient with me. I don’t want to make people uncomfortable.“What about me? I asked.“I could see your compassion. And then you came down to my level. I was the one who was nervous.” he said. “I don’t normally have someone look me in the eye.”“They don’t know what they’re missing,” I told him.“My old face is nothing to brag about.” he said.“But that smile is so big.”    Yes, and it’s not only a big smile but an attitude.ÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)32:     My summer hols wr CWOT. B4. we usd 2 go 2 NY 2C my bro, his GF £¦ thr 3 : -@ kids FTF. ILNY, its gr8.    Can you understand this sentence? If you can’t, don't feel too bad: neither could the middle school teacher in England who received this as homework. This is Netspeak: the language of computerized communication found on Internet or cellphones. To newcomers, it ran like a completely foreign language. So, what is the "translation" of the sentence above? My summer holidays were a complete waste of time. Before, we used to go to New York to see my brother, his girlfriend, and their three screaming kids face to face.I love New York; it’s great.    Schoolteachers and parents say this new form of writing is harming the English language. Increasing spelling and grammatical mistakes can be seen in students' writing. They fear the language could become corrupted (ÃæÄ¿È«·ÇµÄ).    Everyone should just relax, say linguists (ÓïÑÔÑ§¼Ò). They believe Netspeak is in fact more of a good thing. David Crystal, from the University of Wales, argues that Netspeak and Internet create a new language use and the almost lost art of diary writing has been picked up again. Geoffrey Nunberg, from Stanford University, agrees. "People get better at writing by writing," he says, “Kids who are now doing text messaging, e-mail, and instant messages will write at least as well as, and possibly better than their parents."    Linguist James Milroy says, for centuries, it is believed without exception that young people are harming the language. And you can bet your bottom dollar that when today's teenagers become tomorrow's parents, they too will think this way, Milroy argues that languages do not and cannot become "corrupted"; they simply change to meet the new needs.    However, Netspeakers do agree that it is important to teach young people how to speak and write Standard English. Cynthia McVey says, "I can understand Netspeak worries teachers and it's important that they get across to their pupils that text messaging is for fun, but that learning to write proper English is a must for their future.”    Perhaps we should give teenagers a little more trust anyway. Erin, age 12, says, "I wouldn't use text language in my homework. Texting is just for fun."ÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)33:     What might the future be like? Here are some predictions: things to come, things to go.     The Spring Festival, the most important Chinese holiday when everyone returns home, has caused headaches for millions of Chinese. More than 2 billion people travel at the same time, making getting travel ticketsand the journey difficult. But in 28 years, Spring Festival travel may not be a problem at all. China plans to build more than 120,000 kilometers of railway and a fast transportation network that will serve 90% of the population by 2020. And because most of China will be cities, people will not have to go to other places to find a job, so it will no longer be a problem.    Newspaper will come to an end in 2043. In the future, digital newspapers will be sent to personal web tools through Internet. Readers can discuss topics with journalists and editors. Information will move faster.     Oil is running out faster than expected. But scientists have found something else for oil as fuel. Coal, natural gas, solar power, nuclear power and even water can take the place of oil as sources of energy.     Schools will go electronic. Computers will be important and popular among the students. Everything will be in the computer and students will not need to bring books to school. They will find information on the Internet. A computer will be the students’ library, schoolbag and connection to the outside world. There will be robot teachers, they will check homework on computers and communicate with the students’ parents through e-mail. And school buses will be like spaceships, comfortable and safe.ÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)34:     More and more people like bicycling and it is no surprise. It is fun, healthy and good for the environment. Maybe that’s why there are 1.4 billion bicycles and only 400 million cars on roads worldwide today. Bikes can take you almost anywhere, and there is no oil cost!    Get on a bicycle and ride around your neighborhood. You may discover something new all around you. Stopping and getting off a bike is easier than stopping and getting out of your car. You can bike to work and benefit (ÊÜÒæ) from the enjoyable exercise without polluting the environment. You don’t even have to ride all the way.    Folding (ÕÛµþ) bikes work well for people who ride the train. Just fold the bike and take it with you. You can do the same on an airplane. A folding bike can be packed in a suitcase. You can also take a common bike with you when you fly. But be sure to look for information by getting on airline websites. Not all airlines are bicycle-friendly to travelers.Health Benefits of Bicycling:? It helps to prevent heart diseases.? Bicycling helps to control your weight.     A 15-minute bike ride to and from work three times a week burns off five kilos of fat in a year.? Bicycling can improve your mood.      Exercise like bicycling has been shown to make people feel better, more relaxed andself-confident.? Bicycling is healthier than driving.ÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)1: If you want to learn English well, don’t forget intensive reading and _____ reading.A: extendedB: extensiveC: wideD: externalÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)2: He       excited at the good newsA: lookB: appearsC: disappearD: feelÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)3:When I got to his home, he ____ ____ for an hour.A: had leftB: leftC: had been awayD: has been awayÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)4: He left the spot immediately, afraid of being ____ in the car accident.A: connectedB: takenC: seatedD: involvedÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)5: Will there be a strong wind ____ the north ______ the Huanghe River ?A:  to... ofB: to... offC: at... ofD: on… offÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)6: Scientific discoveries are often applied_____ industrial production methods.A: for B: with C: to D: onÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)7: I asked the bank for a _____.A: loafB: loadC: loanD: loamÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)8: The teacher required that all the assignments _____finished before this weekend.A: would beB: wereC: beD: are toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)9:Everyone except Tom and John ______  there when the meeting began.A: isB: wasC: areD: wereÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)10: A good habit can make our mental health in      with physical health.A: concernB: connectionC: compareD: tuneÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)11:  May she _______ with you?A: comeB: comesC: comingD: cameÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)12: Which is the best approach _____ the tunnel?A: toB: withC: besidesD: towardsÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)13:He could_____ neither French or German,&n bsp;so I____ with him in English.A: speak, talkedB: talk, toldC: say, spokeD: tell, talkedÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)14:Don’t spend _______ time on compute r games.A: too muchB: much tooC: too manyD: many tooÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)15: Many girls like __________ skirts in summer.A: wearingB: dressingC: inD: putting onÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)16:Look! Lily with her sister _________&nbsp ;a kite on the playground.A: is flyingB: are flyingC: flyingD: flyÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)17: My home is about ________ from my school.A: 15 minutesB: minute's rideC: 20 minutes by bikeD: 15- minute's on foot.ÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)18:The policeman stopped ________, but he&nb sp;_______ no sound.A: hearing,heardB: listening,listenedC: to listen,heardD: listening to,listened toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)19:  He walked ________ fast for us ________catch up with. A: so, thatB: such, thatC: enough, toD: too,toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)20:  He failed the exam because he didn’t have      time(×ã¹»µÄÊ±¼ä) to prepare.A: rightB: spareC: adequateD: ownÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)21: The evidence found in this search is always incomplete and _____, it is also frequently partial.A: scatter  B: scattered C: scattering D:  scattered toÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)22: The museum has some new _____from India.A: exhibit B: exhibition C: exhibits D: exhibitionsÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)23: The organization performed an important _____ in protecting the rights of children.A: functionB: fictionC: fractionD: frictionÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)24: ---He can swim. ---_______ .A: So I canB: So can IC: I so canD: Can I soÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)25:  He ________ living in the country to the city. A: likesB: prefersC: enjoysD: lovesÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)26: What kind of music is your_____?A: favorableB: favoriteC: favorD: fateÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)27: --Must we finish our homework now?--No, you ______. You _______ finish it after school.A: needn't , mayB: mustn't , mayC: can't , canD:  needn't , mustÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)28: -- You seem to like sweets. --________ . I buy sweets every week.¡¡¡¡ A: So do IB: So I doC: So am ID: So I amÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)29: It is not _____to quarrel with your boss.A: worthyB: worthC: valueD: valuableÕýÈ·´ð°¸:(µ¥Ñ¡Ìâ)30: --Would you give me some water?  --____________.A: Yes, I wouldB: CertainlyC: No, thanksD: Yes,pleaseÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)31:     He was struggling to tie his shoes.I was struggling with whether I should help him.    I did, and he was grateful.“Thank you,” he said.“I’m glad I could help. I just thought it would be easier for me to reach,” I said.    He was a disabled man, and forced to look down most of the time. His arms and legs were twisted terribly, and he couldn’t do what the rest of us would consider easy tasks. He always managed to look up to see how you reacted to his words, however. He had a big smile, making me feel comfortable.     I was still on my knees by his wheelchair.“ Nice shoes,” he said.“Thanks. No one ever complimented me on them before,” I said.“No one has the same view of the world as I do,” he replied.“Tell me about the world as you see it,” I said smiling.“Most people can see if someone is comfortable with them or not in their eyes. I see it in their feet.” he said. “If people keep moving their feet, I just let them go, because I know they’re impatient with me. I don’t want to make people uncomfortable.“What about me? I asked.“I could see your compassion. And then you came down to my level. I was the one who was nervous.” he said. “I don’t normally have someone look me in the eye.”“They don’t know what they’re missing,” I told him.“My old face is nothing to brag about.” he said.“But that smile is so big.”    Yes, and it’s not only a big smile but an attitude.ÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)32:     My summer hols wr CWOT. B4. we usd 2 go 2 NY 2C my bro, his GF £¦ thr 3 : -@ kids FTF. ILNY, its gr8.    Can you understand this sentence? If you can’t, don't feel too bad: neither could the middle school teacher in England who received this as homework. This is Netspeak: the language of computerized communication found on Internet or cellphones. To newcomers, it ran like a completely foreign language. So, what is the "translation" of the sentence above? My summer holidays were a complete waste of time. Before, we used to go to New York to see my brother, his girlfriend, and their three screaming kids face to face.I love New York; it’s great.    Schoolteachers and parents say this new form of writing is harming the English language. Increasing spelling and grammatical mistakes can be seen in students' writing. They fear the language could become corrupted (ÃæÄ¿È«·ÇµÄ).    Everyone should just relax, say linguists (ÓïÑÔÑ§¼Ò). They believe Netspeak is in fact more of a good thing. David Crystal, from the University of Wales, argues that Netspeak and Internet create a new language use and the almost lost art of diary writing has been picked up again. Geoffrey Nunberg, from Stanford University, agrees. "People get better at writing by writing," he says, “Kids who are now doing text messaging, e-mail, and instant messages will write at least as well as, and possibly better than their parents."    Linguist James Milroy says, for centuries, it is believed without exception that young people are harming the language. And you can bet your bottom dollar that when today's teenagers become tomorrow's parents, they too will think this way, Milroy argues that languages do not and cannot become "corrupted"; they simply change to meet the new needs.    However, Netspeakers do agree that it is important to teach young people how to speak and write Standard English. Cynthia McVey says, "I can understand Netspeak worries teachers and it's important that they get across to their pupils that text messaging is for fun, but that learning to write proper English is a must for their future.”    Perhaps we should give teenagers a little more trust anyway. Erin, age 12, says, "I wouldn't use text language in my homework. Texting is just for fun."ÕýÈ·´ð°¸:(ÔÄ¶ÁÀí½â)33:     What might the future be like? Here are some predictions: things to come, things to go.    。

(完整word版)《测试技术基础》复习题及答案

复习题第一章信号及其描述（一）填空题1、测试的基本任务是获取有用的信息，而信息总是蕴涵在某些物理量之中，并依靠它们来传输的。

这些物理量就是，其中目前应用最广泛的是电信号。

2、信号的时域描述，以为独立变量；而信号的频域描述，以为独立变量。

3、周期信号的频谱具有三个特点：，，。

4、非周期信号包括信号和信号。

5、描述随机信号的时域特征参数有、、。

6、对信号的双边谱而言，实频谱（幅频谱）总是对称，虚频谱（相频谱）总是对称。

（二）判断对错题（用√或×表示）1、各态历经随机过程一定是平稳随机过程。

（）2、信号的时域描述与频域描述包含相同的信息量。

（）3、非周期信号的频谱一定是连续的。

（）4、非周期信号幅频谱与周期信号幅值谱的量纲一样。

（）5、随机信号的频域描述为功率谱。

（）（三）简答和计算题1、求正弦信号t x t x ωsin )(0=的绝对均值μ|x|和均方根值x rms 。

2、求正弦信号)sin()(0ϕω+=t x t x 的均值x μ，均方值2x ψ，和概率密度函数p(x)。

3、求指数函数)0,0()(≥>=-t a Ae t x at 的频谱。

4、求被截断的余弦函数⎩⎨⎧≥<=T t T t t t x ||0||cos )(0ω的傅立叶变换。

5、求指数衰减振荡信号)0,0(sin )(0≥>=-t a t e t x at ω的频谱。

第二章测试装置的基本特性（一）填空题1、某一阶系统的频率响应函数为121)(+=ωωj j H ，输入信号2sin )(t t x =，则输出信号)(t y 的频率为=ω ，幅值=y ，相位=φ 。

2、试求传递函数分别为5.05.35.1+s 和2224.141nn n s s ωωω++的两个环节串联后组成的系统的总灵敏度。

3、为了获得测试信号的频谱，常用的信号分析方法有、和。

东大19春学期《测试技术基础》在线作业3

------------------------------------------------------------------------------------------------------------------------------(单选题)1: 传感器的动态特性越好，说明传感器的响应在被测频率范围内（）。

A: 精度越高B: 精度越差C: 对被测信号的反应能力越快D: 对被测信号的反应能力越慢正确答案:(单选题)2: 有一测力电桥A: AB: BC: CD: D正确答案:(单选题)3: endA: AB: BC: CD: D正确答案:(单选题)4: 当某些晶体沿一定方向受外力作用而变形时，其相应的两个相对表面产生极性相反的电荷，去掉外力时电荷消失，这种现象称为（）。

A: 压阻效应B: 压敏效应C: 逆压电效应D: 正压电效应正确答案:(单选题)5: xua选择题A: AB: BC: CD: D正确答案:(单选题)6: 选择题A: AB: BC: CD: D正确答案:(单选题)7: 满足不真测试条件的测试系统，其幅频特性和相频特性为（）A: AB: BC: CD: D正确答案:------------------------------------------------------------------------------------------------------------------------------(单选题)8: 傅立叶变换性质A: AB: BC: CD: D正确答案:(单选题)9: 将若矩形窗函数A: AB: BC: CD: D正确答案:(单选题)10: endA: AB: BC: CD: D正确答案:(判断题)11: 椭圆齿轮流量计是借助于固定的容积来计量流量的，与流体的流动状态及粘度有关。

（）A: 错误B: 正确正确答案:(判断题)12: 当金属板置于变化着的磁场中时，或者在磁场中运动时，在金属板上产生感应电流，这就是电感式传感器的工作原理A: 错误B: 正确正确答案:(判断题)13: 周期信号与随机信号的互相关函数为1。

东大19秋学期《模拟电子技术基础Ⅰ》在线平时作业3参考答案

19秋学期《模拟电子技术基础Ⅰ》在线平时作业3
试卷总分:100 得分:100
一、单选题 (共 15 道试题,共 60 分)
1.互补输出级采用共集形式是为了使（）。

A.电压放大倍数大
B.不失真输出电压大
C.带负载能力强
答案:C
2.开关型直流电源比线性直流电源效率高的原因是
A.输出端有LC滤波电路
B.调整管工作在开关状态
C.可以不用电源变压器
答案:B
3.功率放大电路的最大输出功率是在输入电压为正弦波时，输出基本不失真情况下负载上获得的最大（）。

A.直流功率
B.有功功率
C.平均功率
D.交流功率
答案:D
4.为增大电压放大倍数，集成运放的中间级多采用（）。

A.共集放大电路
B.共射放大电路
C.共基放大电路
答案:B
5.负载需5A电流驱动的放大器，集成运放应选用（）。

A.高阻型
B.高速型
C.通用型
D.大功率型
答案:D
6.在长尾式的差分放大电路中，Re的主要作用是（）。

A.提高差模电压放大倍数
B.抑制零漂
C.增大差模输入电阻
答案:B
7.为了减小放大电路的输出电阻，应引入（）负反馈
A.电压
B.电流
C.串联
D.并联。

东大19春学期《中国法制史》在线作业3

------------------------------------------------------------------------------------------------------------------------------ (单选题)1: 凌迟刑作为法定刑广泛使用始于( )。

A: 唐B: 宋C: 明D: 清正确答案:(单选题)2: 关于西周法制的表述,下列哪一选项是正确的?( )A: 周初统治者为修补以往神权政治学说的缺陷，提出了“德主刑辅，明德慎罚”的政治法律主张B: 《后汉书·陈宠传》称西周时期的礼刑关系为“礼之所去，刑之所取，失礼则入刑，相为表里”C: 西周的借贷契约称为“书约”，法律规定重要的借贷行为都须订立书面契约D: 西周时期在宗法制度下已形成子女平均继承制正确答案:(单选题)3: 刑法中的“折杖法”规定最早出现在( )。

A: 唐朝B: 宋朝C: 元朝D: 明朝正确答案:(单选题)4: 唐代的法律形式主要是( )。

A: 礼、刑、誓、诰B: 律、令、科、比C: 律、令、格、式D: 律、例、会典、章程正确答案:(单选题)5: 唐律规定,在斗杀过程中,错杀旁人的行为为( )。

A: 斗杀B: 戏杀C: 误杀D: 过失杀正确答案:(单选题)6: 中国历史上最后一部封建性质的成文法典是( )。

A: 《大清律例》B: 《大清律集解》C: 《大清律集解附例》D: 《大清现行刑律》正确答案:(单选题)7: 西周商品经济发展促进了民事契约关系的发展。

《周礼》载:“听买卖以质剂”。

汉代学者郑玄解读西周买卖契约形式:“大市谓人民、牛马之属,用长券;小市为兵器、珍异之物,用短券。

”对此,下列哪一说法是正确的?( )A: 长券为“质”，短券为“剂”B: “质”由买卖双方自制，“剂”由官府制作------------------------------------------------------------------------------------------------------------------------------ C: 契约达成后，交“质人”专门管理D: 买卖契约也可采用“傅别”形式正确答案:(单选题)8: 我国第一次公布成文法的人是春秋时郑国的( )。

东北大学19春学期《软件工程与UML建模》在线作业3满分答案

东大19春学期《软件工程与UML建模》在线作业3
试卷总分:100 得分:100
[试题1]、原型的优点不包括（）
A、对设计人员水平及开发环境要求不高
B、可及早为用户提供有用的产品
C、可及早发现问题，随时纠正错误
D、可减少技术、应用的风险
正确选择是:A
[试题2]、判定表和判定树是数据流图中用以描述加工的工具，它常描述的对象是（）
A、逻辑判断
B、层次分解
C、操作条目
D、组合条件
正确选择是:D
[试题3]、在实际的开发过程中，纠正了程序中的错误之后，还应该选择部分或全部原先已测试过的用例，对修改后的程序重新测试，这种测试称为（）。

A、验收测试
B、强度测试
C、系统测试
D、回归测试
正确选择是:D
[试题4]、软件的集成测试工作最好由（）承担，以提高集成测试的效果。

A、该软件的设计人员
B、该软件开发组的负责人
C、该软件的编程人员
D、不属于该软件开发组的软件设计人员
正确选择是:D
[试题5]、下面哪一项不是基本的软件需求（）
A、功能需求
B、性能需求
C、环境需求
D、市场需求
正确选择是:D
[试题6]、下面那个量不属于软件度量的范围（）。

东大19春学期《安全检测及仪表》在线作业3【标准答案】

(单选题)1: （    ）是以物质燃烧所产生的火焰热辐射为检测对象的火灾探测方法。

A: 热(温度)检测法 B: 光电探测方法 C: 空气离化火灾探测方法 D: 光辐射或火焰辐射探测方法正确答案:(单选题)2:    增安型防爆仪表指的是（    ）。

A: 隔爆型 B: 防爆通风充气型 C: 防爆充油型 D: 防爆安全型正确答案:(单选题)3:     以下检测方法中对人体有害，需要做特殊防护的是（    ）。

A: 超声检测 B: 射线检测 C: 磁粉检测 D: 红外检测正确答案:(单选题)4: 阻燃属于（    ）技术。

A: 灾前抑制 B: 前兆检测 C: 早期监测 D: 灾害扑救正确答案:(单选题)5:  物位检测仪表，一般要求正常液位为最大刻度的（   ）左右。

A: 40%  B: 50%  C: 60%  D: 70%正确答案:(多选题)6: 以下能对霍尔电势产生影响的有（    ）。

A: 霍尔元件的灵敏度B: 激励电流C: 磁感应强度D: 磁场方向和霍尔元件的夹角正确答案:(多选题)7: 以下属于反馈网络的有（    ）。

测试技术基础

东北大学继续教育学院测试技术基础试卷（作业考核线上2） A 卷（共 5 页）一、1. 调幅波可以看作是载波与调制波的乘积。

（√）2. 若x(t) 的傅里叶变换是X（f），则x(0.1t)的傅里叶变换是5X(5f)。

（×）3. 在进行振动测量时，压电式传感器联接电荷放大器时，电缆长度会影响仪器的输出。

（）4. 双螺线管差动型传感器比单螺线管型电感式传感器有较高的灵敏度和线性。

（√）5. 扭矩测量时，测量传感器应变片应贴在与轴线成90度的方向上。

（×）6. 当金属板置于变化着的磁场中时，或者在磁场中运动时，在金属板上产生感应电流，这种电流在金属体内是闭合的，所以称为涡流。

（√）7. 某些物质，当沿着一定方向对其加力而使其变形时，在一定表面上将产生电荷，当外力去掉后，又重新回到不带电状态，这种现象称为压电效应。

（√）8. 若随机信号x(t)和y(t)的均值都为0，当τ→∞时，则Rxy(τ)= 0。

（√）9. 任何样本的时间平均等于总体平均的随机信号被称为各态历经信号。

（√）10. 用一阶系统作测量装置，为了获得较佳的工作性能，其时间常数τ应尽量小。

（√）11. 传感器的灵敏度越高，就意味传感器所感知的变化量越大。

（×）12. 采样时为了不产生频谱混叠，采样频率必须大于信号最高频率的3倍。

（×）二、单项选择题（每题2分，共计24分）1、概率密度函数曲线下的面积是（C）。

A.0.1B.0.5C.1.0D.2.02 一般周期信号可以利用傅里叶级数展开成（B）不同频率的谐波信号的线性叠加。

A.两个B.多个乃至无穷多个C.偶数个D.奇数个：3用二阶系统作测量装置时,为获得较宽的工作频率范围,则系统的阻尼比应( D)。

A.愈大愈好B.愈小愈好C.接近1/2D.接近4. 不能用确定的数学公式表示的信号是（C）信号。

A.复杂周期信号：B.非周期：C.随机：D.瞬态：5 非线性度是表示定度(标定)曲线（A）的程度。

2020年最新奥鹏东北大学20春学期《测试技术基础》在线平时作业3-参考答案

AA
BB
CC
DD
正确答案：B
4
选择题:
由两个时间具有少量频率差的波形引起的拍频等于（）
（A）两个频率的平均
（B）两个频率的和
（c）两个频率的差
（D）两个频率之比
AA
BB
CC
DD
正确答案：C
5
记录磁带慢录快放，放演信号的频谱带宽（）
A变窄，幅值压低
B扩展，幅值压低
C变窄，幅值增高
D扩展，幅值增高
我的答案：B
A错误
B正确
正确答案：B
4
判断题实心圆柱弹性元件高度H变小时，弹性元件固有频率降低。
A错误
B正确
正确答案：A
5
引用误差是仪表的最大示值误差与仪表的满量程之比。（）
A错误
B正确
正确答案：B
6
椭圆齿轮流量计是借助于固定的容积来计量流量的，与流体的流动状态及粘度有关。（）
A错误
B正确
正确答案：A
7
稳态正弦激振是最普遍的激振方法，它是借助激振设备对被测对象施加一个频率可控的瞬态激振力。（）
DD
正确答案：C
10
不失真的幅频相频特性
AA
BB
CC
DD
正确答案：C
二、判断题
共10题，5
1
附加传感器质量将使被测振动系统的固有频率降低。（）
A错误
B正确
正确答案：B
2
若信号的独立变量取值离散，则是离散信号。
A错误
B正确
正确答案：B
3
传感器的功能是将被测信息转换成某种电信号的器件。它包括敏感器和转换器两部分。
正确答案：B
6
将若矩形窗函数

东大19春学期《测试技术基础》在线作业1参考答案

我们知道立法活动的论后是立法者对不同利益间的衡量。无效婚姻和可撤销婚姻制度衡量的是公共利益、道德秩序与个人的意思自治，其法律结果应当衡量的是当事人对利益的危害程度和当事人的责任程度以及其应适当承受的不利后果。但是法律结果却被规定在同一个条文里适用同样的结果，这显然是不合无的。如果不区分两者的法律后果，那么二者的法定情形的重构从现实层面上来讲也就毫无意义了。
其次，笔者认为对婚姻无效与被撤销后的财产分割应方式当加以丰富。我国现在的无效婚姻与可撤销婚姻制度的法律后果中对财产的规定非常单一，忽略了当事人在该婚姻因违法导致无效过程中的主观意志和责任程度，采取各打五十大板的做法不利于发挥法律惩恶扬善的功能。笔者认为在婚姻被撤销或被确认无效后的财产分配中应当参虑双方当事人的主观意志和责任程度，以此作出与之相匹配的分割方案。换句话说主要从“是否知道存在婚姻无效和可撤销的法定事由”和“对法定事由是否有过错”这两个维度来参虑财产的划分。
A.A
B.B
C.C
D.D
正确答案:C
4.
选择题
A.A
B.B
C.C
D.D
正确答案:C
5.
选择题
A.A
B.B
C.C
D.D
正确答案:D
6.
傅立叶变换性质
A.A
B.B
C.C
D.D
正确答案:D
7.在随机误差分析中，标准差s决定了随机误差正态分布的形态，
下面对s1、s2和s3间的关系表达正确的是（）
（A）s1<s2<s3 (B) s1>s2>s3
A.错误
B.正确
正确答案:A
6.直接比较型A/D转换器将输入模拟电压信号直接与作为标准的参考电压信号相比较，得到相应的数字编码（）

东北大学19春学期《测试技术基础》在线作业123答案

19春学期《测试技术基础》在线作业1
选择题1.概率密度函数曲线下的面积等于（）A.0.1B.0.7C.1.0D.2.0
A.A
B.B
C.C
D.D
正确答案:C
时域信号与频域信号
A.A
B.B
C.C
D.D
正确答案:C
两个信号叠加:
A.A
B.B
C.C
D.D
正确答案:C
选择题
A.A
B.B
C.C
D.D
正确答案:C
选择题
A.A
B.B
C.C
D.D
正确答案:D
傅立叶变换性质
A.A
B.B
C.C
D.D
正确答案:D
在随机误差分析中，标准差s决定了随机误差正态分布的形态，下面对s1、s2和s3间的关系表达正确的是（）（A）s1s2s3(B)s1s2s3（C）s2s1s3(D)s3s1s2
A.A
B.B
C.C
D.D
正确答案:A
传感器的动态特性越好，说明传感器的响应在被测频率范围内（）。

A.精度越高
B.精度越差
C.对被测信号的反应能力越快
D.对被测信号的反应能力越慢
正确答案:C
下面对线性系统的输入、输出间关系表述正确的是
A.A
B.B
C.C
D.D
正确答案:B
记录磁带慢录快放，放演信号的频谱带宽（）
A.变窄，幅值压低
B.扩展，幅值压低
C.变窄，幅值增高
D.扩展，幅值增高。

测试技术基础习题答案-最新参考

第二章局部题目答案2-21．求正弦信号)2sin()(t TA t x π=的单边、双边频谱、实频图、虚频图，如该信号延时4/T 后，其各频谱如何变化？解： (1)由于22()sin()cos()2x t A t A t T T πππ==-，符合三角函数展开形式，那么在2Tπ处：1n A =，所以，单边频谱图为图1的〔a 〕。

对)2sin()(t T A t x π=进展复指数展开：由于222()sin()()2j t j tT T jA x t A t e e T πππ-==- 所以，在2T π-处：2n jA C =，0nR C =，2nI A C =，||2n A C =，2n πθ=在2T π处：2n jA C =-，0nR C =，2nI A C =-，||2n A C =，2n πθ=-所以，实频图、虚频图、双边幅频图、双边相频图分别如图1的(b)、(c)、(d)、(e)。

2Tπ2Tπ-(a)单边幅频图 (b) 实频图 (c) 虚频图 (d) )双边幅频图 (e) 双边相频图图1 正弦信号x (t)的频谱〔2〕当延迟4/T 后，()x t 变为2()sin ()4T x t A t Tπ⎡⎤=-⎢⎥⎣⎦，由于222()sin ()cos ()cos 442T T x t A t A t A t T T T πππππ⎡⎤⎡⎤⎛⎫=-=--=- ⎪⎢⎥⎢⎥⎣⎦⎣⎦⎝⎭，符合三角函数展开形式，那么在2Tπ处：1n A =，所以，单边频谱图为图2的〔a 〕。

对222()sin ()sin()cos()42T T x t A t A t A t TT T πππ⎡⎤=-=-=-⎢⎥⎣⎦进展复指数展开，由于222()cos()()2j t j tT TA x t A t e e T πππ--=-=+ 所以，在2T π-处：2n A C =-，2nR A C =-，0nI C =，||2n AC =，n θπ=在2T π处：2n A C =-，2nR A C =-，0nI C =，||2n AC =，n θπ= 所以，实频图、虚频图、双边幅频图、双边相频图分别如图2的(b)、(c)、(d)、(e)。