有关混频，以下说法错误的是（ ）。
无线电发射机需要经过上混频，把已调波的载波频率从77 mhz提高到210 mhz，需要的本振信号频率为（ ）。
无线电接收机接收1130 khz的高频已调波，经过下混频，检波前的中频已调波频率是465 khz，本振信号频率为（ ）。
某器件的转移特性如图所示，已调波us = uam = u(1 macoswt)coswct，本振信号ul = ulmcoswlt，ulm >> u。当wi = wl - wc时，混频跨导gc为（ ）。
晶体管放大器混频电路和晶体管的转移特性如图所示，gm为晶体管的交流跨导，已调波us = udsb = ucoswtcoswct，本振信号ul = ulmcoswlt，ulm >> u，中频频率wi = wl - wc，直流偏置电压ubb = ubeq = ube(on)。以下分析中错误的是（ ）。
二极管混频电路如图所示，vd1和vd2为理想二极管，已调波us = uam = u(1 macoswt)coswct，本振信号ul = ulmcoswlt，ulm >> u，中频频率wi = wl - wc，带通滤波器bpf的中心频率w0 = wi，带宽bwbpf > 2w，通带内增益kf = 1，输入电阻已折算入负载电阻rl。以下分析中错误的是（ ）。
以下不属于混频器主要性能指标的是（ ）。
有关无线电接收机下混频时的干扰，以下说法错误的是（ ）。
接收机下混频的中频频率fi = 500 khz，接收频率fs = 1500 khz的已调波时受到干扰，此时没有其它干扰信号，此类干扰为（ ）。
接收机下混频的中频频率fi = 465 khz，接收频率fs = 550 khz的已调波时，也收到了频率fn = 1480 khz的干扰信号，此类干扰为（ ）。
( ) what does the word ‘reprimand’ mean?
( )what does the word ‘bustling’ mean?
( ) what does the word ‘tedious’ mean?
( ) vocabulary plays a very important role in second language listening comprehension.
( ) compared with reading comprehension, it is difficult to make form-meaning connection of a word in listening comprehension. therefore, there is no need to match the spoken form and the meaning of a word.
( ) guessing the meaning of a new word is a useful strategy in listening comprehension.
___________ into the various concepts of time in different cultures,
we could get a general idea about the different ____________ on time and,
more deeply, the different cultures ____________ in it.
realizing the differences, we should ____________ ourselves
to the strategy of ____________ in doing business
with a member from a ____________ culture,
in order to ____________ misunderstandings,
____________ or even culture shock.
( )when mentioning citizen kane, the great dictator, casablanca, what tense does the speaker use?
( )what are the three basic features of hollywood patterned films?
( ) grammar is not important because it does not give meaning.
( ) two sentences with exactly the same words can differ in meaning.
( ) grammar is very important as it helps increase accuracy.
film-making _____________from economy and high technology.
the us ________________ the battle field in the first world war
and its economy _________________during and after the war.
during the decade 1921–1931, sometimes called as the “golden period of silent films,” successful stars, directors, and cameramen ________________hollywood from abroad, infusing hollywood with new talents and different insights.
movies __________________new heights in expression. innovations in technique, content and structural forms were being introduced in films from germany, france, and russia.
( ) which of the following sentences is the one you hear?
( ) which sentence is marked with the intonation you hear?
( ) in the following sentences, words in bold type indicate that they are stressed. which sentence is the one you hear?
( ) the listening process involves the perception of sounds, the recognition of words and the construction of meaning.
( ) some words have similar pronunciations, with only one different phoneme.
( ) in listening, there are reliable cues marking every word boundary clear.
1. joshua jordan earned a ______________degree in physical therapy.
he hopes to open his own practice someday, and says having the expensive ______________ degree is good for his patients,
but hard on his ______________.
2. universities say they’re caught between ___________________,
__________________who have the skills to find work elsewhere if they are not well paid, and falling financial support from state governments.
3. “there _______________________no way
i___________________ created a career for myself that i wanted to do without the use of student loans.”
( ) what does the professor recommend to do first when we begin to formulate a story?
( ) what’s purpose when the professor talks about “say you have three friends… and let’s say…”
( )what does the professor mainly discuss in the lecture?
( ) discourse competence refers to the ability to handle the language beyond the vocabulary level.
( ) the understanding of a sentence or a paragraph might be based on the understanding of the preceding sentence or paragraph.
( ) the word cohesive means being connected or related in a reasonable way to form a whole.
alright everybody, _________________,
well, ___________________how to start creating the characters for the stories you’re writing.
one way of doing that is to come up with what’s called “a character sketch”, ____________ a sketch like a drawing. i guess that’s obvious. it’s um...it’s a...a sketch is a way of getting started on defining your characters’ personalities.
__________, how do we create fictional characters? we don’t just pull them from thin air, do we?
___________we don’t create them out of nothing. we base them, consciously or unconsciously, we base them on real people, or we blend several people’s traits, their attributes into one character.
_______when people think fiction, they may assume the characters come from the author’s imagination.
( )what is the conversation mainly about？
( )what can you predict when you hear the professor asking about the student’s observing a class for his approaches to education paper?
( )what information in context can not help you understand the word “interdisciplinary” ?
( ) planning what to focus on before listening is a cognitive strategy.
metacognitive strategies include note-taking, monitoring and assessing during listening.
( ) listening together, sharing understanding, solving problems together and exchanging ideas belong to social and affective strategies.
in order to improve your listening skills, you can use certain ________ to support the listening process.
before you listen, think about the ________ of the text you will hear.
what do you already know about it? what could possibly be the content of the text? which words would ____________?
while you are listening, it is not necessary to understand every single word. try to ________ those words that you think are less important.
also, if there are words or issues that you don't understand, use your general knowledge or the ________ to find out the meaning.
you need to focus on ____________ and facts as well.
to remember the information, you’d better ____________ to help you memorize important points. pay attention to the intonation and stress of the speaker so that you can understand what you hear better.
last but not least, try to think ________.
( ) what is the purpose of this audio clip?
( ) what is the target audience?
( ) what is the main content of this audio clip?
( ) the main purpose of a tv program on learning english pronunciation is to persuade.
( ) knowing the purpose of the speaker or the listening material can help us judge what we hear.
( ) it is not necessary to confirm the information source which the speaker uses.
well, for those of you who went out today, i don't have to tell you it was________,
but muggy for most of the state, with the _________temperatures in the low to mid 90s.
the city of elkview had the high for the day of ________ degrees. and that's hot. i'm glad i'm working indoors today!
for those of you planning ________activities tomorrow, you can expect fair skies for most of saturday with temperatures in the high 90's.
however, things might change by saturday evening with a ________front moving in.
we can expect light scattered ________over the northern part of the state bringing slightly cooler temperatures in the eighties, but this rain should taper off by mid sunday morning. it will be partly cloudy for most of the morning, but these clouds should move out by mid-afternoon.
skies should be clear ________________
for those wanting to catch a glimpse of the partial lunar________. it should start at 10:47 pm. and that's all for today's weather.
( ) what issue is the speaker mainly discussing?
( ) what is not a problem mentioned by the speaker?
( ) a question refers to a matter or situation that is difficult to handle.
( ) we can evaluate a problem by judging from its accuracy, relevance and significance.
( ) questions, problems and issues are things that require solutions or discussions.
__________ is a natural process.
many species had ceased to exist before humans __________.
however, in the last 400 years, the number of animals and plants becoming __________has reached crisis point.
human population levels have risen dramatically in the same time period and man’s predatory __________
combined with his ruthless consumption of natural __________are directly responsible for the situation.
( ) which of the following options is the speaker’s statement?
( ) which of the following options is not the speaker’s opinion?
( ) if we judge someone’s opinion, whether he or she has sufficient information to back his or her claims or ideas should be paid attention to.
( ) the dodo birds went extinct a few centuries ago. this is a statement.
( ) opinions are things that are known to have occurred, to exist or to be true.
as internet usage continues to rise throughout the world, the ________of cybercrime also grows.
while some of these crimes are relatively ________and commonplace,
others are very________.
here are a few of the more common forms of cybercrime. the most common type of cybercrime is sending ________messages. hundreds of copies of the same message flood the internet in an attempt to force the message on people who would not otherwise choose to receive it. credit fraud is another common form of cybercrime.
certain computer viruses can ________keystrokes
on your ________and send them to hackers, who can then take your social security number, credit card number and home address.
harasent, or cyber bullying, is a growing problem among ________.
examples of cyber bullying include sending unkind text messages or emails, spreading ________ by email (or posting malicious gossip on social networking sites) and also posting embarrassing pictures, videos, websites, or fake profiles.
( ) according to the speaker, what is the point of understanding the concept of domestic violence?
( ) which of the following actions can be defined as psychological abuse?
( ) what does the speaker imply at the end of the speech?
( ) a concept is a generalized idea expressed in symbols or in words. it is about a class of objects, attributes, occurrences, or processes.
( ) when we say dogs are friends of humans, we usually think of them as a mental abstraction.
( ) all concepts have the same level of abstraction.
while china has become increasingly influenced by western culture, the traditional family structure is still highly valued and holds a __________ position in chinese culture.
but, with the rapid development china has experienced over the last few decades, it appears that both the country’s __________________and family structure are changing.
divorce rates in china have been _____________for ten consecutive years.
last year alone saw a shocking _____________orces.
this seems to have become _____________in line with developed countries in western europe and north america.
these changes in the chinese society have also led to young people, especially those born after 1980, to feel less ____________to traditional marriage than their parents. if they are not happy in a relationship, they simply decide to get a orce.
( ) what is the assumption behind “in thinking about it, i found myself intrigued by some lessons from an unlikely source: singapore.”？
( ) what do the living conditions of the muslim population in britain prove?
( ) what is the assumption behind “we were a nation that was not meant to be.”?
( ) an assumption is something that we accept as true or as certain to happen, without question or proof.
( ) critical thinkers need to make assumptions that are questionable.
( ) assumptions are always true.
race and ethnicity are important concepts in both ________ and everyday life.
when one says that he is an american, a chinese, or a nigerian, he identifies himself with a certain kind of________. but is that a race or an ethnicity that he identifies with?
there are actually different definitions for race and ethnicity and social scientists argue against each other for their definitions of the two terms. the traditional definition of race and ethnicity is related to ________
and ________ factors respectively.
race refers to a person’s ________ characteristics, such as bone structure and skin, hair, or eye color.
ethnicity, however, refers to ________ factors, including nationality, regional culture, ancestry and language.
an example of race is brown, white, or black skin, while an example of ethnicity is german or spanish ancestry (regardless of race). one’s race is determined by ____________
while one’s ethnicity is determined based on the social and cultural groups one ___________.
( ) what can we infer from “the native americans didn’t think they were being discovered?”
( ) what can we infer from that the former prime minister of the bahamas “didn’t care which island that it was as long as it was still in the bahamas?”
( ) according to william fowler, how should we treat columbus?
( ) in listening, inferences refer to a piece of information that is known to be true.
( ) as a critical listener, we should be able to check whether the inferences made are consistent with each other.
( ) inferences are always based on information.
new york and chicago will mark this day with__________
and celebrations of christopher columbus’ voyage and his italian__________,
and some will __________the day
calling for a __________of the impact that
that voyage had on __________american communities.
so, why the __________stories? well, we wanted to take this opportunity to brush up on some of the facts about christopher columbus that we may never have learned or have forgotten from school.
( ) what are the possible consequences of obesity based on the information of this video?
( ) what can you infer from nancy snyderman’s argument about america’s obesity epidemic?
( ) implications and consequences are possible results of an action, event and decision that follow our questioning.
( ) a skilled critical listener knows how to search for negative as well as positive implications and infer more than what is actually implied.
( ) there is no difference between what a statement or situation actually implies and what we infer from them.
anyone who has tried to lose weight through ________ knows how difficult it is,
and scientists have yet to develop a magic ________ that keeps the kilos off permanently.
now researchers are beginning to understand why ________ weight loss is so hard. they believe it has to do with damage to the part of the brain that’s involved in weight control.
if ________ people would just stop overeating, switch to a healthful diet and start exercising, they would lose weight. but if they do, they may quickly gain it back again.
the reason, say researchers, is not a lack of ________ but injury to brain cells, or neurons, in the hypothalamus,
a structure deep in the brain that helps control a number of body functions including ________ and weight.
( ) what is the speaker’s point of view when talking about the internet’s influence?
( ) there is a scene depicting a busy and chaotic online life at the beginning of the video. what’s the purpose of this scene?
( ) a point of view refers to the process of our thinking.
( ) our ideas are shaped by our points of view.
( ) we human beings can view a person or an event from every single vantage point at the same time.
we spend so much time on ________ like facebook, twitter, and youtube.
and with the rise of ________ computing, we are literally connecting almost 24 hours a day, 7 days a week.
advanced technology and ________ design has made it way too easy
to share things with our friends and________,
making it the perfect environment for almost a domino-effect to occur on all levels of ____________
with the perfect piece of shareable________.
推销的特点有很多，以下哪些属于推销的特点。
推销员是推销活动中的推销客体，是现代推销学的研究对象之一。
推销是双赢的策略，就是对每一分钱来说，要各赚一半才行。
寻找潜在顾客是推销的基本职能之一
推销品是推销活动中的推销对象，是现代推销学的研究对象之一。
“引子”成为准顾客必须具备的基本条件是
成功的推销需要推销人员主动寻找顾客、向顾客介绍产品的特色、优点和利益，需要推销人员强力推销，说服顾客购买，而不必考虑顾客的感受。
中心开花法寻找准顾客的关键是找出核心人物，取得他们的信任和支持，让他们去带动大批的潜在买主。
推销员有着较强的成就感，关注自己的推销业绩，以完成或超额完成销售任务作为推销工作的首选目标，忽视或完全不关心顾客的需要与心理。这是推销方格理论中的推销技术导向型。
向经销商推销也应强调推销产品的使用价值观念。
标准站姿要求不包括
穿着套裙的四大禁忌不包括
握手时
送名片的方式是
入座时应做椅子的
新分离技术的发展，一般包括哪些选项?
以下分离过程中，哪些使用了质量分离剂？
生产大装置中的化学、物理过程和实验室玻璃器皿中的过程，主要区别在于：
分离设备的选择，应该考虑哪些问题?
分离单元操作的概念，最早是g.e.戴维斯的《化学工程手册》确立的。
以下表示计算机辅助加工的是（ ）
当进入cam加工环境操作时，可以单击“开始”→“加工”按钮，也可以按以下组合键（ ）
在进入ug加工环境配置中，以下为通用加工配置的是（ ）
在nx8.5加工环境中需要设置工件坐标系，则需要在以下（ ）中进行设置。
在nx8.5加工环境中，设置、查看刀具信息的视图为（ ）
cam仿真加工中可以不用设置工件坐标系
cam铣削加工时，工件坐标系的位置通常设置在工件上表面的中心置处。
mcs表示机床坐标系，wcs表示工作坐标系。
在mcs_mill中进行安全设置选项，通常选择工件上表面并且设置一定的安全距离。
在workpiece选项设置中，首先应该将加工的零件设置为毛坯。
以下表示面铣削的是（ ）。
在运用边界面铣削（face_milling）时，当边界的内部一个孔，现要将该边界面铣平，则在“忽略孔”前端选项中应该
在切削模式选项中，“沿所有指定部件几何体的同心偏置切削”描述的是
在切削模式选项中，以下走刀方式始终沿着一个方向进刀的是
在步距设置中，通常是以刀具直径的百分比（%）进行设置的，以下设置的参数合理的是
边界平面铣削（face-milling），一般用于加工零件的表面几何部位，适用于半精加工和精加工。
“指定部件”就是指定表示成品的体，为使用过切检查，必须指定或继承实体部件几何体。
在切削模式选项中，跟随周边指的是沿部件或毛坯几何体定义的最外侧边缘偏置进行切削。
顺铣就是铣刀旋转方向与工件进给方向相反，逆铣就是铣刀旋转方向与工件进给方向相同。
刀具在区域内或区域间转移时，一般默认为“安全距离-刀轴”，也就是说刀具在工件坐标系的原点转移。
以下表示平面铣削工序子类型的是
在运用平面铣削时，需要不选择部件边界中孔边界，则在“忽略孔”复选框中应该
平面铣削中的底部面表示
平面铣削方法中边界的 “材料侧”表示
检查几何体指的是
平面铣削的边界只能是平面轮廓。
当平面铣削的切削层中选择“固定深度”时，深度分层是均匀的。
在切削模式选项中，跟随周边和跟随部件的道路是完全一样的。
顺铣就是铣刀旋转方向与工件进给方向相同，逆铣就是铣刀旋转方向与工件进给方向相反。
刀具在下刀时，速度有g00变为g01的位置是由进刀参数的“高度”值决定的。
光电效应是由哪位科学家最早发现的（ ）
无线电波，可见光和伽马射线的共同点是（ ）
根据基尔霍夫定律，物体对某一波长的吸收率越大，则物体在该波长上的辐射度（ ）
光子可以用下列哪些物理量进行描述（ ）
下面对红外线描述正确的是（ ）
辐射强度用于描述点源，辐亮度用于描述面源。
热平衡时黑体辐射的能量密度由黑体的温度决定。
海面的红外辐射主要集中在1~3微米和8~12微米。
辐射源可以分为三类，即黑体，灰体和（ ）
热平衡条件下，温度越高时黑体辐射的单色能量密度峰值对应的光波长越（ ）。
大气对光的衰减主要由（ ）和吸收两部分组成。
以下不属于调制盘功能的是
以下不属于调幅式调制盘的是
下面那个不属于“十字”形探测器的优点
以下不属于红外成像制导特点的是
下面那些导弹采用了红外点源制导方式
光学调制盘的作用有哪些
光机扫描成像系统按扫描方向和元件排列可分为哪三种方式（ ）
对于大面积背景辐射，在整个周期内保持调制盘的透过系数为恒定值是空间滤波的重要原则
制冷型探测器主要用于探测低温目标，制冷能够有效减小器件噪声。
智慧型红外诱饵能够实现对目标的辐射谱段和运动特性等特征的模拟。
旭日式调制盘的下半部分是非条幅状图案，其透过率保持在
在相同视场约束下，l形探测器的臂长是十字形探测器的
红外烟雾分为吸收型烟雾和 型烟雾
下述关于玻尔兹曼分布的说法，哪个是不正确的？
关于受激辐射跃迁，不正确的说法是（ ）
一束激光，通过长度为3mm的某质后，功率衰减为原来的一半，假设光衰减全部是由吸收引起的，则介质对入射光的吸收系数为多少？
关于自激振荡，不正确的说法是（ ）
以下属于激光主动制导优点的是
属于激光驾束编码方法的是
下列说法，正确的是( )
关于增益的说法，正确的是（ ）
关于光学谐振腔的作用，正确的说法是（ ）
激光是介于可见光和紫外线之间的一种光波
激光相干探测可以同时实现测距、测速和测量发射光强度的功能。
实现粒子数（集居数）反转，不一定就能实现激光振荡。
处于热平衡状态的原子系统里，单位时间内发生受激辐射的原子数目与受激吸收的原子数目一样多。
角的大小是衡量光束方向性好坏的标志
激光距离成像多采用 探测方式
激光器一般由谐振腔、 和泵浦源三个部分组成。
光学正反馈条件是指光波在腔内任意位置出发，在腔内往返一周产生的相位是2π的整数倍，光学正反馈条件也可以表示为腔长等于 的整数倍。
设he-ne激光器腔长l为0.3m，气体折射率n≈1，则出射激光的基模频率为（ ）
以下不属于图像对比度跟踪范围的是（ ）
下面说法不正确的是（ ）
下列能够产生短脉冲激光的激光技术有（ ）
电视成像制导多采用人在回路方式或者人工锁定目标的方式。
电视成像导引头的锁定方式可以分为“发射前锁定”和 。
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