Toefl Junior词汇备考指引

Toefl Junior词汇备考指引
Toefl Junior词汇备考指引

【Toefl Junior词汇备考指引】

Toefl Junior,即初中托福,俗称为小托福。是ETS(美国教育考试服务中心)专为全球11—15岁中小学生开发的权威英语能力测试。该考试不仅可以作为中小学生北美高中留学的英语能力认证,更可以测评现阶段学生的英语水平,为提高英语能力或者将来参加托福考试提供权威指导。TOEFL Junior初中托福考试主要由三大部分组成:听力、语言形式和含义(可以理解为语法和词汇)、阅读。考试时间大概2个小时,满分为900分。对于这项新兴的考试,许多考生感到比较陌生,备考方法不知从何下手,下面将从词汇方面做简单指导。

一、到底该背哪些单词?

对于英语考试而言(包括Toefl Junior),要想读懂、听懂文章,其中最重要的单词是中学阶段所学的单词,其中初中2000左右,高中约3500。千万不要以为自己参加的是高大上的小托福考试而不背中学的词汇,中学词汇同样出现在TOEFL JUNIOR的文章中。小托福所要求的词汇量在3000左右,这3000的词汇大部分是初中加高中所学的单词,还有一部分是在大学四级当中会出现的单词,比如一些较学术性的词汇,如生物学、地质学、天文学等。三者之间关犹如齿轮,环环相扣,少一环运转起来都很困难,如下图所示:

小托福所要求的词汇量在3000左右

我们以Toefl Junior官网的样题中的一篇阅读理解为例看下其中的单词难度:

小托福词汇难度

该篇文章整体难度较简单,整篇文章不到100个词,其中绝大多数是初高中词汇,而在四级词汇表中出现的单词有gymnasium,feature,variety,professional,performer,permission,guardian共7个,约占7%。可以看出,真正帮助考生理解文章内容的单词是这93%的中学词汇,这就说明了中学词汇对于Toefl Junior的重要性。对于小托福的考生而言,可能这93%中大部分单词都不认识,或者见过但不知道意思,所以词汇学习内容是先以中学词汇为主,打好基础后再学习其余分类学科单词。

二、那么该怎么学习Toefl Junior单词?

针对小托福考生年纪小、脑子灵活、记东西快等特点,在学习Toefl Junior单词时可采取以下两个方法:拼读+联想2.词根词缀。

1.拼读+联想。记单词首先看到的是形,即拼写,而通过语音知识的学习和一定单词量的积累,拼写和语音之间是可以构筑桥梁的。这样在见到生词的时候,虽然没有音标,也可以通过这个词的拼写读出发音;反之,对于熟词,可以通过常用字母组合的发音,根据发音把单词拼写出来,对于听力中的关键词这是一个非常重要的技巧。对于年龄较小同学而言,拼读法是比较直接而又简单的记单词的方法。

但是拼读法也有其局限性,大量纯语音单位和字母的堆积会导致学生感觉枯燥乏味,而且单纯依靠拼读法所能记住的单词还是有限,因此在其中适当加入联想记忆的方法,使单词记忆更加形象生动。而能通过语音拼读所记的单词同时又是后面词根词缀记忆方法中会用到的单词,所以是就方法而言,同样也是环环相扣,缺一不可。比如act,在语音部分学习actor,action,activity,active,fact等单词后,在词根词缀法时就会用到其中的单词如fact去记忆factor,manufacture,manufacturer,perfect,fiction等同源单词。

2.词根词缀法。和汉字一样,英语单词同样也有“偏旁”“部首”,即英语构词中的词根词缀。对于英语初学者,词根词缀的概念可能很陌生,因为接触的单词少,所以很少能发现单词与单词的联系。等单词积累到一定量之后,就会发现许多单词在构词时都是有重复的部分,比如product, produce,progress,这三个词用的都是同一个前缀pro;progress,aggression,ingress等词都含有词根gres;aggression,nation,foundation等词都含有词根-tion。英语中的前缀、后缀、词根都有各自的作用,通过前期单词的积累,基本已

经接触到常见的词根词缀了,再加以系统的梳理,这样就可以通过词根词缀去记忆更多的单词了。词根词缀除了可以帮助记忆单词之外,还可以猜词意、词性,这也是在托福、托福junior 等考试中常考到的(阅读题中的词汇题)。所以词根词缀对于学生来说还是很重要的单词记忆方法。

数字信号处理试题

一、 单 项选择题 1. 序列x(n)=Re(e jn π/12 )+I m (e jn π/18 ),周期为( )。 A. 18π B. 72 C. 18π D. 36 2. 设C 为Z 变换X(z)收敛域内的一条包围原点的闭曲线,F(z)=X(z)z n-1 ,用留数法求X(z)的反变换时( )。 A. 只能用F(z)在C 内的全部极点 B. 只能用F(z)在C 外的全部极点 C. 必须用收敛域内的全部极点 D. 用F(z)在C 内的全部极点或C 外的全部极点 3. 有限长序列h(n)(0≤n ≤N-1)关于τ= 2 1 -N 偶对称的条件是( )。 A. h(n)=h(N-n) B. h(n)=h(N-n-1) C. h(n)=h(-n) D. h(n)=h(N+n-1) 4. 对于x(n)= n )21(u(n)的Z 变换,( )。 A. 零点为z=21,极点为z=0 B. 零点为z=0,极点为z=21 C. 零点为z=21,极点为z=1 D. 零点为z=2 1 ,极点为z=2 5、)()(101n R n x =,)()(72n R n x =,用DFT 计算二者的线性卷积,为使计算量尽可能的少,应使DFT 的长度N 满足 。 A.16>N B.16=N C.160,Z 变换的收敛域为( )。 A. 0<|z|<∞ B. |z|>0 C. |z|<∞ D. |z|≤∞ 9.在对连续信号均匀采样时,要从离散采样值不失真恢复原信号,则采样角频率Ωs 与信号最高截止频率Ωc 应满足关系( ) A. Ωs>2Ωc B. Ωs>Ωc C. Ωs<Ωc D. |Ωs<2Ωc 10.下列系统(其中y(n)为输出序列,x(n)为输入序列)中哪个属于线性系统?( ) A.y(n)=y(n-1)x(n) B.y(n)=x(n)/x(n+1) C.y(n)=x(n)+1 D.y(n)=x(n)-x(n-1)

TOEFL-Junior语言形式与含义-语法点分类练习

TJ时态题 1. He ___ one of his other classes on a field trip to the aquarium this Saturday. A. take B. to take C. is taking D. was taken TJ语态题 1. A man’s wristwatch ___ in the lobby of Liugi’s Pizza Restaurant on Tuesday, February 16. A. finds B. finding C. has found D. was found 2. Given new technologies and advanced training techniques, ski jumping records will surely continue ___ A. are broken B. to be broken C. breaking them D. have been breaking 3. They ___ to provide a lot of living spaces, not for long, dangerous voyages. A. build B. are built C. have built D. are building TJ连词/介词/副词 1. _____ you were at basketball practice today, your teacher, Mr. Morris, called on the phone to talk with you. A.So B. While C. Because D. Although 2. _____ the construction , the front entrance to the science building will be closed. ____, all students will have to use the doors on the north side to enter the building. A. At B. On C. Over D. During A. As a result B. Even though C. All of a sudden D. On the other hand 3. Cuckoos, cowbirds, and widowbirds are three examples ___ birds that are brood parasites. A. of B. by C. for D. from 4. My mother asked me if I wanted anyone else to come, __ the first person I thought of was you! A. but B. and C. while D. therefore 5. Known throughout recorded history, they are __- used by people all around the world. A. yet B. still C. ever D. then 6. ____ the way they are made may be different from region to region, houseboats are very similar in many ways. A.It is B.When C. Because D. Although 7. Most of them have flat bottoms, and they are wider ___ normal boats. A. of B. as C. than D. from TJ词汇 1.He said he is___ you the chance first because of the great report you wrote about whale. A. asking B. offering C. deciding D. discussing 2. While this work is being done, most classes will continue as usual inside the building. However, if some classes need to be moved _____ to other rooms, teachers

学术写作中常用高级用词替换

常用词的学术替换 动词替换: 1.Improve 提高: Promote: 促进AC之间的贸易promote the trade between A and C; He was promoted to senior manager in this company. Advance: our understanding of human genetics has considerably(非常的,可换做vastly) advanced. Enhance: the publi city has enhanced his reputation.这次宣传提高了他的名望 2.change 改变: Transform:多指改头换面,完全改变,不能用于形容slight change。说到人口变化:the increasing population has transformed the landscape and structure of local industry structure.人口剧增改变了小镇的景色以及当地的工业结构 3.Emphasize 强调: Highlight:the report highlight the decline in the numbers of native(可以换作local) plants and insects. Stress: He stresses the need for parents to listen to their children. Accentuate: the crisis accentuates the gap between rich and poor. (highlight and emphasize 的区别:highlight是告诉人们重点,因而能够让别人注意,类似于老师勾重点;而emphasize则是使重点清晰,不管别人是否能注意得到。而stress则和emphasize差不多) 4.Develop培养: Cultivate: cultivate the ability of … ;培养情操;cultivate a more relaxed and positive way towards life. Nurture: 养育,同样可以指培养人才(talents)the sea nutures ample marine animals. 5.Break 破坏: Impair:impair ability; 主要是破坏能力,莫乱用。 Undermine这个词也是指的是抽象意义上的破坏,有逐渐削弱之意,重点是循序渐进的过程。Undermine one’s ability/confidence/authority/position/credibility Jeopardize: 不能乱用,破坏的东西要上一定的等级才能配上此词。比如Jeopardize the process of peace.破坏和平进程 Devastate特指毁灭、蹂躏the earthquake devastated the whole city. 6.Keep 保存 Preserve、Conserve 保护资源用的就是这个词,不要用protect,protect这个词用在保护具体的东西。 7.deal With解决 Tackle: tackle the problem. Resolve: resolve dispute争论/conflict冲突/problem/issue/crisis危机;来自拉丁语,比较正式。 8.need 需要 Require:xxx requires courage and confidence. Necessitate: 用法不简单,没有摸透。 call for(这也是个很高级的用法,奥巴马就用这个【我不晓得奥巴马咋个用的,原帖是这样

数字信号处理期末试卷!

数字信号处理模拟试题一 一、单项选择题(本大题共10小题,每小题2分,共20分) 在每小题列出的四个备选项中只有一个是符合题目要求的,请将其代码填写在题后的括号内。错选、多选或未选均无分。 1.在对连续信号均匀采样时,要从离散采样值不失真恢复原信号,则采样角频率Ωs与信号最高截止频率Ωc应满足关系(A ) A.Ωs>2Ωc B.Ωs>Ωc C.Ωs<Ωc D.Ωs<2Ωc 2.下列系统(其中y(n)为输出序列,x(n)为输入序列)中哪个属于线性系统?(D) A.y(n)=y(n-1)x(n) B.y(n)=x(n)/x(n+1) C.y(n)=x(n)+1 D.y(n)=x(n)-x(n-1) 3.已知某序列Z变换的收敛域为5>|z|>3,则该序列为(D ) A.有限长序列 B.右边序列 C.左边序列 D.双边序列 4.实偶序列傅里叶变换是(A ) A.实偶序列 B.实奇序列 C.虚偶序列 D.虚奇序列 5.已知x(n)=δ(n),其N点的DFT[x(n)]=X(k),则X(N-1)=(B) A.N-1 B.1 C.0 D.-N+1 6.设两有限长序列的长度分别是M与N,欲通过计算两者的圆周卷积来得到两者的线性卷积,则圆周卷积的点数至少应取(B ) A.M+N B.M+N-1 C.M+N+1 D.2(M+N) 7.下面说法中正确的是(C) A.连续非周期信号的频谱为周期连续函数 B.连续周期信号的频谱为周期连续函数 C.离散非周期信号的频谱为周期连续函数 D.离散周期信号的频谱为周期连续函数 8.下列各种滤波器的结构中哪种不是IIR滤波器的基本结构?(C ) A.直接型 B.级联型 C.频率抽样型 D.并联型 9.下列关于FIR滤波器的说法中正确的是(C) A.FIR滤波器容易设计成线性相位特性

2020高考英语作文热点话题(含必备词汇和范文)--新四大发明!

2020高考英语作文热点话题(含必备词汇和范文)--新四大发明! 中国传统文化出题方向:1. 传统文化与现代文明的关系2. 民俗、民风、民族特色 3. 文化担当与自信 4. 文化传承与传播必备词汇:1. Lantern Festival 元宵节2. Embroidery 刺绣3. Double-Ninth Festival 重阳节4. Tomb Sweeping Day 清明节5. paper cutting 剪纸 6. Siheyuan/Quadrangle 四合院7. Warring States 战国8. Kunqu Opera 昆曲9. Flower Drum Song 花鼓戏10. Confucian culture 儒家文化11. Chinese knotting 中国结12. hot pot 火锅13. South Regions of the Yangtze River 江南14. Tang Poetry 唐诗15. Tang Dynasty 唐朝16. Mid-Autumn Festival 中秋节17. lunar calendar 农历18. the Palace Museum 故宫博物院19. traditional Chinese festivals 中国传统节日20. protecting traditional Chinese culture 保护中国传统文化21. the four great inventions of ancient China 中国古代四大发明22. The Book of Songs/Classic of Poetry 《诗经》23. Records of the Grand Historian 《史记》24.The Story of the Stone 《红楼梦》25. Journey to the West 《西游记》 范文 Protecting Traditional

TOEFL Junior语法题小托福语言形式与含义

TJ时态题 官方指南 1. He ___ one of his other classes on a field trip to the aquarium this Saturday. A. take B. to take C. is taking D. was taken TJ语态题 1. A man’s wristwatch ___ in the lobby of Liugi’s Pizza Restaurant on Tuesday, February 16.A. findsB. findingC. has foundD. was found 2.Givennewtechnologiesandadvancedtrainingtechniques,skijumpingrecordswills urelycontinue ___ A. are broken B. to be broken C. breaking them D. have been breaking 3. They ___ to provide a lot of living spaces, not for long, dangerous voyages. A. build B. are built C. have built D. are building TJ连词/介词/副词 1. _____ you were at basketball practice today, your teacher, Mr. Morris, called on the phone totalk with you. A.So B. While C. Because D. Although 2._____theconstruction,thefrontentrancetothesciencebuildingwillbeclosed.____ ,allstudents will have to use the doors on the north side to enter the building. A. At B. On C. Over D. During A. As a result B. Even though C. All of a sudden D. On the other hand 3. Cuckoos, cowbirds, and widowbirds are three examples ___ birds that are brood parasites.A. ofB. byC. forD. from

四六级写作常用词语高级替换词(四)(副词)

有道学堂四六级干货之写作常用词语高级替换(副词) 非常(very['ver?]) exceedingly[?k'si?d??l?] 【例句】The child has skipped to the third grade as he did exceedingly well in his studies. 【翻译】这孩子因成绩优异而越级升入三年级。 extremely[?k'stri?ml?] 【例句】He had been extremely tactful in dealing with the financial question. 【翻译】他在处理这个财务问题时很有分寸。 considerably [k?n's?d(?)r?bl?] 【例句】The need for sleep varies considerably from person to person. 【翻译】不同的人对睡眠的需要差异相当大。 尤其 (especially [?'spe?(?)l?]) specially ['spe??l?] 【例句】It will be hard to work today---specially when it’s so warm and sunny outside. 【翻译】今天无心工作——尤其是外面这样风和日丽。 notably ['n??t?bl?] 【例句】Some subjects are very popular among students, notably computer science. 【翻译】一些课程在学生当中是非常受欢迎的,尤其是计算机课。 particularly [p?'t?kj?l?l?] 【例句】Traffic is bad, particularly in the city center. 【翻译】交通状况很差,尤其实在市中心。 立即(immediately [?'mi?d??tl?]) directly [d?'rektl?] 【例句】Tell them I’ll be there directly. 【翻译】告诉他们我一会就到。 instantly ['?nst(?)ntl?] 【例句】The diplomat threw in a joke, and the tension was instantly relieved. 【翻译】那位外交官插进一个笑话,紧张的气氛顿时缓和下来。 promptly ['pr?m(p)tl?] 【例句】She promptly seized the opportunity his absence gave her. 【翻译】她立即抓住了因他不在场给她创造的机会。 明显地(clearly ['kl??l?]) obviously ['?bv??sl?] 【例句】Obviously, they've had sponsorship from some big companies. 【翻译】很显然,他们已经得到某些大公司的赞助。 apparently [?'p?r?ntl?] 【例句】Apparently they are getting divorced soon. 【翻译】看样子,他们很快就要离婚。 evidently ['ev?d(?)ntl?] 【例句】Ellis evidently wished to negotiate downwards after Atkinson had set the guidelines.

数字信号处理试题及答案

数字信号处理试题及答案 一、填空题:(每空1分,共18分) 1、 数字频率ω是模拟频率Ω对采样频率s f 的归一化,其值是 连续 (连续还是离散?)。 2、 双边序列z 变换的收敛域形状为 圆环或空集 。 3、 某序列的 DFT 表达式为∑-==1 0)()(N n kn M W n x k X ,由此可以看出,该序列时域的长度为 N ,变换后数字频域上相邻两个频率样点之间的间隔是 M π 2 。 4、 线性时不变系统离散时间因果系统的系统函数为2 52) 1(8)(2 2++--=z z z z z H ,则系统的极点为 2,2 1 21-=-=z z ;系统的稳定性为 不稳定 。系统单位冲激响应)(n h 的初值 4)0(=h ;终值)(∞h 不存在 。 5、 如果序列)(n x 是一长度为64点的有限长序列)630(≤≤n ,序列)(n h 是一长度为128点 的有限长序列)1270(≤≤n ,记)()()(n h n x n y *=(线性卷积),则)(n y 为 64+128-1=191点 点的序列,如果采用基FFT 2算法以快速卷积的方式实现线性卷积,则FFT 的点数至少为 256 点。 6、 用冲激响应不变法将一模拟滤波器映射为数字滤波器时,模拟频率Ω与数字频率ω之间的 映射变换关系为T ω = Ω。用双线性变换法将一模拟滤波器映射为数字滤波器时,模拟频率Ω 与数字频率ω之间的映射变换关系为)2 tan(2ω T =Ω或)2arctan(2T Ω=ω。 7、当线性相位 FIR 数字滤波器满足偶对称条件时,其单位冲激响应)(n h 满足的条件为 )1()(n N h n h --= ,此时对应系统的频率响应)()()(ω?ω ωj j e H e H =,则其对应的相位函数 为ωω?2 1 )(-- =N 。 8、请写出三种常用低通原型模拟滤波器 巴特沃什滤波器 、 切比雪夫滤波器 、 椭圆滤波器 。 二、判断题(每题2分,共10分) 1、 模拟信号也可以与数字信号一样在计算机上进行数字信号处理,只要加一道采样的工序就可 以了。 (╳) 2、 已知某离散时间系统为)35()]([)(+==n x n x T n y ,则该系统为线性时不变系统。(╳)

考研英语:作文主题词汇精选

考研英语:作文主题词汇精选 【摘要】本文给同学们整理汇总一些考研英语中常设计的话题词汇。考研帮携手2016大 纲解析人第一时间解读大纲, ?环保:environmental protection low carbon economy 低碳经济UN climate change conference in Copenhagen哥本哈根联合国气候变化会议Greenhouse effect温室效应Confront the threat of global warming(面临全球变暖的威胁) To reduce the petrol engine exhaust emissions 减少(汽车)的尾气排放 environment- friendly society (生态型社会)contaminate the environment 污染环境? natural resources(自然资源)energy conservation and environmental protection (节能环保)biological balance (生物学平衡)bring about harmony of economic returns and contribution to society and environmental protection (实现经济效益、社会效益和环境效益的统一)curb environmental pollution (治 理环境污染)develop renewable/substitute resources (开发可再生/替代资源) ?经济类:economy boom 蓬勃发展low carbon economy 低碳经济 economic globalization(经济全球化)sustainable development(可持续发展)unfair competition(不正当竞争)promote sales(促销)fake and inferior product(假冒伪劣产品),crack down on fake commodities (打假) purchasing power(购买力)fierce competition(激烈竞争)after-sale service (售后服务)bread –and – butter issue(生计问题)enterprise image(企业形象),brand effect(品牌效应)retail industry (零售行业) wholesale industry (批发行业)credit crisis(信用危机) credit card (信用卡)stabilize the commodity prices(稳定物价)service trade(服务行业)premature consumption超前消费?立志(成功/成才):succeed, achieve success the pursuit of success / achievement / happiness / individual self-realization spare no efforts/pains to do (不遗余力去做某事)= make great effort to do sth, do with full persistence(坚持不懈地做某事), try every means to stay on top (尽一切努力取得 成功)to realize one’s ambiti on(抱负)可以代替“to fulfill one’s dreams” cultivate the sense of individual self-realization 培养一种自我实现(成功)的意识 stand up to/ withstand challenges and difficulties(经得住挑战与困难)?大学生活/ 教育:Education innovative learning(创新学习)higher education(高等教育)drop-out(辍学)fake certificate/diploma(假毕业证/文凭)the craze for graduate school(考研热)diploma craze(文凭热)poverty-stricken students(贫 困学生)further one’s study (深造)quality education(素质教育) teacher-centered,(以教师为中心) student-centered, (以学生为中心)foster

英语六级写作中常用词的替换词

英语六级写作中常用词的替换词 1) 大多数人most people→ the majority of the population 2) 经常often→frequently 3) 我相信I believe→ from my standpoint, from my perspective 4) 必须must→ it is a must for us to… 5) 知道know→ be aware of 6) 因为because→in that 7) 最后at last→eventually 8) 然而but→however 9) 如果if→provided that 10) 各行各业的人all kinds of people→people from all walks of life 11) 引起,导致lead to→contribute to 12) 人people→individuals 13) 好的good→desirable, beneficial 14) 怀的bad→undesirable 15) 很多many→ numerous 16) 越来越more and more→ a(n) increasing/mounting number of 17) 很very→extremely 18) 方面side→aspects 19) 表明show→demonstrate, indicate 20) 利用use→utilize 21) 因此/结果so→therefore 22) 部分part→proportion 23) 提高improve→enhance 24) 改变change→transform 25) 强调/重视emphasize→ attach great importance to 26) 培养develop→cultivate 27) 破坏destroy→undermine 28) 解决deal with →tackle /figure out 29) 普遍的everywhere→universal 30) 明显的obvious→apparent 31) 在当今社会in the modern society→in the current society 32) 使make→enable 5)to begin with, then, furthermore, finally(强烈推荐)6)to start with, next, in addition, finally(强烈推荐)

数字信号处理期末试题及答案汇总

数字信号处理期末试题及答案汇总

数字信号处理卷一 一、填空题(每空1分, 共10分) 1.序列()sin(3/5)x n n π=的周期为 。 2.线性时不变系统的性质有 律、 律、 律。 3.对4 ()()x n R n =的Z 变换为 ,其收敛域为 。 4.抽样序列的Z 变换与离散傅里叶变换DFT 的关系为 。 5.序列x(n)=(1,-2,0,3;n=0,1,2,3), 圆周左移2位得到的序列为 。 6.设LTI 系统输入为x(n) ,系统单位序列响应为h(n),则系统零状态输出y(n)= 。 7.因果序列x(n),在Z →∞时,X(Z)= 。 二、单项选择题(每题2分, 共20分) 1.δ(n)的Z 变换是 ( )A.1 B.δ(ω) C.2πδ(ω) D.2π 2.序列x 1(n )的长度为4,序列x 2(n )的长度为3,则它们线性卷积的长度是 ( ) A. 3 B. 4 C. 6 D. 7 3.LTI 系统,输入x (n )时,输出y (n );输入 为3x (n-2),输出为 ( ) A. y (n-2) B.3y (n-2) C.3y (n ) D.y (n ) 4.下面描述中最适合离散傅立叶变换DFT 的是 ( ) A.时域为离散序列,频域为连续信号 B.时域为离散周期序列,频域也为离散周期序列

C.时域为离散无限长序列,频域为连续周期信号 D.时域为离散有限长序列,频域也为离散有限长序列 5.若一模拟信号为带限,且对其抽样满足奈奎斯特条件,理想条件下将抽样信号通过即可完全不失真恢复原信号()A.理想低通滤波器 B.理想高通滤波器 C.理想带通滤波器 D.理想带阻滤波器 6.下列哪一个系统是因果系统()A.y(n)=x (n+2) B. y(n)= cos(n+1)x (n) C. y(n)=x (2n) D.y(n)=x (- n) 7.一个线性时不变离散系统稳定的充要条件是其系统函数的收敛域包括()A. 实轴 B.原点C.单位圆 D.虚轴 8.已知序列Z变换的收敛域为|z|>2,则该序列为()A.有限长序列 B.无限长序列C.反因果序列 D.因果序列 9.若序列的长度为M,要能够由频域抽样信号X(k)恢复原序列,而不发生时域混叠现象,则频域抽样点数N需满足的条件是( ) A.N≥M B.N≤M C.N≤2M D.N≥2M 10.设因果稳定的LTI系统的单位抽样响应h(n),在n<0时,h(n)= ( )

(全)2021高考英语作文话题常用词汇及例文汇总3大主题

高考英语作文话题常用词汇及例文人物传记 名词类 chievement 成就,成绩,功绩; devotion 奉献; contribution 贡献; courage勇气,胆量; determination 决心; virtue 美德,品行; experience 经验,经历; wisdom 智慧 intelligence 智力,才智; talent 天才,天赋; inspiration 灵感; figure 体形,身材;

dignity 尊贵,高尚; humour (美humor)幽默,幽默感; volunteer 义工,志愿者 failure 失败; hardship艰难; disability 缺陷,障碍; 形容词类 cheerful 兴高采烈的; elegant 文雅的,优美的; pretty 漂亮的,标致的; plain 朴素的,简单的; ordinary 普通的,平常的; slim 苗条的 content愿意的,满意的; energetic 精力旺盛的; overweight 超重的,过重的;

confused 迷糊的; amazed 大为惊奇的; desperate 绝望的; ambitious 有雄心的; confident 自信的; creative 创造性的; outstanding优秀的,杰出的; intelligent 聪明的,有才智的; learned adj.博学的,有学问的; gifted有天赋的,有才华的; independent独立的; determined坚定的; kind-hearted 善良的gentle adj.温柔的; generous 慷慨的,大方的; grateful adj.感激的;

TOEFL Junior语法题小托福语言形式与含义教学教材

T O E F L J u n i o r语法题小托福语言形式与 含义

TJ时态题 官方指南 1. He ___ one of his other classes on a field trip to the aquarium this Saturday. A. take B. to take C. is taking D. was taken TJ语态题 1. A man’s wristwatch ___ in the lobby of Liugi’s Pizza Restaurant on Tuesday, February 16. A. finds B. finding C. has found D. was found 2. Given new technologies and advanced training techniques, ski jumping records will surely continue ___ A. are broken B. to be broken C. breaking them D. have been breaking 3. They ___ to provide a lot of living spaces, not for long, dangerous voyages. A. build B. are built C. have built D. are building TJ连词/介词/副词 1. _____ you were at basketball practice today, your teacher, Mr. Morris, called on the phone to talk with you. A.So B. While C. Because D. Although 2. _____ the construction , the front entrance to the science building will be closed. ____, all students will have to use the doors on the north side to enter the building. A. At B. On C. Over D. During A. As a result B. Even though C. All of a sudden D. On the other hand 3. Cuckoos, cowbirds, and widowbirds are three examples ___ birds that are brood parasites. A. of B. by C. for D. from 4. My mother asked me if I wanted anyone else to come, __ the first person I thought of was you! A. but B. and C. while D. therefore 5. Known throughout recorded history, they are __- used by people all around the world.

2017数字信号处理模拟题a答案

1. 两个有限长序列x1(n),0≤n ≤33和x2(n),0≤n ≤36,做线性卷积后结果的长度是 70 , 若对这两个序列做64点循环卷积,则圆周卷积结果中n= 6 至 64 为线性卷积结果。 2. 一线性时不变系统,输入为 x (n )时,输出为y (n ) ;则输入为2x (n )时,输出为 ; 输入为x (n-3)时,输出为 3. 若正弦序列x(n)=sin(30n π/120)是周期的,则周期是N= 8 4. 如果一台计算机的速度为平均每次复乘5μS ,每次复加0.5μS ,用它来计算512 点的DFT[x(n)],问直接计算需要多少时间,用FFT 运算需要多少时间。 1、 直接计算 复乘所需时间 62621510510512 1.31072T N s --=??=??= 复加所需时间()6610.51010.5105125110.130816T N N s --=???-=???= 所以12 1.441536T T T s =+= 2、用FFT 计算 复乘所需时间 66122512510log 510log 5120.0115222 N T N s --=?? =??= 复加所需时间662220.510log 0.510512log 5120.002304T N N s --=??=??= 所以120.013824T T T s =+=

6.设系统差分方程 y(n)=ay(n-1)+x(n) 其中x(n)为输入,y(n)为输出。当边界条件选为y(-1)=0时,是判断系统是否线性的、移不变的

7.用级联型结构实现以下系统函数,试问一共能构成几种级联型网络,并画出其中一种的信号流图。 ()() ()() 22 41 1.41()0.50.90.8Z Z Z H z Z Z Z +-+= -++

TOEFL junior词汇

absorb be absorbed in absorption attract attractive attraction abundant abundance redundant rich plentiful ample amplify amplifier adapt adopt adaptation adoption apt opt option optional compulsory optimistic optimism optimist pessimistic pessimism pessimist advance vi./n. advanced elementary intermediate advancement advantage and disadvantage strength and weakness advise

advice advise sb. against doing sth. advisable recommend counsel devise device agree agreement agree with= in agreement with come to an agreement disagree agreeable agriculture cultivate culture cultivate my mind the culture of mind and body alter change alternate Day alternates with night. alternately alternative alien alienate ancient ancestor antique contemporary angry anger be angry with sb. be angry about/at sth. furious rage irritate annoy

写作常用词语高级替换形容词篇

褒义形容词篇 重要的(important) vital['va?t(?)l] 【例句】She had found out some information of vital importance. 【翻译】她已经发现了一些至关重要的信。 crucial['kru??(?)l] 【例句】It is crucial that the problem is tackled immediately. 【翻译】立即着手解决这个问题是至关重要的。 prominent['pr?m?n?nt] 【例句】This considerable increase in investment played a prominent role in fueling economic growth. 【翻译】投资的较大幅度增加,对拉动经济增长发挥了明显作用。 cardinal['kɑ?d(?)n(?)l] 【例句】Respect for life is a cardinal principle of English law. 【翻译】尊重生命是英国法律最重要的原则。 优秀的(good) excellent['eks(?)l(?)nt] 【例句】She has always had a high reputation for her excellent short stories. 【翻译】她一直因其优秀的短篇小说享有很高的声望。 outstanding[a?t'st?nd??] 【例句】The girl who won the scholarship was quite outstanding. 【翻译】得奖学金的女孩是相当优秀的。 extraordinary[?k?str??dnri] 【例句】Her strength of will was extraordinary. 【翻译】她的意志力是非凡的。 remarkable[r?'mɑ?k?b(?)l]

相关文档
最新文档