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托福听力lecture的结构1. Lecture有结构托福听力的lecture基本上都是总分总的结构，即「引入话题——展开讨论——教授总结」，下面分点论述：1）引入话题其实托福听力lecture里面讲课的教授就跟大家碰到过的老师一样，有的喜欢直入主题，有的喜欢拉七杂八。
总的说来，lecture话题的引入方式有三种：•开门见山：啥也不扯，一言不合就开车，比如TPO1 Lecture2：Ok, let’s get started. Great. Today I want to talk abouta way in which we are able to determine how old a pieceof land, or some other geologic feature is –datingtechniques.•课程回顾：回顾上堂课的内容，然后再切入本堂课的内容；一般来说本次是上次的细化或者与上次的对比。
比如TPO5Lecture2：Last week, we covered some arguments against going back to the Moon. But there are compelling reasons in favor of another Moon landing too, um…not the least of which is trying to pinpoint the moon’s age.••啰哩吧嗦：有的教授实在是特别啰嗦，比如TPO2 Lecture2：Hi, everyone. Good to see you all today.【你也好啊】Actually,I expected the population to be a lot lower today. Ittypically runs between 50 and 60 percent on the day theresearch paper is due.【来的人多不好么，说明你受欢迎啊】Um, I was hoping to have your exams back today【啊，要放榜啦】, but, uh, the situation was that I went away forthe weekend, and I was supposed to get in yesterday at five, and I expected to fully complete all the exams by midnightor so, which is the time that I usually go to bed, but myflight was delayed, and I ended up not getting in untilone o’clock in the morning【你飞机晚点关我什么事啊】.Anyway, I’ll do my b est to have them finished by the nexttime we meet【开始上课吧，please】. OK. In the last class,we started talking about...【终于开始了…】不论是用哪一种引入方式，话题总是要出来的。
3.21 Consider the M/M/1/m system which is the same as M/M/1 except that there can be no more than m customers in the system and customers arriving when the system is full are lost. Show that the steady-state occupancy probabilities are given by()m n p m n n ≤≤--=+0,111ρρρ证明：方法1， 直接使用系统状态变化的马氏链去计算方法2，可以使用截断马氏链的结果去做3.55 Consider the feedback model of a CPU and I/O device of Example 3.19 with the difference that the CPU consists of m identical parallel processors. The service time of a job at each parallel processor is exponentially distributed with mean 1/μ1. Derive the stationary distribution of the system.Solution:3.57 Consider the network in Fig 3.39. There are four sessions: ACE, ADE, BCEF, and BDEF sending Poisson traffic at rates 100, 200, 500, and 600 packets/min, respectively. Packet lengths are exponentially distributed with mean 1000 bits. All transmission lines have capacity 50 kbits/sec, and there is a propagation delay of 2 msec on each line. Using the Kleinrock independence approximation, find the average number of packets in the system, the average delay per packet (regardless of session), and the average delay per packet of each session.Figure 3.39Solution ：参考P211， section 3.6.1详细过程略。
Words and Expressions in Each Unit Welcome Unitexchange n. 交换;交流vt. 交换;交流;交易;兑换lecture n. 讲座;讲课:;教训vi.(开)讲座;讲课vt. 训斥registration n.登记;注册;挂号register vt.＆vi. 登记;注册sex n. 性别female adj. 女(性)的;雌的n.雌性动(植)物;女子male adj. 男(性)的;雄的n.雄性动(植)物;男子nationality n. 国籍;民族nation n. 国家;民族;国民designer n.设计者design n.设计;设计方案vt.设计;筹划campus n. 校园;校区formal adj.正式的;正规的anxious adj.焦虑的;不安的annoyed adj.恼怒的;生气的annoy vt.使恼怒;打扰frightened adj. 惊吓的;害怕的p.m. abr. (源自拉丁语)下午;午后a.m. abbr (源自拉丁语)上年;午前;午夜至正午senior adj. 级别(或地位)高的n.较年长的人senior high school (美国)高中at last终于;最终outgoing adj. 爱交际的;外向的impression n.印象;感想impress vt. 使钦佩; 给…留下深刻的好印象vi.留下印象;引人注目make an impression留下好印象what if要是……会怎么样呢?guy n.小伙子;男人;家伙concentrate vi.＆.集中(注意力);聚精会神concentrate on集中精力于experiment n.实验;试验leave... alone不打扰;不惊动awkward adj.令人尬的;难对付的junior adj.地位(或职位、级别)低下的n.职位较低者;(体育运动中)青少年junior high school(美国)初级中学explore vt.＆vi.探索;物探confident adi.自信的;有把握的confidence n.信心;信任forward adv.( also forwards)向前;前进adj.向前的;前进的look forward to盼望;期待take notes记笔记flash n.光;信号vi.闪耀;闪光;发出信号vt.使闪耀;发出(信号) flash card 教学卡片;识字卡organise (NAME -ize) vt.组织;等备;安排;组建vi.组建;成立organisation (Nam -ization) n.组织;团体;机构goal n.目标;球门;射门strategy n.策略;策划partner n.同伴;配偶;合伙人improve vi.＆vt. 改进;改善curious adj. 好奇的;求知欲强的company n.公司;商行;伴personality n性格;个性style n.方式;作风revise vt＆vi.修改;修订;复习Unit 1teenage adj.十几岁的(指13至19岁);青少年的teenager n.(13至19岁之间的)青少年ballet n.芭蕾舞volunteer n志愿者debate n. 辩论;争论vt.＆vi.辩论;争论prefer vt.较喜欢prefer…to... 喜欢……多于......content n.内容; [pl]目录; (书、讲话、节目等的)主题movement n.动作;运动;活动greenhouse n，温室;暖房clean up打扫(或清除)干净suitable adj.合适的;适用的suitable for对……适合的actually adv.事实上;的确challenge n.挑战;艰巨任务vt.怀疑;向……挑战title n.(书、诗歌等的)名称; 标题;职称;头衔topic n.话题;标题freshman n ( especially NAmE）（中学)九年级学生;(大学)一年级新生confusing adj.难以理解的;不清楚的confuse vt.使糊涂;使迷感confused adj.涂的;迷感的fluent adj.(尤指外语)流利的;熟练的graduate vi.＆vt.毕业;获得学位n.毕业生recommend vt.建议;推荐;介绍sign up (for sth)报名(参加课程)advanced a.高级的;高等的;先进的advance n.前进;发展vi.前进;发展vt.发展;促进literature n.文学;:文学作品extra-curricular adj.课外的;课程以外的extra adj.额外的;附加的obviously adv.然:;明显地quit vi.＆vt.（quit，quit ）停止;戒掉:离开(工作职位、学校等）responsible adj.负责的;有责任的responsibility n.责任;义务be responsible for对负责solution n.解决办法;答案schedule n.工作计划;日程安排vt.安排;预定editor n.主编;编辑;编者plate n.盘子;子adventure n.冒险;奇遇youth n.青年时期;青春survival n.生存;幸存;幸存事物expert n.专家;行家adj.熟练的;内行的;专家的behaviour n.行为;举止generation n.一代(人)attract vt.吸引;引起………的注意(或兴趣)be attracted to喜爱focus vi.＆vt.集中(精力、注意力等);(使)调节焦距n.中心;重点;焦点focus on集中;特别关注addicted adj. 有瘾的;上瘾的;入迷的addict n. 对……入迷的人;吸毒成瘾的人addicted to对……很入迷adult n. 成年人adj.成年的;成熟的Chicago 芝加哥(美国城市)Seoul 首尔(韩国首都)Unit 2castle n. 城堡;堡全appy vi.＆vt.申请:请求vi. 应用;涂(油漆、乳剂) apply for申请visa n.签证rent vt .租用;出租vi.租用;租金为n. 租金pack vi.＆vt. 收给(行李）vt.包装n. (商品的)纸包;纸;大包amazing adj.今人惊奇的:今人惊喜的amazed adj.惊奇的；惊喜的arrangement n.安排:等备extremely adv，极其;非常source n，来源;出处narrow adj.狭窄的vi.＆vt.(使)变窄flat adj.平坦的;扁平的n.公寓;单元房powerful adj.强有力的;有权势的;有影响力的empire n.帝国emperor n.皇帝site n.地点;位置;现场take control of控制;接管official adj.官方的;正式的;公务的n.官员;要员recognise (NAME -ize) vt.辨别出;承认;认可type n.类型;种类vi.＆vt.打字flight n.空中航行;航班;航程accommodation n.住处;停留处;膳宿unique adj.唯一的;独特的;特有的path n.小路;路线;道路destination n.目的地;终点other than除……以外admire vt.钦佩;赞赏architecture n.建筑设计;建筑学architect n.建筑设计师brochure n.资料(或广告)手册package n.包;包装盒vt.将…包装好package tour包价旅游contact vt.联络;联系n.联系;接触civilisation n.文明;文明世界make up构成;形成soldier n.士兵;军人transport n .(NAmE usually transportation)交通运输系统vt.运输;运送hike vi.徒步旅行vt. 去......远足n.远足;徒步旅行economy n.经济;节约economic adj.经济(上)的;经済学的credit n.借款;信用;称赞;学分credit card信用卡detail n. 细节;详情;细微之处check in(在旅馆、机场等)登记check out结账离开(旅馆等）request n.(正式或礼貌的)要求;请求vt. (正式或礼貌地)要求;请求view n.视野;景色;看法sight n.景象;视野;视力statue n. 雕塑;雕像BCE (= before the Common Era)公元前tomb n.坟墓unearth vt.挖掘;发掘comment n.议论;评论vi.＆vt.发表意见;评论the Eiffel Tower 埃菲尔铁塔Neuschwanstein Castle 新天鹅堡Iceland 冰岛(国家名）Disneyland 迪士尼乐园Peru 秘鲁(国家名）the Andes Mountains安第斯山脉the Amazon rainforest亚马孙南林the Inca Empire印加帝国Machu Picchu 马丘比丘Spain 西班牙(国家名)Spanish n.西班牙语;西班牙人adj.西班牙的Cusco 库斯科(秘鲁城市)Lake Titicaca 的的喀喀湖the Uros 乌鲁斯人the Terracotta Army兵马俑Unit 3fitness n. 健康:健壮;适合soccer n. 足球;足球运动stadium n.(pl. stadiums or stadia) 体育场;运动场boxing n. 拳击(运动)badminton n，羽毛球运动marathon n.马拉松赛跑event n.比赛项目;大事;公开活动come along跟随;到达;进步;赶快ski adj. 滑雪的vi. 滑雪host vt.主办;主持n.主人;东道主;节目主持人track n. 跑道;足迹;铁路轨道vt.＆vi. 追踪;跟踪track and field田径gym n. 健身房;体育馆gymnastics n.体操(训练)work out锻炼;计算出;解决sweat vt.使出汗;出汗弄湿vi.出汗;流汗n. 汗水;出汗make it获得成功;准时到达legend n.传奇故事(或人物】;传说athlete n.运动员;运动健儿master n.高手;主人vt.精通;掌握set an example树立榜样honour n.荣誉;尊敬;荣幸glory n.荣誉;光荣;赞美medal n.奖章;勋章championship n.锦标赛;冠军赛;冠军称号champion n.冠军;忧胜者determination n.决心;决定apart adv.分离;分开;成碎片fall apart破裂;破碎;崩溃injure vt.使受伤:损害injured adj.受伤的;有伤的injury n. 伤害;伤captain n.(运动队)队长;船长:机长lose heart丧失信心;泄气graceful adj.优美的;优推的strength n.力量;体力failure n.失败;失败的人(或事物)give up 放弃;投降compete vi.竟争;对抗make sense有道理:合乎情理:表清楚pretend vt.＆vi. 假装:装粉pretend to do sth假装做某事even if/though即使:虽然million num. 一百万cheat vi.作弊;舞弊vt. 欺骗，蒙骗n. 欺骗手段;骗子audience n. 现众;听众positive adj.积极的;正面的;乐观的;肯定的slim adj.苗条的:单薄的diet n.规定饮食:日常饮食vi. 节食make a difference有作用或影响rather adv.相当;有点儿rather than而不是push-up n.( especially NAmE)俯卧撑cut..0ut停止做(或使用、食用); 剪下now and then有时;偶尔compare….with/to... 与…比较jog vi.慢跑n.慢跑stress n.压力;紧张;重音vt.强调;重读;使焦虑不安n. 焦虑不安error n. 错误;差错Unit 4disaster n.灾难;灾害tornado n. (pl.- oes or-0s)龙卷风;旋风drought n.旱灾;久早landslide n.( landfall ) (山地或悬崖的)崩塌;滑坡slide vi.＆vt (使)滑行;滑动tsunami n.海啸flood n.洪水;大量vi.淹没;大量涌入vt. 使灌满水;淹没volcanic eruption n. 火山明发magnitude n.(地)震级:重大rescue n.＆vt. 营救; 救援damage vt.损害;破环n. 损坏;损失destroy vt. 摧毁;毁灭evacuate vt.疏散;撤出vi.撤离helicopter n.直升机death n. 死;死亡affect vi.影响;(疾病)侵袭;深深打动shelter n.避难处;居所;庇护vt.保护;掩蔽vi.躲避(风雨或危险) crack n. 裂纹;裂缝vi.＆vt. (使)破裂as if似乎;好像;仿佛ruin n.＆vt.破坏;毁坏in ruins严重受损;破败不堪percent n.百分之...... adj.＆adv. 每一百中brick n.砖;砖块metal n.金属shock n.震惊;令人震惊的事;休克vt.(使)震惊;in shock震惊;吃惊electricity n.电;电能trap vt.使落入险境;使陷入圈套n.险境;陷阱bury vt.埋葬;安葬breathe vi.＆vt.呼吸revive vt.＆vi.复活;(使)苏醒revival n.振兴;复苏effort n.努力;艰难的尝试;尽力unify vi.＆vt.统一;(使)成一体wisdom n.智慧;才智context n.上下文;语境;背景suffer vt. 遭受;蒙受vi.(因疾病、痛苦、悲伤等)受苦volcano n.(pl.- oes or-0s) 火山erupt vi.＆r.(火山)爆发;(岩浆、烟等)喷出supply n.供应(量);补给; [pl]补给品vt. 供应;供给typhoon n.台风in the open air露天;在户外hurricane n.(尤指西大西洋的)飓风survive vi. 生存; 存活vt.幸存;艰难度过power n.电力供应;能量:力量;控制力tap vi.＆vt.轻即;轻;轻拍n.水龙头;轻叩;轻酸pipe n. 管子;管道whistle vi.吹口;发出笛声vt. 吹口哨n. 哨子(声);呼声emergency n.突发事件;紧急情况calm adj. 静的;沉着的vt. 使平静;使镇静aid n. 援助;帮助；救援物资vi.＆vt. 帮助；援助Kit n.成套工具;成套设备frist aid kit急放箱on hand现有(尤指助)crash vt.碰撞；撞击n. 撞车; 碰撞sweep vi&vt (swept，swept) 打扫;清扫sweep away 消灭；彻底消除wave n. 海浪;波浪vi&vt挥手；招手strike vi&vt. （struck，struck/stricken) 侵袭；突击；击打n. 罢工；罢课；袭击deliver vi&vt. 递送;传达vt.发表summary n.总结;概括;概要effect n. 影响;结果;效果length n.长;长度Ecuador 厄瓜多尔(国家名)Memphis 孟非斯(美国城市)Alberta 艾伯塔省(加拿大省份）Colombo 料伦坡(斯里兰卡首都)Sri Lanka 斯里兰卡(国家名)Indonesia 印度尼西亚(国家名)Thailand 泰国(国家名)Malaysia 马来西亚(国家名)Sumatra Island苏门答腊岛Chandra Theeravit 钱德拉·特拉维Unit 5Billion n. 十亿native adj.出生地的;本地的;土著的n.本地人attitude n. 态度;看法reference n.指称关系;参考refer vi.提到;参考;查调vt. 查询；叫……求助于refer to指的是;进;提到;查阅system n.体系;制度;系统despite prep.即使;尽管ups and downs沉浮；兴衰；荣辱factor n.因素;要素based adj. 以(某事)为基础的; 以……为重要部分(或特征)的base vt.以……为据点;以…为基础n. 底部；根据date back (to..) 追溯到bone n.骨头;骨(质)shell n.壳；壳状物symbol n.符号;象征carve vi.&vt. 雕刻dynasty n. 王朝;朝代variety n. (植物、语言等的)变体;异体;多样化major adj 主要的;重要的;大的n. 主修课程;主修学生vi.主修;专门研究no matter where, who, what, etc 不论……;不管......dialect n.地方话；方言means n.方式;方法;途径classic adj传统的;最优秀的;典型的n. 经典作品;名著regard n. 尊重;关注vt. 把……视为;看待character n. 文字;符号;角色;品质;特点calligraphy n.书法;书法global adj. 全球的;全世界的affair n.公共事务;事件;关系appreciate vt.欣赏;重视:感激;领会vi.增值specific adj.特定的;明确的;具体的CE 公元struggle n.＆vi.斗争;奋斗;搏斗tongue n.舌头;语言point of view观点;看法semester n.学期gas n.汽油;气体;燃气petrol n. ( NAmE gas)汽油subway n.( BrE underground)地铁apartment n.( especially NAmE)公寓套房pants n. [pl.] (BrE)内裤;短裤; ( especially NAmE)裤子beg vt.恳求;祈求;哀求equal n. 同等的人;相等物adj. 相同的;同样的gap n.间隔;开口;差距demand n.要求;需求vt.强烈要求;需要vi. 查问vocabulary n. 词汇description n.描写(文字);形容relate vt.联系;讲述relate to与…相关;涉及;谈到Korean n.朝鲜(或韩国)语; 朝鲜(或韩国)人adj.朝鮮(或韩国)的Danish n.丹麦语;丹麦人adj. 丹麦的Denmark 丹麦(国家名)Arabic n.阿拉伯语adj.阿拉伯语的;阿拉伯文学的FIFA abbr.(源自法语)国际足联；国际足球联合会。
solution词组solution的意思是“解决方案”，可以用来表示解决问题的方法或办法。
以下是一些与“solution”有关的词组：1.solution to a problem：问题的解决方案2.provide a solution：提供解决方案3.find a solution：找到解决方案4.implement a solution：实施解决方案5.effective solution：有效的解决方案6.viable solution：可行的解决方案7.elegant solution：优雅的解决方案8.simple solution：简单的解决方案以下是一些具体的例子：●The solution to the problem of climate change is to reduce our reliance on fossilfuels.●The company provided a solution to the customer's complaint.●The scientists found a solution to the disease.●The government implemented a solution to the housing crisis.●The new software is an effective solution to the company's security problems.●The business plan is a viable solution to the company's financial problems.●The engineer designed an elegant solution to the structural problem.●The teacher explained a simple solution to the math problem.solution还可以与其他词组搭配使用，例如：✧problem-solving solution：问题解决方案✧technical solution：技术解决方案✧creative solution：创意解决方案✧sustainable solution：可持续解决方案✧scalable solution：可扩展解决方案✧affordable solution：负担得起的解决方案✧efficient solution：高效的解决方案effective solution：有效的解决方案。
2019新版高中英语必修一词汇Welcome unit1. exchangen.交换；交流v.交换;交流;交易;兑换2. lecture n. 讲座;讲课;教训v.(开)讲座;讲课vt. 训斥3. registration n.登记；注册；挂号4. register v..登记;注册5. sex n.性别female adj.女(性)的;雌的n.雌性动（植）物；女子male adj.男(性)的;雄的n.雄性动（植）物；男子6. nationality n国籍;民族nation n.国家;民族;国民7. designer n.设计者8. design n.设计;设计方案设计；筹划9. campus n.校园;校区10. formal adj.正式的;正规的11. anxious adj.焦虑的;不安的12. annoyed adj.恼怒的;生气的annoy v.使恼怒;打扰13. frightened adj.惊吓的;害怕的14. a.m. (源自拉丁语) abbr. 上午p.m. (源自拉丁语) abbr. 下午15. senior adj. 级别(或地位)高的n.较年长的人senior high school(美国)高中16. at last 终于;最终17. outgoing adj. 爱交际的，外向的18 .impression n. 印象；感想Impress v.使钦佩；给…留下深刻的好印象v.留下印象；引人注目make an impression留下好印象19.what if要是……会怎么样呢?20.guy n.小伙子;男人;家伙21.concentrate V.&ⅵ.集中(注意力);聚精会神concentrate on集中精力于22.experiment n.实验;试验23.leave…,a lone不打扰;不惊动24.awkward adj.令人尴尬的;难对付的25.junior adj. 地位(或职位、级别)低下的n.职位较低者；（体育运动中）青少年junior high school(美国)初级中学26.explore v.&v.探索;勘探27.confident adj.自信的;有把握的confidence n.信心;信任28.forward ,adv.( also forwards)向前;前进adj.向前的;前进的look forward to盼望;期待29.take notes记笔记30.flash n.光;信号闪耀；闪光；发出信号v.使闪耀；发出（信号）flash card教学卡片;识字卡anise/organize .组织；筹备；安排；组建vi.组建；成立organisation/organization n.组织;团体;机构32.goal. n.点点标；球门；射门33.strategy n. 策略，策划34.partner n. 同伴，配偶，合伙人35.improve v. 改进，改善36.curious adj. 好奇的，求知欲强的pany n.公司，商行，陪伴38.personality n. 性格，个性39.style n. 方式，作风，款式40.revise n. 修改，修订，复习Unit 11.teenage adj.十几岁的(指13至19岁);青少年的teenager n.(13至19岁之间的)青少年2.ballet n.芭蕾舞3.volunteer n.志愿者4.debate n.辩论;争论v.辩论；争论5.prefer v.较喜欢prefer…to…喜欢…多于6.content n.内容;pl目录;（书、讲话、节目等的）主题7.movement n.动作;运动;活动8.greenhouse n,温室;暖房9.clean up打扫(或清除)干净10.suitable adj.合适的;适用的suitable for对…适合的11.actually adj.事实上;的确12.challenge n.挑战;艰巨任务V.怀疑;向……挑战13.title n.(书、诗歌等的)名称;标题；职称；头衔14.topic n.话题;标题15.freshman n. AmE（中学）九年级学生；（大学）一年级新生16.confusing adj.难以理解的;不清楚的confuse v.使糊涂;使迷惑confused adj. 糊涂的，迷惑的17.fluent adj.（尤指外语）流利的；熟练的18.graduate v.&v.毕业;获得学位n.毕业生19.recommend v,建议;推荐;介绍20.sign up (for sth.)报名(参加课程)21.advanced adj.高级的；高等的；先进的advance n.前进;发展vi.前进；发展.发展；促进22.literature n.文学;文学作品23.extra-curricular adj.课外的；课程以外的extra adj. 额外的;附加的24.obviously adv.显然;明显地25.quit vi& vt. quit, quit停止；戒掉；离开（工作职位、学校等）26.responsible adj.负责的;有责任的responsibility n.责任;义务be responsible for对……负责27.solution n.解决办法;答案28.schedule n.工作计划；日程安排v.安排;预定29.editor n.主编;编辑;编者30.plate n.盘子;碟子31.adventure n.冒险;奇遇32.youth n.青年时期;青春33.survival n.生存;幸存;幸存事物34.expert n.专家;行家ad.熟练的；内行的；专家的35.behaviour n.行为;举止36.generation n.一代(人)37.attract v.吸引;引起……的注意(或兴趣be attracted to喜爱38.focus v.集中（精力、注意力等）；（使）调节焦距n.中心;重点;焦点focus on集中;特别关注39.addicted adj.有瘾的;上瘾的;入迷的addict n.对…入迷的人;吸毒成瘾的人addicted to 对……很入迷40.adult n. 成年人adj. 成年的，成熟的41.Chicago 芝加哥42.Seoul 首尔Unit21.castle n.城堡;堡垒2.apply vi.&v.申请;请求v.应用；涂（油漆、乳剂）apply for申请3.visa n.签证4.rent v.租用;出租vi.租用;租金为n.租金5.pack v. 收拾(行李) vt.包装n.（商品的）纸包；纸袋；大包6.amazing adj.令人惊奇的;令人惊喜的amazed adj.惊奇的;惊喜的7.arrangement n.安排;筹备8.extremely adv.极其;非常9.source n.来源；出处10.narrow adj.狭窄的&vt.(使)变窄11.flat adj.平坦的;扁平的公寓；单元房12.powerful adj.强有力的;有权势的;有影响力的13.empire n.帝国emperor n.皇帝14.site n.地点;位置;现场15.take control of控制;接管16.official adj.官方的;正式的;公务的n.官员；要员17.recognise/recognize v.辨别出；承认；认可18.type n.类型;种类&v.打字19.flight n.空中航行;航班;航程20.accommodation n. 住处；停留处；膳宿21.unique adj.唯一的;独特的;特有的22.path n. 小路;路线;道路23.destination n.目的地;终点24.other than除…以外25.admire v.钦佩;赞赏26.architecture n.建筑设计；建筑学architect n.建筑设计师27.brochure n.资料(或广告)手册28.package n.包裹;包装盒vt.将……包装好package tour包价旅游29.contact v.联络;联系n.联系;接触30.civilisation/civilization n.文明;文明世界31.make up构成;形成32.soldier n.±兵;军人33.transport n.( AmE usually transportation)交通运输系统运输；运送34.hike v.徒步旅行.去…远足n.远足；徒步旅行35.economy n.经济;节约economic adj.经济（上）的；经济学的36.credit n.借款;信用;称赞;学分credit card信用卡37.detail n.细节;详情;细微之处38.check in（在旅馆、机场等）登记check out结账离开(旅馆等)39.request n.(正式或礼貌的)要求;请求vt.（正式或礼貌地）要求；请求40.view n.视野;景色;看法41.sight n..景象;视野;视力42.statue n.雕塑;雕像43.BCE(= before the Common Era)公元前44.tomb n.坟墓45.unearth vt.挖掘;发掘ment n.议论;评论vi.&v.发表意见；评论47.the Eiffel Tower埃菲尔铁塔48.Neuschwanstein Castle新天鹅堡49.Iceland 冰岛(国家名)50.Disneyland迪士尼乐园51.Peru 秘鲁(国家名)52.the Andes Mountains安第斯山脉53.the amazon rainforest亚马孙雨林54.the Inca Empire印加帝国55.Machu Picchu马丘比丘56.Spain 西班牙(国家名)Spanish n.西班牙语；西班牙人adj.西班牙的57.Cusco库斯科(秘鲁城市)ke Titicaca的的喀喀湖59.the Uros乌鲁斯人60.the Terracotta Army兵马俑Unit 31.fitness n.健康;健壮;适合2.soccer n.足球;足球运动3.stadium n. pl stadiums or stadia体育场；运动场4.boxing n.拳击(运动)5.badminton n.羽毛球运动6.marathon n.马拉松赛跑7.vent n.比赛项目;大事;公开活动e along跟随;到达;进步;赶快9.ski adj. 滑雪的vi滑雪10.host vt.主办;主持n.主人;东道主;节目主持人11.track n.跑道;足迹;铁路轨道t.&vi.追踪;跟踪12.track and field田径13.gym n.健身房;体育馆14.gymnastics n.体操;训练15.work out锻炼;计算出;解决16.sweat vt.使出汗;出汗弄湿出汗；流汗n.汗水；出汗17.make it获得成功；准时到达18.legend n.传奇故事(或人物);传说19.athlete n.运动员;运动健儿20.master n.高手;主人; vt. 精通掌握21.set an example树立榜样22.honour n.荣誉:尊数:荣幸23.glory n.荣誉;光荣:赞美24.medal n.奖章;勋章25.championship n.锦标赛；冠军赛；冠军称号champion n.冠军;优胜者26.determination n.决心;决定27.apart adv.分离;分开;成碎片fall apart破裂;破碎;崩溃28.injure v.使受伤;损害injured adj.受伤的;有伤的inJury n.伤害;损伤29.captain n.(运动队)队长;船长;机长30.lose heart丧失信心;泄气31.graceful adj.优美的;优雅的32.strength n.力量;体力33.failure n.失败;失败的人(事物)34.give up放弃;投降pete v.竟争;对抗36.make sense有道理:合乎情理;表述清楚37.pretend v.覆假装;装扮pretend to do sth假装做某事38.even if/ though即使;虽然lion num.一百万40.cheat vi.作弊;舞弊v.欺骗；蒙骗n.欺骗手段；骗子41.audience n.观众;听众42.positive adj.积极的；正面的；乐观的；肯定的43.slim adj.苗条的;单薄的44.diet n.规定饮食;日常饮食vi.节食45.make a difference有作用或影响46.rather adv.相当;有点儿rather than而不是47.push-Up n.( especially NAmE)俯卧撑48.cut...out停止做(或使用、食用);剪下49.now and then有时;偶尔pare…with/to….与……比较51.jog v.慢跑n.慢跑52.stress n.压力;紧张;重音vt. 强调;重读;使焦虑不安v.焦虑不安53.error n.错误;差错Unit41.disaster n.灾难;灾害2.tornado n.(p.- oes or-os)龙卷风;旋风3.drought n.旱灾;久旱ndslide n.( landfall)(山地或悬崖的)崩塌;滑坡5.side v.&v.(使)滑行;滑动6.tsunami n.海啸7.flood n.洪水;大量v淹没；大量涌入v.使灌满水;淹没8.volcanic eruption 火山喷发9.magnitude n.(地)震级;重大10.rescue n.&ⅵ.营救;救援11.damage v.损害;破坏; n. 损坏；损失12.destroy v.摧毁;毁灭13.evacuate vt.疏散;撤出vi.撤离14.helicopter n.直升机15.death n.死;死亡16.affect v.影响;(疾病)侵袭;深深打动17.shelter n.避难处;居所;庇护保护；掩蔽vi.躲避(风雨或危险)18.crack n.裂纹;裂缝vi.&ⅵ.(使)破裂19.as if似乎；好像；仿佛20.ruin n.&v.破坏;毁坏in ruins严重受损;破败不堪21.percent n.百分之adj.&adv.每一百中22.brick n.砖;砖块23.metal n.金属24.shock n.震惊;令人震惊的事;休克（使）震惊in shock震惊;吃惊25.electricity n.电;电能26.trap vt.使落入险境;使陷入圈套n.险境；陷阱27.bury vt.埋葬;安葬28.breathe v.&v.呼吸29.revive vt.&vi.复活;(使)苏醒revival n.振兴;复苏30.effort n.努力;艰难的尝试;尽力31.unify vi&v.统-;(使)成一体32.wisdom n.智慧;才智33.context n.上下文;语境;背景34.suffer v.遭受;蒙受v.（因疾病、痛苦、悲伤等）受苦35.volcano n.火山36.erupt v.&v.(火山)爆发;(岩浆、烟等)喷出37.supply n.供应(量);补给;[pl补给v.供应;供给38.typhoon n.台风39.in the open air露天;在户外40.hurricane n.(尤指西大西洋的)飓风41.survive v.生存;存活v.幸存；艰难度过42.power n.电力供应;能量;力量;控制力43.tap v.&v.轻叩;轻敲;轻拍n.水龙头；轻叩；轻敲44.pipe n.管子;管道45.whistle w.吹口哨;发出笛声.吹口哨n.哨子(声);呼啸声46.emergency n.突发事件;紧急情况47.calm adj.镇静的；沉着的使平静；使镇静48.aid n.援助;帮助;救援物资v.&v.( formal)帮助;援助49.kit n.成套工具；成套设备first aid kit急救箱50.on hand现有(尤指帮助)51.crash v.&vi.碰撞;撞击n.，撞车；碰撞52.sweep vt.&vi.( swept, swept)打扫;清扫sweep away消灭;彻底消除53.wave n海浪；波浪vi.&v.挥手;招手54.strike vi.&v.( struck, struck/stricken)侵袭;突击;击打n.罢工；罢课；袭击55.deliver v.&v递送;传达vt.发表56.summary n.总结;概括;概要57.effect n.影响;结果;效果58.length n.长;长度59.Ecuador厄瓜多尔(国家名)60.Memphis孟非斯(美国城市)61.Alberta艾伯塔省(加章大省份)62.Colombo 科伦坡（斯里兰卡首都)63.Sri Lanka斯里兰卡(国家名)64.Indonesia印度尼西亚(国家名)65.Thailand泰国(国家名)66.Malaysia马来西亚(国家名)67.Sumatra Island苏门答腊岛68.Chandra Theeravit钱德拉·特拉Unit 51.Billion n. 十亿2.native adj.出生地的；本地的；土著的n,本地人3.attitude n.态度；看法4.reference n.指称关系;参考refer vi.提到;参考;查阅V.查询求助于refer to指的是；描述；提到；查阅5.system n.体系;制度;系统6.despite prep,.即使;尽管7.ups and downs浮沉;兴衰;荣辱8.factor n.因素;要素9.based adj.以(某事)为基础的以…为重要部分（或特征）的base vt.以……为据点;以…为基础n.底部；根据10.date back (to…)追溯到11.bone n.骨头;骨(质)12.shell n.壳;壳状物13.symbol n.符号;象征14.carve vt.&vi.雕刻15.dynasty n.王朝;朝代16.variety n.(植物=语言等的）变体；异体；多样化；17.major adj. 重要的；大的n.主修课程；主修学生vi.主修；专门研究18.no matter where, who, what, etc.不论…；不管…19.dialect n.地方话;方言20.means n.方式；方法；途径21.classic adj.传统的;最优秀的;典型的n.经典作品；名著22.regard n.尊重;关注vt.把……视为;看待23.character n. 几文字；符号；角色；品质；特点24.calligraphy n.书法;书法艺术25.global adj全球的;全世界的26.affair n.公共事务;事件;关系27.appreciate v.欣赏;重视;感激;领会.增值28.specific adj.特定的:明确的;具体的29.CE(= Common Era)公元30.struggle n.&ⅵ.斗争;奋斗;搏斗31.tongue n.舌头;语言32.point of view观点;看法33.semester n.学期34.gas ( NAmE )n.汽油;气体;燃气petrol (BrE)n.汽油35.subway n.( BrE underground)地铁36.apartment ( especially NAmE)公寓套房37.pants n.[pl.](BrE)内裤;短裤;especially (NAmE)裤子38.beg vt.恩求;祈求;哀求39.equal n.同等的人;相等物adj.相同的；同样的40.gap n.间隔;开口;差距41.demand n.要求;需求v.强烈要求；需要Vi.查问42.vocabulary n.词汇43.description n.描写(文字);形容44.relate vt.联系;讲述relate to与…相关;涉及;谈到45.Korean n.朝鲜(或韩国)语;朝鲜（或韩国）人adj.朝鲜(或韩国)的46.Danish n.麦语；丹麦人adj. 丹麦的Denmark丹麦(国家名)47.Arabic n.阿拉伯语adj.阿拉伯语的；阿拉伯文学的48.FIFA abbr.(源自法语)国际足联;国际足球联合会。
CHARPER 12a. Describe what step-by-step procedure might be involved inside the network in making a telephone connection.Solution:1. The telephone number specifies an "address" where the receiver is located.e.g. 025 - the area code ( geographical region); 8349 - telephone office ;2480- theparticular location of receiver.2. Telephone number dialed, route determination , circuit established.3. A ringing tone of incoming call at destination;The setting up of telephone calls is discussed in Chapter 4.Reference : P8 Figure 1.5 the three phase of a telephone connection2b. Now consider a personal communication service that provides a user with a personal telephone number. When the number is dialed, the network establishes a connection to wherever the user is located at the given time. What functions must the network now perform in order to implement this service?Solution:personal telephone number is not tied to a specific location, instead associated withan equipment. Fixed location telephone number cannot establish a connection towherever the user is located at the given time.Reference: a cell phone. GSM.3. Explain how the telephone network might modify the way calls are handled to provide the following services:a. Call Display: the number and/or name of the calling party is listed on a screen before thecall is answered.Solution: Along with the request for connection setup, the system sends identifying information regarding the originator's phone.5. Suppose that network addresses are scarce, and are assigned, so that they are not globally unique; in particular suppose that the same block of addresses may be assigned to different organizations. How can the organizations make use of these addresses? Can users from two such organizations communicate with each other?Solution:1. unique address within the same organization, but no unique address across multipleorganizations.2. establish gateways to connect between their internal users and users in other networks.Globally gateway unique address across multiple organizations..10. Discuss the similarities between the following national transportation networks and a communications network. Is the transportation system more similar to a telephone network or to a packet network?Solution:Comparison: connection oriented or connectionless.Application: people and goods.14. The propagation delay is the time that is required for the energy of a signal to propagate from one point to another.a. Find the propagation delay for a signal traversing the following networksb. How many bits are in transit during the propagation delay in the above cases, if bits areentering the above networks at the following transmission speeds: 10,000 bits/second; 1 megabit/second; 100 megabits/second; 10 gigabits/second.Reference: delay-bandwidth product.15. IETF, RFC, internet Draft , Proposed Standard, Draft Standard, and StandardCHAPTER23. What difference does it make to the network layer if the underlying data link layer provides a connection-oriented service versus a connectionless service?Solution:1. connection-oriented: network layer setup connection before transfer of information. Framesare transferred correctly and in sequence by the data link layer, the network layer can then assume that the packets it sends to its neighbor traverse an error-free pipe.2. connectionless: Each frame is sent in unconfirmed manner (without acknowledgments orretransmissions). Network layer cannot make assumptions about the sequencing orcorrectness of the packets it exchanges with its neighbors.4. Suppose transmission channels become virtually error-free. Is the data link layer still needed?Solution:Framing, Flow control, MAC.5. Why is the transport layer not present inside the network?Solution:1. Providing functions compensation for the upper layer of end-system. In TCP/IP, IP - onlybest effort service. But TCP - reliable service required by applications2. connections establishment and error control on an end-to-end basis / at the edge ofnetwork.3. Allow multiple processes in the end systems to share a network service.10. Give two features that the data link layer and transport layer have in common. Give two features in which they differ. Hint: Compare what can go wrong to the PDUs that are handled by these layers.Solution:In common: recovery from errors; flow control; multiplexing.Difference:1. across the network vs. connected directly; so other different feature induced.2. framing vs. block/ byte stream.3. MAC11a. Can a connection-oriented, reliable message transfer service be provided across a connectionless packet network? Explain.Solution:e.g. transport layer →logical connection →by setting up state information →e.g. packetsequence number →provide transmission with error free, no duplication, in order.e.g. TCP/IP22. How does the network layer in a connection-oriented packet-switching network differ from the network layer in a connectionless packet-switching network?Solution:24. Suppose we need a communication service to transmit real-time voice over the Internet. What features of TCP and what features of UDP are appropriate?Solution:TCPAdvantage: connection-oriented service for real-time voice stream.Disadvantage: reliable service with retransmissions results in packet delay and jitter that can not be tolerated by real-time traffic.UDPFeature: Provides connectionless service and delivers packets quickly. On retransmission, but some degree of packet loss can be tolerated by voice.28. What is the difference between a physical address, a network address, and a domain name?Solution:See PPT or textbook.Which is used in the data link layer?Which is the logical address?Which is the name easier to remember?33. Suppose a computer is moved from one department to another. Does the physical address need to change? Does the IP address need to change? Does it make a difference if the computeris a laptop?Solution:Key: Globally unique NIC card, IP address→sub-network id and host id.CHAPTER 411. Calculate the number of voice channels that can be carried by an STS-1, STS-3, STS-12, STS-48, and STS-192. Calculate the number of MPEG2 video channels that can be carried by these systems.Solution:1. voice channel - 64 kbps; MPEG2 - 5 Mbps;2. STS-1 51.84Mbps; STS-3 155.52Mpbs; STS-12 622.08Mbps; STS-48 2.5Gpbs; STS-19210Gbps.25. Compare the operation of a multiplexer, an add-drop multiplexer, a switch, and a digital crossconnect.Solution:1. multiplexer, add-drop multiplexer reference to PPT or textbook2. switch－N inputs ×N outputs. (1) Each input to a switch contains a number ofmultiplexed connections. (2)These connections can be demultiplexed and routed to different output ports where they are aggregated prior to exiting the switch. (3)switches are configured using signaling3. digital cross-connect is similar to a switch except that it is semi-permanent, usuallyconfigured by network operators rather than signaling processes. Their configuration is also done on a larger time scale (days or weeks). Digital cross-connects provide a basic network topology on which routing can be applied.27. Consider the multistage switch in Figure 4.35 with N = 16, n = 4, k = 2.a. What is the maximum number of connections that can be supported at any given time?Repeat for k = 4 and k = 10.Solution:For N = 16, n = 4 and k = 2, we have the following switch architecture:(1)Find the bottleneck. k<2n-1 8connection at a time(2)If k=4, k<2n-1, unblocking if rearrangement the connection pattern every time a newconnection request is made. But blocking in other situation. 16×16(3) if k=10, k>2n-1, without blocking.b. For a given set of input-output pairs, is there more than one way to arrange theconnections over the multistage switch?Solution: k ways →number of mid-stage switch29. Consider the multistage switch in Figure 4.35 with N = 32. Compare the number of crosspoints required by a nonblocking switch with n = 16, n = 8, n = 4, and n = 2.Solution:non-blocking →k = 2n – 1;total number of crosspoints →2Nk + k(N/n)2.49. Explain where the following fit in the OSI reference model:Solutions:a. A 4 kHz analog connection across the telephone network.Physical Layer: analog signal exists only in the physical layer.b. A 33.6 kbps modem connection across the telephone network.Data-Link Layer: modem uses framing, flow-control, and error correction, MAC.c. A 64 kbps digital connection across the telephone network.Physical Layer: 64 kbps signal is analogous to the 4 kHz signal used over the twisted pair.CHAPTER 51. Explain the difference between connectionless unacknowledged service and connectionless acknowledged service. How do the protocols that provide these services differ?Solution:(1) acknowledged connectionless service: reliable delivery for upper layer; Application forsensitive to loss; underlying layer is inherently unreliable with high BER.(2)Unacknowledged connectionless service: simpler and faster communication; Applicationfor inherently reliable networks or higher layers that can tolerate information loss or higher layers built-in error recovery mechanisms.10. Discuss the merits of the end-to-end vs. hop-by-hop approaches to providing a constant transfer delay for information transferred from a sending end system to a receiving end system.Solution:Jitter in networks has two primary sources – variation in queuing delay and variation inpropagation delay.Hop-by-hop approaches can be used to deal with queuing delay variation, and end-to-end approaches are required to deal wit h path-length variation.23. see textbook P30640. P31852. Perform the bit stuffing procedure for the following binary sequence:1101111111011111110101 →11011111011011111011010153. Perform bit de-stuffing for the following sequence:11101111101111100111110 →111011111-11111-011111-54. Consider the PPP byte stuffing method. What are the contents of the following received sequence of bytes after byte destuffing:0x7D 0x5E 0xFE 0x24 0x7D 0x5D 0x7D 0x5D 0x62 0x7D 0x5E →0x7E 0xFE 0x24 0x7D 0x7D 0x62 0x7E68.For this question, one must just keep in mind that all frames always contain the address of the secondary station.Only C is right!CHAPTER 631. Use HDLC and Ethernet to identify three similarities and three differences between medium access control and data link control protocols. Is HDLC operating as a LAN when it is used in normal response mode and multipoint configuration?Similarities: Both medium access control and data link protocols deal with the transfer ofblocks of information across a “single hop” which can consist of a point-to-point line, amultipoint line, or a shared medium.…… look up in textbookDifferences: The main functionality of the MAC protocols is to coordinate the access ofmultiple nodes to a shared transmission medium. To do so, the MAC protocols implement contention resolution procedures.The data link layer protocols implement error control and flow control functions to provide reliable transmission. The MAC protocols do not implement these functions.The data link layer protocols such as HDLC are concerned with providing connection-oriented, connectionless, and acknowledged connectionless packet transfer services to the network layer. The MAC protocols only provide connectionless packet transfer.The data link control protocol often handles packet transfer only over a point-to-point link between two nodes, where medium access control is not required. However, themultipoint-to-point configuration is an exception. When HDLC operates in normal response mode, it in fact is implementing polling to control access to the medium.36. Suppose that 80 percent of the traffic generated in the LAN is for stations in the LAN, and 20 percent is for stations outside the LAN. Is an Ethernet Hub preferable to an Ethernet switch? Does the answer change if the percentages are reversed?The difference between a hub and a switch is that in the hub frame are broadcast to all lines, while in a switch, frames are forwarded to another collision domain only if the destination is in that domain.……42. Use IEEE 802.3 and IEEE 802.11 to discuss three differences between wired and wireless LANs.Error rate: high error rate due to interference and noiseStation mobility: stations ~ mobile and portable; dynamic traffic routing and service handoff ~ since the station moves from one service area to another.Collision detection: hidden station problemSecurity: wireless LAN ~ encryptionPower consumption: battery ~ limited power capacity ~ power efficient.47. Why is error control (ARQ and retransmission) included in the MAC layer in IEEE 802.11 and not in IEEE 802.3?reference to solution 42Chapter 77.3. Suppose a service provider uses connectionless operation to run its network internally. Explain how the provider can offer customers reliableconnection-oriented network service.1. establish logical connections before transportation2. packet sequence number →retransmit lost packets, delete duplicate packets, andrearrange out-of-order packet7.23. Consider the operation of a packet switch in a connectionless network. Whatis the source of the load on the processor? What can be done if the processor becomesthe system bottleneck?。
