Towards the ubiquitous computer A

Towards the ubiquitous computer:A mobile agent approach

Carlos Bobed Eduardo Mena

IIS Department IIS Department

Univ.of Zaragoza Univ.of Zaragoza

50018Zaragoza50018Zaragoza

cbobed@unizar.es emena@unizar.es

Abstract

New advances in mobile computing devices al-low us to think about new approaches such as a functional ubiquitous computer.In par-ticular,it would be very useful for users to move from one place to another having all his data and applications available,in the same state,and without doing anything special(a real ubiquitous computer).

In this paper we propose an infrastructure that makes the user independent from a spe-ci?c computer/location.The intelligent envi-ronment detects the location of the user and presents his computer workspace on the clos-est computer.The system?nds the optimal balance between remote and local access to user?les and applications,to reduce the use of remote resources whenever possible.This is achieved by using mobile agents that man-age the mobility of users.All the data(and applications’state)“move”wherever the user goes,giving him the impression of controlling a computer just by getting close to it.We have done some tests that proof the?exibility of our approach.

1Introduction

The idea of separating the user from the usual view he has of the computer has been round-ing around since Mark Weiser proposed to hide the computer in order to use it without notic-ing it[18].The goal of this paper is not to hide computers,but to become independent from a speci?c physical computer,thus users would

work on ubiquitous computers.

Mobility and independence are the ideas be-hind our proposal.The user should be able to move around just focusing on his work,and the state and all the data the user left in the last computer used must be available trans-parently in the new one.This virtual ubiqui-tous computer will instantiate in the nearest-to-the-user“physical”computer(whose com-putation power would be used).

Nowadays,there are some approaches that implement remote desktops(e.g.VNC[13], RDesktop[1,8])or use virtual machines that maintain their states(the Internet Sus-pend/Resume(ISR)project[7,16]).How-ever,these systems consume a great amount of network resources:the former has to refresh the image of the remote desktop continually (the local host only has to send keyboard and mouse events),and the latter has to send all the virtual machine state over the net.

To overcome the drawbacks of the previous approaches,we have designed an agent-based layer on top of the underlying OS that pro-vides users with the desired mobility capabil-ities without any change in the applications.

The user will have the same view of the system whatever computer he sits in front of,without having to do anything special to access all his ?les but to get near the computer.Manual lo-gin is not needed as the system detects users’location,by using an indoor-location system based on WiFi[15]:the user logs in automat-ically if the system decides so according to its prede?ned rules.Thus,in our system,physi-cal computers are intelligent terminals which 1

o?er themselves to users,who are not aware of the movement of his data and applications (a seamless movement).To achieve this,the system must transfer all the applications’state and keep the way the user works with his com-puter unaltered.

The rest of the paper is structured as fol-lows.In Section2,we present the agent-based mobile infrastructure that manages the users’movements.In Section3,we describe the tech-nological problems that our system must deal with.In Section4,we overview our prototype. In Section5,we review the related work.Fi-nally,in Section6,we draw some conclusions and future work.

2Mobile infrastructure

Two main requirements have led the design of the proposed mobile infrastructure.Firstly, when the user moves from one host to another, he has to?nd everything in the same state as it was on the previous host(applications,opened ?les,resources,con?gurations,...).Secondly, the local resources must be used as much as possible,avoiding to become a simple remote desktop application that consumes network re-sources continually.In this way,the usage of network is reduced and the response time of applications decreases.

To delimit the problem we deal with,we put three restrictions to our system:

1.All the available computers have the same

OS and installed applications.This al-

lows our system to move a user session

data without taking care of whether an

application is available on the target host

or not.

2.All the applications keep their state at

the moment when the user stops using

a computer.This allows the system to

transfer only this status information to re-

store the previous application state;this

assumption is based on the existence of

speci?c protocols for this session manage-

ment such as XDMCP[19].

3.A generic user is used to impersonate real

users.The system adapts this generic ac-

count depending on the user that takes

control of the host computer.

In the rest of the section,we present the be-havior of our system,the agent infrastructure proposed to reach our goals,and we describe how the system deals with user location.

2.1System behavior

Our system detects whether a user is ap-proaching to or going away from a computer and acts in the following way:

1.When the system detects that the user is

leaving a computer,it closes his session

after saving its state(all the data needed

to restore his session).Also,our system

stores information about the applications

left running in background.

2.When the user gets near of another avail-

able1computer,the system retrieves the

information about the user’s?les,makes

these?les transparently available to the

new host computer and logs the user au-

tomatically in(restoring the previous ses-

sion as the user left it).Finally,it for-

wards the display of the running applica-

tions the user left,if any,to the new host. Not all the user?les are transferred at once,but incrementally.When the user moves onto a new computer,only the most needed ?les(session,con?guration and some currently opened?les)are transferred there;the others are gradually and automatically sent as the user requests access to them.The user is not aware of this background process,so we man-age to deceive him and?nally have the most accessed?les on the new host(theoretically, we would?nish having all the?les available locally).So,these?les can be opened locally and then most of the work is done using the resources of the current computer.

2.2Agent infrastructure

The mobile infrastructure that manages the movements of the user is based on mobile 1Some computers could be being used by other users or access could be restricted for that user.

agents.A mobile agent is a program that executes autonomously on a set of network hosts on behalf of an individual or organiza-tion [10].Mobile agents execute in contexts denominated places .A mobile agent is able to pause its execution,travel from one place to another,and,once there,resume its execu-tion.

We distinguish three di?erent kinds of agents:Guardian ,MovementManager ,and UserAgent (see ?gure 1).The goals of each one

are:

Figure 1:Agents of mobile infrastructure

?The Guardian agent manages the re-sources of the host on which it resides (there is one Guardian in each host).It automatically logs the users in and out and keeps the users’resources’informa-tion up to date.?The MovementManager agent coordi-nates the movements of the (UserAgents )and the information interchanges across Guardian agents.There is one Move-mentManager in each host of our system.?The UserAgent follows the user from one host to another,carrying with it the user’s resources information updated.There is one UserAgent for each mobile user in our system.

2.3Managing the location of users

In our prototype,we use a WiFi indoor local-ization method to acquire the user locations which gives us a precision of two meters,use-ful enough for our purposes.The localization method is not the goal of this paper and de-tails can be found in [15];however,any other localization method could be used in our sys-tem.

We want the underlying movement infras-tructure (described in 2.2)independent from the particular way in which users are lo-cated.This is achieved by de?ning a loca-tion layer between these two modules (see ?g-ure 2).The location layer receives the user locations from the localization method and generates two kind of events,“user i is close to computer j ”(arrival event),“user i leaves computer j ”(departure event),which alerts the MovementManager agent on computer j when a user i gets close enough or leaves the computer j ,

respectively.

Figure 2:Managing the user location

The rules that guides the decision making process are very simple.A user can be in three possible states:out of range,near,and close to a computer.In our prototype,a user is near to a computer if his distance to it is smaller than 7meter,and he is close to the computer if it is within 3meter.A user must remain close to a computer for a prede?ned time to generate the corresponding event;similarly,he must remain in out of range state for a prede?ned time to generate a departure event.

When a MovementManager agent on computer j receives an arrival event,it requests the UserAgent of user i to travel to computer j

and forwards a login request to the Guardian agent on computer j;this Guardian agent will decide if user i is able to log in that computer. Similarly,when a MovementManager agent on computer j receives a departure event,it re-quests the Guardian agent on computer j to log user i out.

3Technological challenges

There are three main issues we have to deal with:how to make the?les accessible from any host and gradually transfer them to gain local access to them;how to make the applications follow the user,and how to keep the users’privacy.

3.1File accessibility

One of the hardest problems is to have all the user’s?les available for him at any time but trying to access them locally most of the times. If we do not want to stop the user accessing his?les when he moves to another host,the ?rst accesses must be remote.Our main idea is to make the?le operations smart enough so that they would be in charge of?nding where the needed?le resides(we propose a virtual ?le-system as described in?gure3).

We studied some existing remote?lesystems such as NFS(3.0)or AFS[5],but they do not provide local cache for the?les(NFS v4.0 is the?rst NFS version that implements it); some distributed?lesystems such as Coda[4] or Intermezzo[3]have been also studied,but the cache they provide is not persistent and they did not relieve us from the use of a“cen-tralized”cluster(we want to have host com-puters as free as possible).

Figure3shows how our virtual?le-system works.We have all the data about the?les in a special directory tree,which would be shown to the user;at the moment of access-ing the?les,the modi?ed functions would test whether the?le has been already brought to the local computer,or if it has to be accessed remotely.Once a?le is transferred to the local hard disk,it has to be tagged as local and have the remote copy erased.Meanwhile,the

local

Figure3:Our FS concept directories are?lled in background so,in the

end,almost every access would be local(theo-retically,all of them because of the progressive

background process).

In?gure3,the?le named B is tagged as remote and our?lesystem would access it re-motely,while the“A”?le has been already carried to the new local host and properly tagged as locally accessible(the remote“A”?le would be erased by a garbage collector).

3.2Movement of applications

The applications cannot be made travel from one host to another(we are not talking about just standalone plain processes,but applica-tions that can have resources that can’t be moved),but we desire to make the user have that view.We use the X-Windows system as underlying display system due to its separa-tion into XServers and XClients,which gave us more?exibility than other integrated dis-play systems(such as the model that Win-dows OS uses).We thought of changing the screen which the applications forward its win-dows into,but this could not be done because of two problems:

?The applications get the value of the en-

vironment variable DISPLAY(a variable

which tells them where to display their

windows)only at the moment they are

launched,so any later change of the DIS-

PLAY variable does not a?ect their read

value.

?The information of each window is stored in the server-side of the connection,the XClient accesses to it via an identi?er.Even if the application could change the DISPLAY value to the XServer in the new host,the new XServer would not have any idea of the information that is associated to the identi?ers that the client presents to it.We studied the use of a VNCServer to for-ward the windows to another hosts,but we found di?erent problems.A VNCServer is as-sociated to an XServer,so if we want to keep running all the applications of a user while he moves,we would have to keep the XServer alive.

This would lead us to make a decision be-tween:1)to keep n XServers running on each host of the system (one XServer for the win-dows of each of the n mobile users),or 2)to block completely the host to other users once a mobile user has entered it (in order not to mix di?erent users’windows into the same host).Neither of the options are

acceptable.

Figure 4:Our modi?ed XServer

We propose a modi?ed server (?gure 4)that behaves in three di?erent ways depending on who interacts with it:

1.It is a normal XServer to the local ap-plications,so they could run without any modi?cation.

2.It accepts movement requests from an ex-ternal party to forward the windows of the applications to the proper display.

3.It behaves as an XClient to the remote XServers which it forwards the windows into.The di?erent resources in the modi?ed XServer would have to be tagged as owned by the proper user.Having this server,we could make the applications give the sensation of movement to the user,without having to recode them.The Xdmx server 2behaves in a similar way but it would require to be modi-?ed to accept the movement requests and ?t exactly our wanted behavior.

3.3Privacy

Privacy is a very important issue when we deal with user’s pro?les,?les,con?gurations and autologins.There arose a problem with this matter when we had to manipulate a generic user to make it appear as the same one in dif-ferent hosts.

Due to this modi?cation of the generic user,all the mobile users are regarded as the same one for a unique host.This could be used by a malicious user to run an application to mon-itor other users in background (an eavesdrop attack).As the OS sees the application as being launched by the same user (the generic one),it would have the proper rights to access to all the actions of the next users that log in that host.We could control it at XServer level (with our modi?ed one),but not at OS level.There were two options:to kill all the user’s processes when he moves (unacceptable for us)or to modify the underlying OS to support a kind of mobile users.

So we propose a simple modi?cation which consists of adding a little tag to the structure of user identi?cation.This little tag could be used for controlling who is the real mobile user that is behind the generic user identity.Now,although its cost,by modifying the kernel of Linux,for example,we could control the access to the resources to support mobile users in a ?exible way and we could assure user’s privacy.

2

https://www.wendangku.net/doc/1d9316745.html,/

4Prototype

To implement our prototype,we had to relax some of the restrictions we had imposed to the system.

When we thought about how to manage the user’s ?les the ?rst option was to pack the user’s account (limiting it to a determined maximum size)and send it to the new host (just the brute-force solution).The option we have ?nally implemented is to divide the user’s account into two kinds of directories:static or mobile.Mobile directories are packed and travel with the UserAgent ,while static direc-tories are accessed always remotely.As we see in ?gure 5,?les can be both transparently ac-cessed locally or remotely depending on the class of their parent directory (properly tagged as mobile or static).This gives us the freedom to select which directories are going to travel in the next

move.

Figure 5:Transparent ?le access

The prototype (Nescrem )runs on Linux and has been implemented in Java,using the Grasshopper Agent platform [6]and KDE as Desktop Manager.Movement of the applica-tions has been delegated to them implement-ing the XSMP protocol (X Session Manage-ment Protocol [19]).Fortunately,almost every application in KDE and Gnome Desktop en-vironments implements it and that allows the system to move the state of the applications just moving the appropriate session ?les.

The results were more than acceptable.

When the user moved to the new host,he found all his ?les available,the desktop almost in the same state (most of the applications im-plement the XSMP protocol),and all the work done locally.In ?gure 6,we show the sum of load and response time (execution time)of some well known applications for remote ses-sion protocols (VNC and XDMCP)and the Nescrem prototype 3

.

Figure 6:Execution time of di?erent approaches (in seconds)

We now focus on session restoring time and bandwidth usage.Concerning restoring time,we see in ?gure 7that our system allows high mobility scenarios (imagine a user moving from one room to another).It must be noticed that the sizes showed in the ?gure are not the total user’s account size,only the transferred ?les (the system can decide whether to move or not a ?le dynamically,which allows us to have large user’s accounts,but only transfer initially a small part of it).The restoring time is linearly proportional to the size of the part of the account transferred.

The bandwidth test consists of monitoring two consecutive user sessions for 10minutes.The sessions involved opening the above men-tioned applications and doing some default ac-tions (editing or viewing some ?les,playing some games,and so on).As we can see in ?gures 8and 9,our approach consumes less bandwidth than the others.We only consume bandwidth when the user moves or when he

3

The test is performed in Pentium IV 2Ghz ma-chines 1GB RAM running GNU Debian OS

Figure 7:Session restoring times depending on the size of transferred ?les

accesses a ?le which has not been transferred yet.Both tests (response time and bandwidth usage test)have been performed over an Eth-ernet 100Mbps

network.

Figure 8:Bandwidth results (data received in a 10minutes session)

5Related work

In [7,16],they present the so-called ISR tech-nology (Internet Suspend/Resume)whose goal is the same as ours is.They work with vir-tual computers (VMWare machines 4)by send-ing all the system state over the Internet when the user moves,which nowadays make

4

https://www.wendangku.net/doc/1d9316745.html,/products/ws/

Figure 9:Bandwidth results (data sent in a 10minutes session)

their system not feasible to use in some high-mobility scenarios.Their approach is expen-sive in terms of bandwidth,resuming time (in their best case they have to send an average of 47MB and their response time falls to 45seconds over a 100Mbps network,and in their worst case all the VM state has to be trans-ferred incurring in a 43minutes session restor-ing time at the same network speed)and com-putational power (everything is executed in-side a virtual machine).Our approach is more ?exible to the user movement at the cost of loosing the seamlessness requirements.We also use all the computational power of every computer of our system when the user works with it.

With remote desktop technologies (such as VNC [13],Remote Desktop [12]-a opensource client for Microsoft’s RDP [8]-or Remote Ad-ministrator [11]),the user always uses the same computer.They transform the in-front computer in just a simple terminal to which the user’s computer forwards the desktop.Al-though they manage to show exactly the state of the desktop,the network dependence and the bandwith needed to refresh the remote desktop are high,and they do not really hide the use of the system to the user (he has to know how to work with remote desktops and has to control the movements by hand).Sun

o?ers SunRay[9],a more advanced remote desktop technology.It is a three layer system that makes independent the running applica-tions from the?nal client hosts.They allow to have di?erent OS applications being exe-cuted and forwarded to the same?nal client, but it shares the remote desktops drawbacks. Our system allows the applications run locally, avoiding the refreshing costs and response de-lays,and automatizes the movements. Google o?ers a web-based approach with its Google Docs project5.They provide some common applications(a word processor and spreadsheet editor)that can be accessed via web-browser.This approach make user change radically his view of the computer;and,what is more,the user does not have all its appli-cations available,having to adapt to the new tools.

Finally,other approaches propose to de-velop a middleware on which programming the ubiquitous software[2]from scratch,to create a new operating system which would be able to provide us with ubiquitous resources and behavior[14],or even to use mobile tasks[17]. But this was not what we were looking for,we did want to reuse all the existent applications without having to recoding them.

6Conclusions and future work

In this paper we have presented a system that gives the real feeling of using an ubiquitous computer:the user can access his?les,ap-plications and con?gurations at any time and from any computer.

The proposed technological infrastructure is enough to reach our goals and,although some issues are still open,the results we have reached with the prototype are very satisfac-tory.In particular,the resuming times we reached make it react very quickly to the user’s movements.

We have managed to make the movement of the account and applications of the user invis-ible.The advantages of our system system: 5https://www.wendangku.net/doc/1d9316745.html,

?The access to the user’s?les is not al-

ways remote or local:it varies dynam-

ically from remote to local as the user

moves depending on the rules de?ned.?Applications are executed locally.

?A high level of seamlessness in the move-

ments is achieved and the way the user

uses the computer is not changed.?And,?nally,we have reduced the resum-

ing time that other approaches reach[16]

by adopting some trade-o?s.

As future work,we plan to add the notion of domains to our system,di?erent environ-ments in which the user can be(his job,his home,...);and to study how to use comput-ers with di?erent software con?gurations(dif-ferent installed applications,di?erent desktop environments,...)in our system.We also plan to add more control features to raise the ?exibility of the users movements,i.e.allowing the users to specify the computers they wants to use.

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新课标英语七年级上册单词表(含音标)

初一人教版英语上册单词表 Starter good[] adj. 好的;令人满意的 morning[] n 早晨;上午 good[] morning[] 早上好！ evening[] n 晚上;黄昏 good[] evening[] 晚上好！ How[] adv.怎样;怎么;如何 are[] v. 是 you pron.. 你;你们 How[] are[] you 你(身体)好吗？ I[]. pron. 我 am[] v. 是 I'm =I[] am[] 我是 fine[] adj. 好的 thanks int. &n 谢谢 ok int. adv. & adj. 好;不错 name[] n 名字 list[] n 名单;列表 what pron. (疑问代词)什么;什么样的人(或事物) is[] v. 是 what's =what is[] this adj. pron.. 这;这个 in[] prep 表示表达方式,手段,,用,以 English[]. n 英语 an[] art. (元音前)一个(只，把…) it[] pron.. 它 it's= it[] is[] map[] n 地图 orange[] n 橘子 jacket[] n 茄克衫 key[] n 钥匙 quilt[] n 被子 pen[] n 钢笔 ruler n[] 直尺 Ｐ＝parking abbr. 停车(区) NBA = abbr. (美国)全国篮球协会 kg=kilogram[] n 公斤;千克 spell v.拼写;拼字 please[]. v.请 color[] n 色;颜色 red[] adj. 红(色)的 yellow adj. 黄(色)的 green[] adj. 绿(色)的 blue[] adj. 蓝(色)的 black[] adj. 黑(色)的 white adj. 白(色)的 and[] conj. 和;又;而且 UFO abbr. 不明飞行物 CCTV.abbr. 中央电视台 UN=United Nations[] abbr. 联合国 the art. 定冠词 Unit 1 my[] pron.. 我的 name[] n 名字 is[] v. 是 name's=name[] is[] clock[] n 时钟 I[] pron.. 我 am[] v. 是 I'm=I[] am[] 我是 nice[] a.好的;令人愉快的 meet[] v. 遇见;相逢 you pron.. 你;你们 what pron.. & adj. 什么; what's=what is[] your pron.. 你的;你们的 hello[] int. 喂 hi[] int. 嗨 his[] pron.. 他的 and[] conj. 和; her[] pron.. 她的 question[] n 问题;难题;询问;疑问 answer[] n 回答 look[] v. 看;望;看起来 first[] adj. 第一的 first[] name[] 名字 last[] a.最后的;上一个的 last[] name[] 姓氏 boy[] n 男孩 girl[] n 女孩 zero num. . 零 one[] num. 一; two num. 二 three num. 三 four[] num. 四 five[] num. 五 six num. 六 seven num. 七 eight[] num. 八 nine[] num 九 telephone n ， 电话 number[] n 数;数字 telephone number[] 电话号码 phone[] n 电话 phone[] number[] 电话号码 it[] pron.. 它 it's ＝It[] is[] card[] n 卡;卡片 ID[] card[] n 身份证 family[] n 家;家庭 family[] name[] 姓氏 Unit 2

人教版新目标英语课文翻译七年级上全一册

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Unit one My name is Gina. 教材分析 1．话题： Making new friends 2．功能目标： 1）使学生学会用英语介绍自己。 2）使学生学会用英语和别人打招呼。 3．文化目标： 1）让学生初步体会用英语和别人交流的感受，培养学生学习英语的兴趣。 2）通过对英文名字的介绍，对比中西方表达名字的不同，了解中西方文化的差异。 3）通过对西方一些成功人士英文名字的介绍，使学生了解成功是由不懈的 1

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高中英语必修2（人教版） Unit1 Cultural relics IN SEARCH OF THE AMBER ROOM Frederick William I, the King of Prussia, could never have imagined that his greatest gift to the Russian people would have such an amazing history. This gift was the Amber Room, which was given this name because several tons of amber were used to make it. The amber which was selected had a beautiful yellow-brown colour like honey. The design of the room was in the fancy style popular in those days. It was also a treasure decorated with gold and jewels, which took the country's best artists about ten years to make. In fact, the room was not made to be a gift. It was designed for the palace of Frederick I. However, the next King of Prussia, Frederick William I, to whom the amber room belonged, decided not to keep it. In 1716 he gave it to Peter the Great. In return, the Czar sent him a troop of his best soldiers. So the Amber Room became part of the Czar's winter palace in St Petersburg. About four metres long, the room served as a small reception hall for important visitors.

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人教版七年级英语上册知识点 Starter unit 1 Good morning! 1. 短语归纳： good morning 早上好good afternoon 下午好good evening 晚上好 name list 名单an English name 英文名字 2. 必背典句： （1））Good morning, Alice! 早上好，艾丽斯！ （2））Good afternoon! 下午好！ （3））Hi, Bob! 你好，鲍勃！ （4））Hello, Frank! 你好，弗兰克！ （5））Good evening 晚上好！ （6））—How are you? 你好吗？ —I ’m fine, thanks. How are you? 我很好，谢谢。你好吗？ —I ’m OK. 我很好。 3. 英语中常见的问候语 ①Hello! 你“好！”是比较随便、不分时间的一种问候语，通常用于打招呼、打电话。表示惊讶或引起对 方注意。对方应答仍用Hello! ②Hi! “你好！”的使用比hello！更随便，在青年人中使用更为普遍。 ③ Nice to meet you! ④ How do you do? 很高“兴见到你！”Nice to meet you, to或 o.者Me, too “见到你很高兴”用于初次见面 你“好！”用于初次见面，是非正式的打招呼用语。对方应答语应是“How do you do? ”How are you? 表示问候意为“你好吗？”，为询问对方身体状况的问候语，应答语一般是“I ’fm ine. Thank you. / I ’m very well. Thank you. / I ’m OK. 3. 大写字母的用法： ①在英语中，句子的第一个单词的第一个字母都应大写。Sit down, please. 请坐。 ②字母I 作人称代词时，意为“我”，在句中任何位置都必须大写。日常用语“OK”在句中任何位置都大写。I ’m a studen我t. 是一名学生。Is everything OK? 一切都好吗？ ③人名、地名、国名、某国人或某种语言等专有名词的第一个字母都必须大写。 Lucy 露西China 中国Beijing 北京Chinese 中国人 ④表示月份、星期、重要节日的名词的第一个字母必须大写。 May 五月Monday 星期一New Year’s Da元y 旦 ⑤电影名、书名、报刊、文章的标题等中的每一个实词（如：名词、动词、形容词、副词、数词）的 第一个字母一般大写。English Weekly 《英语周报》Titanic 《泰坦尼克号》

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Frederick William Ⅰ，the King of Prussia , could never have imagined that his greatest gift to the Russian people would have such an amazing history . This gift was the Amber Room , which was given this name because several tons of amber were used to make it . The amber which was selected had a beautiful yellow-brown colour like honey . The design of the room was in the fancy style popular in those days . It was also a treasure decorated with gold and jewels , which took the country's best artists about ten years to make . In fact , the room was not made to be a gift . It was designed for the palace of Frederick Ⅰ. However, the next King of Prussia , Frederick William Ⅰ,to whom the amber room belonged, decided not to keep it. In 1716 he gave it to Peter the Great. In return , the Czar sent him a troop of his best soldiers. So the Amber Room because part of the Czar's winter palace in St Petersburg.About four metres long, the room served as a small reception hall for important visitors . Later,Catherine Ⅱhad the Amber Room moved to a palace outside St Petersburg where she spent her summers. She told her artists to add more details to it .In 1770 the room was completed the way she wanted . Almost six hundred candles lit the room ,and its mirrors and pictures shone like gold. Sadly , although the Amber Room was considered one of the wonders of the world , it is now missing . In September 1941, the Nazi army was near St Petersburg . This was a time when the two countries were at war . Before the Nazis could get to the summer palace , the Russians were able to remove some furniture and small art objects from the Amber Room . However , some of the Nazis secretly stole the room itself . In less than two days 100,000 pieces were put inside twenty-seven woooden boxs . There is no doubt that the boxs were then put on a train for Konigsberg, which was at that time a German city on the Baltic Sea . After that, what happened to the Amber Room remains a mystery . Recently , the Russians and Germans have built a new Amber Room at the summer palace . By studying old photos of the former Amber Room , they have made the new one look like the old one .In 2003 it was ready for the people of St Petersburg when they celebrated the 300th birthday of their city . A FACT OR AN OPINION? What is a fact? Is it something that people believe? No. A fact is anything that can be proved. For example, it can be proved that China has more people than any other country in the world. This is a fact. Then what is an opinion? An opinion is what someone believes is true but has not been proved. So an opinion is not good evidence in a trial. For example, it is an opinion if you say “Cats are better pets than dogs”. It may be true, but it is difficult to prove. Some people may not agree with this opinion but they also cannot prove that they are right. In a trial, a judge must decide which eyewit nesses to believe and which not to believe. The judge does not consider what each eyewitness looks like or where that person lives or works. He/she only cares about whether the eyewitness has given true information, which must be facts rather than opinions. This kind of information is called evidence. Unit 2 AN INTERVIEW Pausanias, who was a Greek writer about 2,000 years ago, has come on a magical journey on March 18th 2007 to find out about the present-day Olympic Games. He is now interviewing Li Yan, a volunteer for the 2008 Olympic Games.

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Starter Unit 1

1b Listen and repeat. 1b 听录音并跟读。Conversation 1 1 对话听录音并跟读。2a Bob: Good morning, Helen! 鲍勃：早上好，海伦！i, j, k, l, m, n, o, p, q, r Helen: Hi, Bob! 海伦：嗨，鲍勃！听录音，根据所听到的顺序为2b Conversation 2 2 对话字母编号。Cindy: Good morning, Alice! 辛迪：早上好，艾丽斯！i, j, k, l, m, n, o, p, q, r Alice: Good morning, Cindy! 艾丽斯：早上好，辛迪！ 3a 听录音，为图片编号。Conversation 3 3 对话Dale: Hello, Frank! Hello, Eric! 戴尔：你好，弗兰克！埃里克！你好，一把钥匙一张地图 Frank/Eric: Good morning, Dale! /弗兰克埃里克：早上好，戴尔！2a Listen and repeat. 2a 听录音并跟读。一床被子一支钢笔a, b, c, d, e, f, g, h a, b, c, d, e, f, g, h 2b Listen and number the letters you hear [1-8]. 听录音，根据所听到的顺序为2b 一把尺子一个橙子字母编号。a, b, c, d, e, f, g, h a, b, c, d, e, f, g, h 3a Listen and number the pictures [1-3]. 一个杯子一件夹克衫 3a 听录音，为图片编号。Conversation 1 中的单词。3b 听录音，补全3a1 对话Dale: Good morning, Helen! 戴尔：早上好，海伦！Helen: Good morning, Dale! 海伦：早上好，戴尔！Conversation 2 2 对话Frank: Good afternoon, Eric! ，一把钥匙一把钥匙，K-E-Y 弗兰克：下午好，埃里克！Eric: Good afternoon, Frank! 埃里克：下午好，弗兰克！Conversation 3 一张地图，M-A-P,一张地图3 对话Alice: Good evening, Bob! 艾丽斯：晚上好，鲍勃！Bob: Good evening, Alice!一支钢笔一支钢P-E-N鲍勃：晚上好，艾丽斯！3c Listen to the conversation. Then practice it 听对话并与同伴练习3c with your partner. 一床被子Q-U-I-L-T一床被Cindy: Good afternoon, Dale!

新外研版七年级英语上册新课标解读

新课标解读 新外研版七年级上册英语 Module 1 一．新课标要求掌握的词汇： Chinese ,from , Where, year, about, America, England, America, our, grade, be from,, twelve years old everyone, capital, The capital of , but, very , big , city , small, first name , last name . 二．新课标要求掌握的拓展短语： be from = come from What about you? = How about you? first name = given name 名字last name = family name. 三．新课标要求掌握的语法： P47 9 动词（2）系动词 四．话题项目： P95 1 个人信息2个人情况 本模块是对My classmates 的学习和训练是进入初中英语学习阶段的第一课，为整个学期的学习打基础 Module 2 一、新课标要求掌握的词汇： 1、* aunt [ɑ:nt] n. 阿姨；姑妈；伯母；舅妈 2、* brother ['br?e?] n. 兄弟 3、* cousin ['k?z?n] n. 堂兄弟姊妹；表兄弟姊妹 4、* daughter ['d?:t?] n. 女儿 5、* family ['f?mili] n. 家庭；家族 6、* father ['fɑ:e?] n. 父亲，爸爸 7、* grandfather ['ɡr?nd,fɑ:e?] n. （外）祖父 8、* grandmother ['ɡr?nd,m?e?] n. （外）祖母 9、grandparent ['ɡr?nd,pε?r?nt] n. （外）祖父母 10、* mother ['m?e?] n. 母亲，妈妈

英语必修二课文原文

人教版新课标必修2u n i t1课文原文和翻译w o r d格式 IN SEARCH OF THE AMBER ROOM Frederick William Ⅰ，the King of Prussia , could never have imagined that his greatest gift to the Russian people would have such an amazing history . This gift was the Amber Room , which was given this name because several tons of amber were used to make it . The amber which was selected had a beautiful yellow-brown colour like honey . The design of the room was in the fancy style popular in those days . It was also a treasure decorated with gold and jewels , which took the country's best artists about ten years to make . In fact , the room was not made to be a gift . It was designed for the palace of Frederick Ⅰ. However, the next King of Prussia , Frederick William Ⅰ,to whom the amber room belonged, decided not to keep it. In 1716 he gave it to Peter the Great. In return , the Czar sent him a troop of his best soldiers. So the Amber Room because part of the Czar's winter palace in St four metres long, the room served as a small reception hall for important visitors . Later,Catherine Ⅱhad the Amber Room moved to a palace outside St Petersburg where she spent her summers. She told her artists to add more details to it .In 1770 the room was completed the way she wanted . Almost six hundred candles lit the room ,and its mirrors and pictures shone like gold. Sadly , although the Amber Room was considered one of the wonders of the world , it is now missing . In September 1941, the Nazi army was near St Petersburg . This was a time when the two countries were at war . Before the Nazis could get to the summer palace , the Russians were able to remove some furniture and small art objects from the Amber Room . However , some of the Nazis secretly stole the room itself . In less than two days 100,000 pieces were put inside twenty-seven woooden boxs . There is no doubt that the boxs were then put on a train for Konigsberg, which was at that time a German city on the Baltic Sea . After that, what happened to the Amber Room remains a mystery . Recently , the Russians and Germans have built a new Amber Room at the summer palace . By studying old photos of the former Amber Room , they have made the new one look like the old one .In 2003 it was ready for the people of St Petersburg when they celebrated the 300th birthday of their city . A FACT OR AN OPINION What is a fact Is it something that people believe No. A fact is anything that can be proved. For example, it can be proved that China has more people than any other country in the world. This is a fact. Then what is an opinion An opinion is what someone believes is true but has not been proved. So an opinion is not good evidence in a trial. For example, it is an opinion if you say “Cats are better pets than dogs”. It may be true, but it is difficult to prove. Some peo ple may not agree with this opinion but they also cannot prove that they are right. In a trial, a judge must decide which eyewitnesses to believe and which not to believe. The judge does not consider what each eyewitness looks like or where that person lives or works. He/she only cares about whether the eyewitness has given true information, which must be facts rather than opinions. This kind of information is called evidence. 人教版新课标必修2 unit2 课文原文word格式 AN INTERVIEW Pausanias, who was a Greek writer about 2,000 years ago, has come on a magical journey on March 18th 2007 to find out about the present-day Olympic Games. He is now interviewing Li Yan, a volunteer for the 2008 Olympic Games.