Experiences with a Tool for Prototyping and Simulating Mobile Network Protocols
Experiences with a Tool for Prototyping and Simulating
Mobile Network Protocols
Ricardo Couto Antunes da Rocha,Markus Endler
1Laboratory for Advanced Collaboration
Departamento de Inform′a tica–PUC-Rio
Rua Marqu?e s de S?a o Vicente,225–G′a vea
22453-900–Rio de Janeiro–RJ
{rcarocha,endler}@inf.puc-rio.br
Abstract.Due to host mobility and intermittent connectivity the development
of distributed protocols for mobile computing is usually more complex than for
conventional networks.In this article we describe our experience with M OBI CS,
a simulation-based environment that provides support for prototyping,testing
and evaluating the complexity of distributed protocols.The key features of
M OBI CS are its?exibility for de?ning customized simulation models that are
compatible with the level of abstraction of the protocol to be tested and its sim-
ulation transparency.
1.Introduction
Mobile networks are characterized by a dynamic network topology,where connectivity patterns and transmission rates change very fast either because of host mobility,wireless bandwidth or resource shortages at the mobile hosts.Due to these dynamic characteristics, the development and analysis of distributed programs for such environments is even more dif?cult than for a static network.The main reason is that the underlying distributed protocols are intrinsically more complex than the equivalent protocols for conventional networks,where the main problems are due to the fact that part of the distributed state may become unreachable(e.g.a wireless disconnection)and that the connectivity pattern among the hosts is dynamically changing.
This dif?culty calls for tools that facilitate the prototyping and testing of dis-tributed protocols for different mobility and connectivity patterns.Many protocol simulators have been developed for mobile computing,such as[Bajaj et al.,1999, Zeng et al.,1998].These differ with respect to simulation performance,?exibility and the network characteristics being modeled.This article describes M OBI CS,a distributed protocol simulator for mobile computing that facilitates the prototyping and testing of protocols based on high-level programming abstractions and simulation transparency.
M OBI CS provides means for?exible and modular programming of distributed protocols.It also supports interchangeable simulation modes without affecting the dis-tributed protocols being prototyped.Our work on M OBI CS was motivated by the goal of developing a single tool both for testing the correctness of a protocol and for evaluating its performance in a simulated environment,so we developed a stochastic and a deterministic simulation mode.M OBI CS assumes a structured mobile network,composed by mobile hosts and mobile support stations,as opposed to ad-hoc networks.We are developing a extension called M OBI CS2to simulate protocols in ad hoc networks(see section4).
M OBI CS can be used to simulate many distributed protocols for mobile networks,such as[Acharya and Badrinath,1993],[Alagar and Venkatesan,1994],and
[Endler et al.,2000].These protocols explicitly take into account host mobility and lo-cation,as well as disconnections.M OBI CS has been successfully used for prototyping and evaluating mobile protocols since2000,in several Brazilian universities.
The remainder of the article is structured as follows:In section2we give an overview of M OBI CS functionalities.In section3,we discuss the protocol programming model adopted in M OBI CS.In section4,we present some additional tools and extensions developed to improve M OBI CS capability.In section5we discuss some experiences obtained from M OBI CS’use.In section6,we compare M OBI CS with some well known simulation tools and in section7we enumerate some?nal remarks of this paper.
2.Overview of MobiCS
M OBI CS is a Java class library that allows the user to implement a distributed protocol, the elements of a mobile network,and some interesting mobility models to test his(or her)protocol.The user of M OBI CS has just to extend some basic classes,implement interfaces and include the produced classes to build a runnable program,the simulator. M OBI CS provides a simulation framework,instead of a simulation environment,that eases constructing a simulation.Consequently,a user does not really runs M OBI CS but he constructs a M OBI CS-based simulation.
M OBI CS is structured as a layered software architecture that facilitates the design, prototyping and testing of distributed protocols with different and interchangeable simu-lation engines.Currently,M OBI CS supports simulation engines for a deterministic and a stochastic mode,but its architecture is?exible enough to allow also the implementation of completely different simulation engines.
M OBI CS is licensed under GPL software license and is freely available at https://www.sodocs.net/doc/d315583005.html,p.br/～mobics.
2.1.Deterministic Mode
The deterministic simulation mode is intended as a tool for testing and evaluating the correctness of the distributed protocol.In this mode,M OBI CS executes according to a simulation script describing a speci?c scenario for which a distributed protocol is to be tested.The script describes events generated by the application(e.g.a new request)and by the network elements(e.g.migrations,disconnections,etc.).
In the deterministic mode there is no notion of time.Simulation is executed in lock-step,and the partial order among event occurrences is made explicit in the script. The lack of time in this mode thus makes the simulated elements behave as if they had in?nite processing capacity and actions were instantaneous.The order of events is con-trolled by global and local synchronization points.A local synchronization point de?nes when a simulated element is able to process messages of a speci?c(or any)type.Global synchronization points are used to group concurrent(parallel)events and de?ne the causal order between events of different steps.
2.2.Stochastic Mode
The stochastic simulation mode is useful for testing a protocol with respect to its behavior and performance in a larger,continuous and more realistic scenario.In this mode,the behavior of the network elements is random or based on probabilistic parameters that de?ne the simulation scenario.Other than in the deterministic mode,where the simulation is script-driven,in this mode there is a notion of simulated time,and simulation is driven by random events generated according to a user-programmed speci?c simulation model.
The parameters of this model are the probabilities which determine the generation of the simulation events.
The user can program how each event(e.g.mobility,message sending)will be generated when the simulation starts.The pattern of each event generation com-prises the simulation model adopted to the protocol simulation.M OBI CS library also allows the user to specify how a protocol will be evaluated.For example, in[da Rocha and Endler,2001]we evaluated a protocol based on the ratio between the number of sent messages and the number of control messages.For such simulation,we speci?ed four simulation parameters:cell attraction,cell’s neighborhood,mobility ra-tio and wireless communication ration(see[da Rocha,2001]for more details).Other M OBI CS-based simulations[Ribeiro and M.Endler,2003,dos Santos Lima et al.,2003] have used a different evaluation method.A simulation model is also implemented in Java, extending some M OBI CS base classes.
2.3.Output
The basic output of a M OBI CS simulation is a log containing all ordered M OBI CS events and internal protocol messages.The user can evaluate this log to check if the protocol behavior is consistent for the simulated scenario.The user can still receive exceptions when some protocol’s property is violated.
In some cases,inspecting directly the log output can be harder to debug a pro-tocol,so a user can use an additional tool described in section4to help the graphical visualization of each event generation.
A complete and detailed example of M OBI CS simulation can be found in[da Rocha,2001].
3.Protocol Programming Model
M OBI CS’design focuses development and simulation of distributed protocols.Dis-tributed protocols are distributed algorithms that implement some form of coordination (synchronization and communication)among several processes in a network,and which usually assume the existence of reliable naming and network services.Several distributed protocols have been proposed for mobile computing(e.g[Acharya and Badrinath,1993, Maia et al.,2003,Endler et al.,2000]),for either structured or ad hoc mobile networks.
Although M OBI CS can be used also for prototyping lower-level,peer-to-peer pro-tocols,its main purpose is to support the development and testing of distributed protocols for structured mobile networks based on indirect model[Badrinath et al.,1993].
In M OBI CS,a protocol is programmed in a message-driven programming model: a user speci?es message handlers responsible to handle a speci?c message when it is received in a simulated element.A message handle is implemented as a class method using the pattern on
Protocol execution model is sequential,i.e.for a simulated element just a message can be handled per time.As result,a message handle is executed atomically.
4.MobiCS2and Additional Tools
Over the years,some additional tools have been developed in order to improve M OBI CS simulation capabilities.
The most complex of these tools is M OBI CS2[Mele,2002],a simulation tool for mobile ah hoc network protocols under development at PUC-Rio.M OBI CS2is a tool totally independent from M OBI CS,but uses its same architecture and protocol pro-gramming model.For example,M OBI CS2also implements stochastic and deterministic simulation modes.
The design decision of creation of a new simulation tool,instead of implementing changes in M OBI CS library,is due to some requirements of ad hoc network simulation. In M OBI CS2all physical structures and communication had to be remodeled,to avoid some limitations and simpli?cations introduced by M OBI CS.M OBI CS2supports devel-opment and composition of lower-level layer protocols,especially physical and transport layer protocols,and more complex simulation models.M OBI CS2also allows the user to implement energy consumption and connectivity models.Additionally,M OBI CS2library contains a minimal set of protocols for support ad hoc network simulation.
We have modeled IEEE802.11MAC layer and DSR(Dynamic Source Route) protocol using M OBI CS2.For more details about M OBI CS2and initial simulation re-sults,please refer[Mele,2002].M OBI CS2is still under development.
SLAT-Simple Log Animation Tool-is a Perl/Tk script that creates graphical animation of a M OBI CS-based simulation.SLAT reads a log?le containing the output of a deterministic or stochastic simulation and a con?guration?le and generates a graphical animation.SLAT con?guration?le is a XML?le containing the simulated environment con?guration and patterns of events to be animated.For each event,the user de?nes the correspondent visual action to be executed(e.g.a change of color for a visual element). SLAT is similar to Nam[Estrin et al.,2000]tool,used with the ns simulator.
GRAWP is an extension of M OBI CS which supports a Random Waypoint Mobility model for mobile hosts,presenting the elements(e.g.mobile hosts,mobile support sta-tions and cells)in a graphical canvas.Instead of requiring the user to program movement events,GRAWP generates these events based on this mobility model and some parame-ters con?gured by the user.This extension substitutes the traditional M OBI CS stochastic simulation.
5.Experiences
This section discusses experiences we obtained using M OBI CS for protocol programming and simulation.
https://www.sodocs.net/doc/d315583005.html,e
M OBI CS has been successfully used for teaching and research purposes at three Brazilian universities(IME-USP,PUC-Rio and UFMG)since2000.Several mo-bile computing protocols have been simulated using M OBI CS such as mobile multi-casting[Acharya and Badrinath,1993,Endler,1999,Maia et al.,2003],mobile IP,QoS management[dos Santos Lima et al.,2003],consensus[Badache et al.,1999],replica-tion[Alagar et al.,1995]and cache management.Some of these protocol simulations are available at M OBI CS home page[da Rocha and Endler,2005].
5.2.Protocol Programming
Our experience has shown that M OBI CS programming model eases development of pro-tocol prototypes,so a user can develop protocol prototypes in M OBI CS faster then in simulators like ns.In M OBI CS,the protocol developer can focus only on the algorithmic details and uses a popular programming language(Java),which offers well suitable data
structures and APIs for general purpose tasks.In most cases,a protocol can be developed from its speci?cation without requiring the addition of any simulator-speci?c details.
Although a protocol uses Java object oriented constructions,M OBI CS program-ming model is message-driven(see section3)and sequential.Consequently,a protocol has some properties different than a usual Java program.For example,a common mistake of new users of M OBI CS is the attempt to use threads,generating a non-deterministic behavior of a protocol.Since the protocol execution model is sequential,a protocol is not thread safe.Other programming mistakes have been observed as result of adoptioning the message-driven programming model,under the Java programming model.
We identi?ed that a suitable prototyping tool must allow the user to make general assumptions about the protocol and the environment behavior,in order to simplify the protocol development.In mobile computing simulations,hand-off atomicity is an im-portant example of such assumptions.Since hand-off in M OBI CS is always non-atomic, users experienced several protocol errors when developing early stage prototypes because they were not concerned with the possibility of occurrence of events before hand-off com-pletion.In order to develop simpler prototypes,a user could specify hand-off atomicity as an assumption and avoid having to solve this kind of errors.
5.3.Protocol Analysis
Experiences with protocol simulation and analysis have shown the usefulness and?exi-bility of two M OBI CS simulation modes.
The deterministic mode has been useful for debugging and identi?cation of pro-tocol inconsistencies.The mechanisms of exceptions and assertives have been useful for detecting error conditions and violations of protocol properties.As result,we could iden-tify inconsistencies in the MMA protocol[Suh et al.,2001],during a graduate course, and propose a more robust algorithm[Maia et al.,2003].Notice that the correction of the MMA protocol was not previously planned in such course.
Deterministic simulation works as a unit testing approach for protocols because it allows the developer to specify some conditions and check if the expected result has been achieved for such conditions.In this simulation,a condition to test is a distributed execution state of a protocol,instead of just a local execution state(typically a method’s result),tested in a traditional unit testing approach.
Deterministic simulation can be useful even to detect non-deterministic errors.It occurs because the behavior of a simulated environment between two simulation steps,in terms of total message order,can be non-deterministic.This situation also can be observed in a stochastic simulation but in a deterministic one the developer has more understanding about the global simulation scenario and can detect more precisely the origin of the errors.
Stochastic simulations are often used for performance evaluation.M OBI CS pro-vides a?exible API allowing the user to program his own simulation model(especially mobility model)and performance analysis model.This capability is valuable in simu-lation tools,especially for mobile computing,because each simulated environment has an own behavior(e.g.the mobility pattern of mobile phone users may be different than users in a building).We still can mix these two techniques and create a STRESS-like test[Helmy and Estrin,1998],using stochastic simulation and assertives inside a proto-col code.Therefore,stochastic simulation can also be used for debugging purposes.
More details about M OBI CS evaluation can be found in[da Rocha,2001].
https://www.sodocs.net/doc/d315583005.html,parison with other Simulation Tools
Some already existing network simulators have been extended and new,speci?c simula-tors have been developed for simulating mobile computing environments.Some of the most well known simulators for mobile computing are ns e GloMoSim.
In general,development of simulators is driven by the trade-off between proto-col programming abstraction and simulation performance.Table1summarizes the main differences among M OBI CS,ns and GloMoSim,according to aspects like goals,exten-sibility and protocol programming abstractions.For a more detailed comparison among M OBI CS and other simulators,please refer to[da Rocha,2001].
GloMoSim ns M OBI CS Evaluated Aspect Protocol Protocol Protocol/Algorithm
Goal Performance Performance Prototyping,testing,performance Algorithm/Protocol↓Transport↓Transport Distributed Protocols Protocol Implementation Parsec OTcl/C++Java Programming Abstractions/
Limited,Functions OO OO/μProt Modularization
self,con?gurable self,con?gurable Programable Mobility and Simulation
Models
Correctness Evaluation—STRESS,limited deterministic mode,generic Extensibility—yes yes
Table1:Comparison Table among Different Simulators
ns[Bajaj et al.,1999]is a?exible network protocol simulator that supports large scale simulations of interacting protocols within a stack of protocols.ns can also be used as a network emulator,which is able to interact with a real network.It comes with a gen-erator of scenarios,which automatically generates network topologies,traf?c and failure patterns,test situations.ns was implemented in a two-level programming model:the simulation kernel was implemented in C++and interacts with programs programmed in OTcl,an object-oriented extension of Tcl.While the kernel implements the simulation primitives,OTcl is used to implement scripts describing the protocols and the functional-ity of the simulated network elements in a high-level programming language.Because of this programming model,ns is a very?exible,extensible and general-purpose protocol simulator.
GloMoSim[Zeng et al.,1998]is composed of a collection of library modules for the parallel simulation of mobile networks and PARSEC,a C-based language for describ-ing parallel simulation.GloMoSim implements a set of protocols for wireless commu-nication,which are organized in a layered protocol architecture.It also supports easy modi?cation or extension of the protocols and modules written in PARSEC.The core of PARSEC implements a high-performance simulation engine,which allows GloMoSim to support the simulation of large-scale mobile computing networks with total simula-tion transparency,both for the protocol programmer and the user of the simulator.With simulation transparency we mean that network simulation is completely hidden from the protocols being executed/tested with the simulator.In PARSEC’s programming model, protocols are implemented in monolithic modules called entities,thus allowing only for vertical protocol composition(i.e.of protocol layers).The primitives of PARSEC are in-suf?cient for de?ning abstractions such as messages,migration and behavior patterns,and protocol abstractions.Instead they have to be explicitly programmed by the GloMoSim user.
Unlike other approaches,in M OBI CS we used the same programming language (Java)for the simulation engine and for the programming of the network elements
and the protocols,which also facilitates the distributed implementation of the simula-tor.Moreover,M OBI CS provides a uniform interface both for the deterministic and the stochastic simulation mode.Although the simulation level(the engine)works dif-ferently for each mode,the simulation mode can be switched without any change in the other layers of M OBI CS.ns and GloMoSim do not offer a mode for protocol testing,similar to M OBI CS’deterministic mode.There is still an approach called STRESS[Helmy and Estrin,1998]for generation of tests for critical execution scenarios, using with ns.However,this approach also requires the formal speci?cation of a protocol and it is usually not suf?ciently generic to be applied to a wide range of protocols.
The majority of network simulators also do not provide support for programming different mobility models,by which the user keeps tied to a single simulation model that may not be appropriate for testing some classes for distributed protocols.M OBI CS, on the other hand,provides its user with means for programming its own mobility and connectivity models,so that a user can model the behavior of the mobile network at the same level of abstraction as the protocol being prototyped.
7.Final Remarks
M OBI CS has been successfully used for teaching and research purposes since2000.Sev-eral mobile computing protocols have been simulated using M OBI CS such as mobile mul-ticasting,mobile IP,QoS management,consensus,replication and cache management.
Its main advantages are the?exibility for de?ning customized simulation mod-els that are compatible with the level of abstraction of the protocol to be tested,and the simulation transparency which allows the user to switch between a deterministic and a stochastic simulation without affecting the distributed protocols being prototyped.Some additional tools have been developed,allowing simulation of ad hoc networks and facili-tating the M OBI CS’use.
References
Acharya,A.and Badrinath,B.R.(1993).Delivering multicast messages in networks with mobile hosts.In13th International Conference on Distributed Computing Systems, pages292–299,Pittsburgh,US.
Alagar,S.,Rajagopalan,R.,and Venkatesan,S.(1995).Tolerating mobile support station failures.Proc.Int’l Conf.Fault-Tolerant Systems.
Alagar,S.and Venkatesan,S.(1994).Causally ordered message delivery in mobile sys-tems.In IEEE Workshop on Mobile Computing Systems and Applications,Santa Cruz, CA,US.
Badache,N.,Hur?n,M.,and Macedo,R.(1999).Solving the consensus problem in
a mobile environment.Performance,Computing and Communications Conference,
IPCCC’99,pages29–35.
Badrinath,B.R.,Bakre,A.,Imielinski,T.,and Marantz,R.(1993).Handling mobile clients:A case for indirect interaction.In Fourth Workshop on Workstation Operating System,pages91–97,Napa,US.
Bajaj,S.,Breslau,L.,Estrin,D.,Fall,K.,Floyd,S.,Haldar,P.,Handley,M.,Helmy,A., Heidemann,J.,Huang,P.,Kumar,S.,McCanne,S.,Rejaie,R.,Sharma,P.,Varadhan, K.,Xu,Y.,Yu,H.,and Zappala,D.(1999).Improving simulation for network research.
Technical Report99-702b,University of Southern California.revised September1999, to appear in IEEE Computer.
da Rocha,R.C.A.(2001).Uma arquitetura para simulac??a o?ex′?vel de protocolos para computac??a o m′o vel.Master’s thesis,Instituto de Matem′a tica e Estat′?stica,Universidade de S?a o Paulo-USP,S?a o Paulo,SP.(in portuguese).
da Rocha,R.C.A.and Endler,M.(2001).MobiCS:An environment for prototyping and simulating distributed protocols for mobile networks.In3rd.IEEE International Conference in Mobile and Wireless Communication Networks(MWCN′2001),pages 44–51,Recife,Brazil.
da Rocha,R.C.A.and Endler,M.(2005)https://www.sodocs.net/doc/d315583005.html,p.br/～mobics.
Home page.
dos Santos Lima,L.,Gomes,A.T.A.,Colcher,S.,and Soares,L.F.G.(2003).Um framework para provis?a o de QoS em redes m′o veis sem?o.In XXI Simp′o sio Brasileiro de Redes de Computadores.
Endler,M.(1999).A protocol for atomic multicast among mobile hosts.In3rd Inter-national Workshop on Discrete Algorithms and Methods for Mobile Computing and Communications(DIAL M’99),pages56–63,Seattle,Washington,USA.ACM SIG-MOBILE.
Endler,M.,da Silva,D.M.,and Okuda,K.(2000).RDP:A result delivery protocol for mobile computing.In Proc.of the Int.Workshop on Wireless Networks and Mobile Computing(WNMC)at the20th Int.Conference on Distributed Computing Systems (ICDCS),Taiwan,R.O.C.IEEE.
Estrin,D.,Handley,M.,Heidemann,J.,McCanne,S.,Xu,Y.,and Yu,H.(2000).Network visualization with nam,the VINT network animator.IEEE Computer,pages63–68. Helmy,A.and Estrin,D.(1998).Simulation-based‘STRESS’testing case study:A mul-ticast routing protocol.In Sixth International Symposium on Modeling,Analysis and Simulation of Computer and Telecommunication Systems(MASCOTS’98),Montreal, Canada.
Maia,R.,Sacramento,V.,and Endler,M.(2003).An′a lise,simulac??a o e correc??o es do protocolo mma para multicast em redes m′o veis estruturadas.In5o.Workshop de Comunicac??a o sem Fio e Computac??a o M′o vel(WCSF2003).
Mele,A.(2002).Um framework para simulac??a o de redes m′o veis ad hoc.Master’s thesis, PUC-Rio,Rio de Janeiro,Brazil.
Ribeiro,M.and M.Endler(2003).Comparing two reliable multicast protocols for mobile computing.Journal of the Brazilian Computer Society,8(3):17–39.
Suh,Y.-J.,Shin,H.-S.,and Kwon,D.-H.(2001).An ef?cient multicast routing protocol in wireless mobile networks.Wireless Networks,7(5):443–453.
Zeng,X.,Bagrodia,R.,and Gerla,M.(1998).GloMoSim:A library for parallel simula-tion of large-scale wireless networks.In Proceedings of the12th Workshop on Parallel and Distributed Simulation(PADS-98),pages154–161,Los Alamitos.IEEE Computer Society.
The way常见用法
The way 的用法 Ⅰ常见用法： 1)the way+ that 2)the way + in which（最为正式的用法） 3)the way + 省略（最为自然的用法） 举例：I like the way in which he talks. I like the way that he talks. I like the way he talks. Ⅱ习惯用法： 在当代美国英语中，the way用作为副词的对格，“the way+ 从句”实际上相当于一个状语从句来修饰整个句子。 1)The way =as I am talking to you just the way I’d talk to my own child. He did not do it the way his friends did. Most fruits are naturally sweet and we can eat them just the way they are—all we have to do is to clean and peel them. 2）The way= according to the way/ judging from the way The way you answer the question, you are an excellent student. The way most people look at you, you’d think trash man is a monster. 3）The way =how/ how much No one can imagine the way he missed her. 4）The way =because
The way的用法及其含义(二)
The way的用法及其含义（二） 二、the way在句中的语法作用 the way在句中可以作主语、宾语或表语： 1.作主语 The way you are doing it is completely crazy.你这个干法简直发疯。 The way she puts on that accent really irritates me. 她故意操那种口音的样子实在令我恼火。The way she behaved towards him was utterly ruthless. 她对待他真是无情至极。 Words are important, but the way a person stands, folds his or her arms or moves his or her hands can also give us information about his or her feelings. 言语固然重要,但人的站姿,抱臂的方式和手势也回告诉我们他(她)的情感。 2.作宾语 I hate the way she stared at me.我讨厌她盯我看的样子。 We like the way that her hair hangs down.我们喜欢她的头发笔直地垂下来。 You could tell she was foreign by the way she was dressed. 从她的穿著就可以看出她是外国人。 She could not hide her amusement at the way he was dancing. 她见他跳舞的姿势，忍俊不禁。 3.作表语 This is the way the accident happened.这就是事故如何发生的。 Believe it or not, that's the way it is. 信不信由你, 反正事情就是这样。 That's the way I look at it, too. 我也是这么想。 That was the way minority nationalities were treated in old China. 那就是少数民族在旧中
(完整版)the的用法
定冠词the的用法： 定冠词the与指示代词this ,that同源,有“那(这)个”的意思,但较弱,可以和一个名词连用,来表示某个或某些特定的人或东西. (1)特指双方都明白的人或物 Take the medicine.把药吃了. (2)上文提到过的人或事 He bought a house.他买了幢房子. I've been to the house.我去过那幢房子. (3)指世界上独一无二的事物 the sun ,the sky ,the moon, the earth (4)单数名词连用表示一类事物 the dollar 美元 the fox 狐狸 或与形容词或分词连用,表示一类人 the rich 富人 the living 生者 (5)用在序数词和形容词最高级,及形容词等前面 Where do you live?你住在哪? I live on the second floor.我住在二楼. That's the very thing I've been looking for.那正是我要找的东西. (6)与复数名词连用,指整个群体 They are the teachers of this school.(指全体教师) They are teachers of this school.(指部分教师) (7)表示所有,相当于物主代词,用在表示身体部位的名词前 She caught me by the arm.她抓住了我的手臂. (8)用在某些有普通名词构成的国家名称,机关团体,阶级等专有名词前 the People's Republic of China 中华人民共和国 the United States 美国 (9)用在表示乐器的名词前 She plays the piano.她会弹钢琴. (10)用在姓氏的复数名词之前,表示一家人 the Greens 格林一家人(或格林夫妇) (11)用在惯用语中 in the day, in the morning... the day before yesterday, the next morning... in the sky... in the dark... in the end... on the whole, by the way...
“the way+从句”结构的意义及用法
“tｈｅwａｙ+从句”结构的意义及用法 首先让我们来看下面这个句子: Ｒead the foｌloｗｉnｇpassagｅａnd talkａbout ｉt wi ｔh your classmaｔes．Try tｏｔeｌl whaｔyｏu thiｎk ｏf Tom aｎd ｏｆｔhe ｗay the chiｌｄrenｔrｅated ｈim. 在这个句子中，ｔhe waｙ是先行词,后面是省略了关系副词that或in whｉch的定语从句。 下面我们将叙述“the ｗaｙ+从句”结构的用法。 1.tｈe wａy之后，引导定语从句的关系词是tｈat而不是hoｗ,因此，<<现代英语惯用法词典＞＞中所给出的下面两个句子是错误的：Ｔhｉs is ｔｈeｗayｈowｉtｈａppened. This is the way how he ａlwａｙs treats me. 2．在正式语体中,thaｔ可被in which所代替;在非正式语体中，ｔhat则往往省略。由此我们得到theｗay后接定语从句时的三种模式：1) tｈe ｗaｙ＋ｔhａt-从句２）the way +ｉn whiｃh－从句3) the ｗay +从句 例如：Ｔｈe way(in whiｃh ，thａt) ｔhｅｓｅｃomｒade ｓloｏｋａｔｐrobｌems is wrong．这些同志看问题的方法
不对。 Ｔｈｅｗａy(that ,ｉn ｗhiｃh)yoｕ’ｒe doinｇit is comple ｔeｌy crａzy.你这么个干法,简直发疯。 Wｅａdmiｒｅd him for thｅｗay ｉｎｗhｉch he fａｃeｓdiｆficultieｓ． Waｌlａｃe ａｎd Ｄarwiｎｇreed ｏn the way ｉｎwhi ｃh ｄｉfｆｅrｅnt forms ｏf life had ｂegｕn.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 Thｉs is ｔｈe ｗaｙ（tｈａｔ) hｅdｉd it. I lｉkeｄｔhe waｙ(ｔhat) ｓｈeｏｒganized ｔhe ｍeetｉng． 3.theｗay(tｈat)有时可以与hｏw(作“如何”解）通用。例如： That’s tｈe ｗaｙ(tｈaｔ) shｅspoke. = Tｈat’s how shｅspoke.
way 用法
表示“方式”、“方法”，注意以下用法： 1.表示用某种方法或按某种方式，通常用介词in(此介词有时可省略)。如： Do it (in) your own way. 按你自己的方法做吧。 Please do not talk (in) that way. 请不要那样说。 2.表示做某事的方式或方法，其后可接不定式或of doing sth。 如： It’s the best way of studying [to study] English. 这是学习英语的最好方法。 There are different ways to do [of doing] it. 做这事有不同的办法。 3.其后通常可直接跟一个定语从句(不用任何引导词)，也可跟由that 或in which 引导的定语从句，但是其后的从句不能由how 来引导。如： 我不喜欢他说话的态度。 正：I don’t like the way he spoke. 正：I don’t like the way that he spoke. 正：I don’t like the way in which he spoke. 误：I don’t like the way how he spoke. 4.注意以下各句the way 的用法： That’s the way (=how) he spoke. 那就是他说话的方式。 Nobody else loves you the way(=as) I do. 没有人像我这样爱你。 The way (=According as) you are studying now, you won’tmake much progress. 根据你现在学习情况来看，你不会有多大的进步。 2007年陕西省高考英语中有这样一道单项填空题： ——I think he is taking an active part insocial work. ——I agree with you_____. A、in a way B、on the way C、by the way D、in the way 此题答案选A。要想弄清为什么选A，而不选其他几项，则要弄清选项中含way的四个短语的不同意义和用法，下面我们就对此作一归纳和小结。 一、in a way的用法 表示：在一定程度上，从某方面说。如： In a way he was right.在某种程度上他是对的。注：in a way也可说成in one way。 二、on the way的用法 1、表示：即将来(去)，就要来(去)。如： Spring is on the way.春天快到了。 I'd better be on my way soon.我最好还是快点儿走。 Radio forecasts said a sixth-grade wind was on the way.无线电预报说将有六级大风。 2、表示：在路上，在行进中。如： He stopped for breakfast on the way.他中途停下吃早点。 We had some good laughs on the way.我们在路上好好笑了一阵子。 3、表示：(婴儿)尚未出生。如： She has two children with another one on the way.她有两个孩子，现在还怀着一个。 She's got five children，and another one is on the way.她已经有5个孩子了，另一个又快生了。 三、by the way的用法
The way的用法及其含义(一)
The way的用法及其含义（一） 有这样一个句子：In 1770 the room was completed the way she wanted. 1770年，这间琥珀屋按照她的要求完成了。 the way在句中的语法作用是什么？其意义如何？在阅读时，学生经常会碰到一些含有the way 的句子，如：No one knows the way he invented the machine. He did not do the experiment the way his teacher told him.等等。他们对the way 的用法和含义比较模糊。在这几个句子中，the way之后的部分都是定语从句。第一句的意思是，“没人知道他是怎样发明这台机器的。”the way的意思相当于how；第二句的意思是，“他没有按照老师说的那样做实验。”the way 的意思相当于as。在In 1770 the room was completed the way she wanted.这句话中，the way也是as的含义。随着现代英语的发展，the way的用法已越来越普遍了。下面，我们从the way的语法作用和意义等方面做一考查和分析： 一、the way作先行词，后接定语从句 以下3种表达都是正确的。例如：“我喜欢她笑的样子。” 1. the way+ in which +从句 I like the way in which she smiles. 2. the way+ that +从句 I like the way that she smiles. 3. the way + 从句(省略了in which或that) I like the way she smiles. 又如：“火灾如何发生的，有好几种说法。” 1. There were several theories about the way in which the fire started. 2. There were several theories about the way that the fire started.
way 的用法
way 的用法 【语境展示】 1. Now I’ll show you how to do the experiment in a different way. 下面我来演示如何用一种不同的方法做这个实验。 2. The teacher had a strange way to make his classes lively and interesting. 这位老师有种奇怪的办法让他的课生动有趣。 3. Can you tell me the best way of working out this problem? 你能告诉我算出这道题的最好方法吗？ 4. I don’t know the way (that / in which) he helped her out. 我不知道他用什么方法帮助她摆脱困境的。 5. The way (that / which) he talked about to solve the problem was difficult to understand. 他所谈到的解决这个问题的方法难以理解。 6. I don’t like the way that / which is being widely used for saving water. 我不喜欢这种正在被广泛使用的节水方法。 7. They did not do it the way we do now. 他们以前的做法和我们现在不一样。 【归纳总结】 ●way作“方法，方式”讲时，如表示“以……方式”，前面常加介词in。如例1； ●way作“方法，方式”讲时，其后可接不定式to do sth.，也可接of doing sth. 作定语，表示做某事的方法。如例2，例3；
the-way-的用法讲解学习
t h e-w a y-的用法
The way 的用法 "the way+从句"结构在英语教科书中出现的频率较高, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或 in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 一.在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮.
way的用法总结大全
way的用法总结大全 way的用法你知道多少，今天给大家带来way的用法，希望能够帮助到大家，下面就和大家分享，来欣赏一下吧。 way的用法总结大全 way的意思 n. 道路,方法,方向,某方面 adv. 远远地，大大地 way用法 way可以用作名词 way的基本意思是“路,道,街,径”,一般用来指具体的“路,道路”,也可指通向某地的“方向”“路线”或做某事所采用的手段,即“方式,方法”。way还可指“习俗,作风”“距离”“附近,周围”“某方面”等。 way作“方法,方式,手段”解时,前面常加介词in。如果way前有this, that等限定词,介词可省略,但如果放在句首,介词则不可省略。
way作“方式,方法”解时,其后可接of v -ing或to- v 作定语,也可接定语从句,引导从句的关系代词或关系副词常可省略。 way用作名词的用法例句 I am on my way to the grocery store.我正在去杂货店的路上。 We lost the way in the dark.我们在黑夜中迷路了。 He asked me the way to London.他问我去伦敦的路。 way可以用作副词 way用作副词时意思是“远远地,大大地”,通常指在程度或距离上有一定的差距。 way back表示“很久以前”。 way用作副词的用法例句 It seems like Im always way too busy with work.我工作总是太忙了。 His ideas were way ahead of his time.他的思想远远超越了他那个时代。 She finished the race way ahead of the other runners.她第一个跑到终点,远远领先于其他选手。 way用法例句
the_way的用法大全教案资料
t h e_w a y的用法大全
The way 在the way+从句中, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或 in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 如果怕弄混淆，下面的可以不看了 另外，在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮. the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的
the way 的用法
The way 的用法 "the way+从句"结构在英语教科书中出现的频率较高, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 一.在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮.
the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的 the way =while/when(表示对比) 9)From that day on, they walked into the classroom carrying defeat on their shoulders the way other students carried textbooks under their arms. 从那天起,其他同学是夹着书本来上课,而他们却带着"失败"的思想负担来上课.
The way的用法及其含义(三)
The way的用法及其含义（三） 三、the way的语义 1. the way=as（像） Please do it the way I’ve told you.请按照我告诉你的那样做。 I'm talking to you just the way I'd talk to a boy of my own.我和你说话就像和自己孩子说话一样。 Plant need water the way they need sun light. 植物需要水就像它们需要阳光一样。 2. the way=how（怎样，多么） No one can imagine the way he misses her.没人能够想象出他是多么想念她！ I want to find out the way a volcano has formed.我想弄清楚火山是怎样形成的。 He was filled with anger at the way he had been treated.他因遭受如此待遇而怒火满腔。That’s the way she speaks.她就是那样讲话的。 3. the way=according as （根据） The way you answer the questions, you must be an excellent student.从你回答问题来看，你一定是名优秀的学生。 The way most people look at you, you'd think a trash man was a monster.从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物。 The way I look at it, it’s not what you do that matters so much.依我看，重要的并不是你做什么。 I might have been his son the way he talked.根据他说话的样子，好像我是他的儿子一样。One would think these men owned the earth the way they behave.他们这样行动，人家竟会以为他们是地球的主人。
way的用法
一．Way：“方式”、“方法” 1.表示用某种方法或按某种方式 Do it (in) your own way. Please do not talk (in) that way. 2.表示做某事的方式或方法 It’s the best way of studying [to study] English.。 There are different ways to do [of doing] it. 3.其后通常可直接跟一个定语从句(不用任何引导词)，也可跟由that 或in which 引导的定语从句 正：I don’t like the way he spoke. I don’t like the way that he spoke. I don’t like the way in which he spoke.误：I don’t like the way how he spoke. 4. the way 的从句 That’s the way (=how) he spoke. I know where you are from by the way you pronounce my name. That was the way minority nationalities were treated in old China. Nobody else loves you the way(=as) I do. He did not do it the way his friend did. 二．固定搭配 1. In a/one way：In a way he was right. 2. In the way /get in one’s way I'm afraid your car is in the way， If you are not going to help，at least don't get in the way. You'll have to move－you're in my way. 3. in no way Theory can in no way be separated from practice. 4. On the way (to……) Let’s wait a few moments. He is on the way Spring is on the way. Radio forecasts said a sixth-grade wind was on the way. She has two children with another one on the way. 5. By the way By the way，do you know where Mary lives? 6. By way of Learn English by way of watching US TV series. 8. under way 1. Elbow one’s way He elbowed his way to the front of the queue. 2. shoulder one’s way 3. feel one‘s way 摸索着向前走；We couldn’t see anything in the cave, so we had to feel our way out 4. fight/force one’s way 突破。。。而前进The surrounded soldiers fought their way out. 5.. push/thrust one‘s way（在人群中）挤出一条路He pushed his way through the crowd. 6. wind one’s way 蜿蜒前进 7. lead the way 带路，领路；示范 8. lose one‘s way 迷失方向 9. clear the way 排除障碍，开路迷路 10. make one’s way 前进，行进The team slowly made their way through the jungle.
the way的用法大全
在the way+从句中, the way 是先行词, 其后是定语从句.它有三种表达形式:1) the way+that 2)the way+ in which 3)the way + 从句(省略了that或in which),在通常情况下, 用in which 引导的定语从句最为正式,用that的次之,而省略了关系代词that 或in which 的, 反而显得更自然,最为常用.如下面三句话所示,其意义相同. I like the way in which he talks. I like the way that he talks. I like the way he talks. 如果怕弄混淆，下面的可以不看了 另外，在当代美国英语中,the way用作为副词的对格,"the way+从句"实际上相当于一个状语从句来修饰全句. the way=as 1)I'm talking to you just the way I'd talk to a boy of my own. 我和你说话就象和自己孩子说话一样. 2)He did not do it the way his friend did. 他没有象他朋友那样去做此事. 3)Most fruits are naturally sweet and we can eat them just the way they are ----all we have to do is clean or peel them . 大部分水果天然甜润,可以直接食用,我们只需要把他们清洗一下或去皮. the way=according to the way/judging from the way 4)The way you answer the qquestions, you must be an excellent student. 从你回答就知道,你是一个优秀的学生. 5)The way most people look at you, you'd think a trashman was a monster. 从大多数人看你的目光中,你就知道垃圾工在他们眼里是怪物. the way=how/how much 6)I know where you are from by the way you pronounce my name. 从你叫我名字的音调中,我知道你哪里人. 7)No one can imaine the way he misses her. 人们很想想象他是多么想念她. the way=because 8) No wonder that girls looks down upon me, the way you encourage her. 难怪那姑娘看不起我, 原来是你怂恿的 the way =while/when(表示对比) 9)From that day on, they walked into the classroom carrying defeat on their shoulders the way other students carried textbooks under their arms.
“the-way+从句”结构的意义及用法知识讲解
“the way+从句”结构的意义及用法 首先让我们来看下面这个句子： Read the following passage and talk about it with your classmates. Try to tell what you think of Tom and of the way the children treated him. 在这个句子中，the way是先行词，后面是省略了关系副词that 或in which的定语从句。 下面我们将叙述“the way+从句”结构的用法。 1．the way之后，引导定语从句的关系词是that而不是how,因此，<<现代英语惯用法词典>>中所给出的下面两个句子是错误的：This is the way how it happened. This is the way how he always treats me. 2. 在正式语体中，that可被in which所代替；在非正式语体中，that则往往省略。由此我们得到the way后接定语从句时的三种模式：1) the way +that-从句2) the way +in which-从句3) the way +从句 例如：The way(in which ,that) these comrades look at problems is wrong.这些同志看问题的方法不对。
The way(that ,in which)you’re doing it is completely crazy.你这么个干法，简直发疯。 We admired him for the way in which he faces difficulties. Wallace and Darwin greed on the way in which different forms of life had begun.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 This is the way (that) he did it. I liked the way (that) she organized the meeting. 3.the way(that)有时可以与how(作“如何”解)通用。例如： That’s the way (that) she spoke. = That’s how she spoke. I should like to know the way/how you learned to master the fundamental technique within so short a time. 4．the way的其它用法：以上我们讲的都是用作先行词的the way，下面我们将叙述它的一些用法。
定冠词the的12种用法
定冠词the的12种用法 定冠词the 的12 种用法，全知道?快来一起学习吧。下面就和大家分享，来欣赏一下吧。 定冠词the 的12 种用法，全知道? 定冠词the用在各种名词前面，目的是对这个名词做个记号，表示它的特指属性。所以在词汇表中，定冠词the 的词义是“这个，那个，这些，那些”，可见，the 即可以放在可数名词前，也可以修饰不可数名词，the 后面的名词可以是单数，也可以是复数。 定冠词的基本用法： (1) 表示对某人、某物进行特指，所谓的特指就是“不是别的，就是那个!”如： The girl with a red cap is Susan. 戴了个红帽子的女孩是苏珊。 (2) 一旦用到the，表示谈话的俩人都知道说的谁、说的啥。如：
The dog is sick. 狗狗病了。(双方都知道是哪一只狗) (3) 前面提到过的，后文又提到。如： There is a cat in the tree.Thecat is black. 树上有一只猫，猫是黑色的。 (4) 表示世界上唯一的事物。如： The Great Wall is a wonder.万里长城是个奇迹。(5) 方位名词前。如： thenorth of the Yangtze River 长江以北地区 (6) 在序数词和形容词最高级的前面。如： Who is the first?谁第一个? Sam is the tallest.山姆最高。 但是不能认为，最高级前必须加the，如： My best friend. 我最好的朋友。 (7) 在乐器前。如： play the flute 吹笛子
Way的用法
Way用法 A:I think you should phone Jenny and say sorry to her. B:_______. It was her fault. A. No way B. Not possible C. No chance D. Not at all 说明：正确答案是A. No way，意思是“别想！没门！决不！” 我认为你应该打电话给珍妮并向她道歉。 没门！这是她的错。 再看两个关于no way的例句： （1）Give up our tea break? NO way! 让我们放弃喝茶的休息时间？没门儿！ （2）No way will I go on working for that boss. 我决不再给那个老板干了。 way一词含义丰富，由它构成的短语用法也很灵活。为了便于同学们掌握和用好它，现结合实例将其用法归纳如下： 一、way的含义 1. 路线
He asked me the way to London. 他问我去伦敦的路。 We had to pick our way along the muddy track. 我们不得不在泥泞的小道上择路而行。 2. （沿某）方向 Look this way, please. 请往这边看。 Kindly step this way, ladies and gentlemen. 女士们、先生们，请这边走。 Look both ways before crossing the road. 过马路前向两边看一看。 Make sure that the sign is right way up. 一定要把符号的上下弄对。 3. 道、路、街，常用以构成复合词 a highway（公路），a waterway（水路），a railway（铁路），wayside（路边）
way与time的特殊用法
way/time的特殊用法 1、当先行词是way意思为”方式.方法”的时候,引导定语从句的关系词有下列3种形式： Way在从句中做宾语 The way that / which he explained to us is quite simple. Way在从句中做状语 The way t hat /in which he explained the sentence to us is quite simple. 2、当先行词是time时,若time表示次数时,应用关系代词that引导定语从句,that可以省略; 若time表示”一段时间”讲时,应用关系副词when或介词at/during + which引导定语从句 1.Is this factory _______ we visited last year? 2.Is this the factory-------we visited last year? A. where B in which C the one D which 3. This is the last time _________ I shall give you a lesson. A. when B that C which D in which 4.I don’t like the way ________ you laugh at her. A . that B on which C which D as 5.He didn’t understand the wa y ________ I worked out the problem. A which B in which C where D what 6.I could hardly remember how many times----I’ve failed. A that B which C in which D when 7.This is the second time--------the president has visited the country. A which B where C that D in which 8.This was at a time------there were no televisions, no computers or radios. A what B when C which D that