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Privacy is Linking Permission to Purpose

Privacy is Linking Permission to Purpose

Fabio Massacci1and Nicola Zannone1

Department of Information and Communication Technology

University of Trento-Italy

{massacci,zannone}at dit.unitn.it

Abstract.The last years have seen a peak in privacy related research.

The focus has been mostly on how to protect the individual from being

tracked,with plenty of anonymizing solutions.

We advocate another model that is closer to the“physical”world:we

consider our privacy respected when our personal data is used for the

purpose for which we gave it in the?rst place.

Essentially,in any distributed authorization protocol,credentials should

mention their purpose beside their powers.For this information to be

meaningful we should link it to the functional requirements of the original

application.

We sketch how one can modify a requirement engineering methodology to

incorporate security concerns so that we explicitly trace back the high-

level goals for which a functionality has been delegated by a(human

or software)agent to another one.Then one could be directly derive

purpose-based trust management solutions from the requirements.

1Privacy Protection and Cleaning Ladies

Consumer privacy1is a growing concern in the marketplace.While the concerns are most prominent for e-commerce,the privacy concerns for traditional trans-actions are increasing as well.Some enterprises are aware of these problems and of the market share they might loose if they do not implement proper privacy practices.As a consequence enterprises publish privacy statements that promise fair information practices2.

There are a number of risks to an enterprise if it does not manage its per-sonally identi?able information correctly.Recently,many countries have promul-gated a new privacy legislation.Most of these laws incorporate rules governing This work has been partially funded by the IST programme of the EU Commission, FET under the IST-2001-37004WASP project and by the FIRB programme of MIUR under the RBNE0195K5ASTRO Project.We would like to thank P.Giorgini,M.

Pistore,and J.Mylopoulos for many useful discussions on Tropos.

1Privacy is the right of individuals to determine for themselves when,how,and to what extent information about them is communicated to others(Alan Westin).

2The OECD de?ned a set of privacy principles in1980.The document OECD Guide-lines on the Protection of Privacy and Transborder Flows of Personal Data is con-sidered to contain the core requirements for managing privacy today.

collection,use,store and distribution of personally identi?able information.It is up to an organization to ensure that data processing operations respect any legislative requirements.If an enterprise breaches trust,that is,it uses data for other purposes,then it can be sued.Further,business relationships are built on https://www.wendangku.net/doc/f72521977.html,anizations that demonstrate good privacy practices can build trust. Organizations with no privacy practices will turn away customers.

The last years have seen a substantial increase in privacy-related security research3:we have a number of dedicated workshops(e.g.PET,WPES),a num-ber of European and US projects and standard initiatives such as P3P.In the realm of cryptography the work on anonymizing networks and transactions has a long history since Chaum’s?rst proposals.One could even say that trust ne-gotiation’s birth itself[11]was spurred by privacy concerns of non-disclosure of sensitive credentials to unknown strangers.

However,the current set of solutions is slight unsatisfactory:we must either struggle on keeping privacy by a complex cryptographic infrastructure or be involved in complex protocols for trust negotiation.

Not long ago,at a Cambridge seminar,Robert Morris,formerly from the US NSA,spoke about the cryptographic role of the cleaning ladies,inviting people to consider the actual perimeter of one’s secure systems.We would like to use the example with a slightly di?erent view.

Indeed,from the standpoint of access control and privacy protection,the problem of the cleaning ladies admits no solution.The cleaning lady must have access to the room and even when the room is not occupied to avoid disturbing people while at work.There is no way to prevent her from looking at the papers laying on the desk,even searching through them,doing any possible action on the unattended desktop and leaving unnoticed.

Yet,we do allow cleaning ladies and we are perfectly happy with many others similar problems.One possible explanation may be in the the actual economics of trust in cleaning ladies wrt the risk of privacy losses[12].However,we believe that the solutions lies in the implicit permission model that we use in the physical world,but so far we have not implemented in trust management protocols.

So it is useful to consider how the legal profession de?nes the power of at-torney:with the general power of attorney the individual appointed attorney in fact is vested with unlimited powers for an inde?nite amount of time(unless otherwise explicitly speci?ed).The validity of this of power of attorney ceases only with a speci?c written revocation or with the death of the person that has granted it.This is the way we used as delegation of“identity”works in trust management systems4,and is also the idea behind usage of data by systems. Once the system has the data,it will be used.We can read privacy policies to guarantee that the data will not be misused but we have no way to know that this policy will actually be enforced by the system.Privacy polices are added after the system has been built.

3A comprehensive and updated literature survey can be found at https://www.wendangku.net/doc/f72521977.html,/anonbib/date.html.

4This is the A speaks for B paradigm of SDSI/SPKI[6]

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What is interesting for our purposes is the special power of attorney:the individual appointed attorney is vested solely with the power needed to carry out a speci?c a?air(i.e.the sale or purchase of a real estate or a car).Therefore, in the formal contract it is necessary to indicate exactly the particular power that the principal intends to give to his attorney.Actual documents state quite explicitly the powers but also the goal for with these powers have been delegated. If I have to sell a house I may do all that I deem?t,but everything got tagged by that purpose and if my action is clearly not necessary I might be asked to pay for incurred losses.This is the missing important twist:in our trust management and data processing systems we have implemented only the description of powers but not the purpose.

Back to the cleaning lady,in giving her the door’s key we have stipulated(or better our administration has)a contract that she has the permission of entering the room with the goal of cleaning it.Any other action would constitute breach of contract and would result in fees or contract resolution.

That’s our claim:we feel that our privacy is protected because the permission we are granting is linked to a purpose.Notice that the the purpose is not at all security related but rather a functional goal of the system.

There are already solutions to link permissions to purpose in databases,such as the work on Hippocratic databases[1],but we found no proposals for other methods for data and credential management in distributed trust management or trust negotiation.However,it is not di?cult to add yet another?eld to an X.509/SPKI/etc.certi?cate format.

The intriguing issue is how can we link the permission in a credential doled out by the security sub-system to the actual functional goals of the entire system?

The strategy that we envisage is the following:

–?nd a“traditional”requirements methodology in which functional goals can be made explicit;

–enhance the methodology with security-related features such as trust and delegation that are linked to the explicit goals;

–each time a delegation of permission must be foreseen by the system designer, she can trace back on the design the goals and make that explicit.

2Related Work

The last years have seen an increasing awareness that privacy plays a key role in system development and deployment.This awareness has been matched by a number of research proposals on privacy.Next,we present some of those adopting solution to link permissions to purpose.

Platform for Privacy Preferences5(P3P),developed by the World Wide Web Consortium(W3C),is an emerging standard whose goal is to enable users to gain more control over the use of their personally identi?able information(PII) on web sites they visit.P3P enables web sites to express their privacy practices 5https://www.wendangku.net/doc/f72521977.html,/TR/P3P/

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in a standard format that can be retrieved automatically and interpreted easily by user.P3P provides a way for a web site to encode its data-collection and data-use practices in a machine-readable XML format known as a P3P policy.

P3P policies provide contact information for the legal entity making the rep-resentation of privacy practices in a policy,enumerate the types of data or data elements collected,and explain how the data will be used.In addition,policies identify the data recipients,and make a variety of other disclosures including information about dispute resolution,and the address of a site’s human-readable privacy policy.In other words,P3P policies represent the practices of the site. Each P3P policy is applied to speci?c web resources listed in a policy reference ?le.By placing one or more P3P policies on a web site,a company does not make any statements about the privacy practices associated with other web re-sources not mentioned in their policy reference?le,with other online activities that do not involve data collected on web sites covered by their P3P policy,or with o?ine activities that do not involve data collected on web sites covered by their P3P policy.

Agrawal et al.[2]propose an server-centric architecture for P3P.The P3P protocol has two parts:Privacy Policies,an XML format in which a web site can encode its data-collection and data-use practices,and Privacy Preferences, an XML format for specifying client privacy preferences.In the server-centric architecture,a web site?rst installs its privacy policy in a data system.Then database querying is used for maching a user privacy preference against privacy policies.Finally,web site sent result of matching preference against policy to the client,and the client requests web page if policy conforms to his/her preference. This approach is di?erent from ours,because it does not explain the permission purpose that is implicit in privacy policies of the web site.Further,the client have to choose without knowing all the available policies of the web site.For example, there are web sites that provide services only if a client agrees a certain policy, but they show multi-policies without specifying which policy is su?cient to get the service.In this case the client could grant more permissions than necessary.

In summary,as a?rst step towards managing privacy,organizations publish privacy promises.The P3P statements can be used by a P3P client(e.g.the Internet Explorer6web browser)to notify the user automatically whether the privacy policy of the enterprise matches that con?gured by the user.However, this is not su?cient to guarantee the enforcement of the promises that enter-prises have made,and has resulted in privacy violations,even from well meaning companies.In fact,P3P is an language for expressing privacy promises on web sites,but it cannot be used to enforce them within an enterprise.

The Enterprise Privacy Authorization Language6(EPAL),developed by IBM, enables an enterprise to formalize the exact privacy policy that shall be enforced within the enterprise.It formalizes the privacy promises into policies and asso-ciates a consented policy to each piece of collected data.This consented policy can then be used in access control decisions to enforce the privacy promises made.The EPAL policy language categorizes the data an enterprise holds and 6https://www.wendangku.net/doc/f72521977.html,/security/enterprise-privacy/epal/

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the rules which govern the usage of data of each category.An EPAL policy is essentially a set of privacy rules.A rule is a statement that includes a data user, an action,a data category,and a purpose.A rule may also contain conditions and obligations.

Next,we present an architecture for implementing privacy management based on EPAL.During submission of PII,the privacy management system(by sub-mission monitors)will create the submission records.This data is a permanent record of when PII was submitted,what privacy policy version was in place at that time,and what the users preferences https://www.wendangku.net/doc/f72521977.html,ter,when PII is to be accessed, the privacy management enforcement monitors ensure that only data accesses are allowed that conform to the privacy policy.They also create access records that record which user accessed the data and for what purpose.The combination of submission and enforcement monitors allow the enterprise to prove that it is a good data keeper and gives the enterprise some assurance that it is enforcing its stated privacy policy.

EPAL aims at formalizing enterprise-internal privacy policies.This requires a vocabulary that formalizes the privacy relevant aspects of an enterprise.It also includes a hierarchy of purposes for which the enterprise collects data.On the other hand,P3P aims at formalizing privacy statements that are published by an enterprise.The goal is to de?ne a machine-readable equivalent for the human readable privacy promises that are published as a privacy statement on a web page.Unlike EPAL,P3P de?nes a global terminology that can be used to describe the privacy promises for any enterprise.Although P3P is well suited for expressing policies,it is not as suitable for expressing an internal enforceable privacy policy.EPAL on the other hand is designed speci?cally to express an internal privacy policy that can be enforced by an enterprise privacy management system.IBM is currently investigating how to project a P3P policy from EPAL.

There are already solutions to link permissions to purpose in databases.Fol-lowing this approach,Agrawal et al.show that the database community has the opportunity to play a central role re-designing databases to include responsabil-ity for the privacy of data as a fundamental tenet.Inspired by the Hippocratic Oath,they propose to call Hippocratic databases[1]those databases that have privacy as a central concern.Agrawal et al.propose the key principles for such Hippocratic database systems,distilled from the principles behind current pri-vacy legislations and guidelines.Particularly,such principles highlight that the purposes for which PII has been collected shall be stored with that information in the databases,that the purposes associated with PII shall have consent of the owner of data,and that the PII collected,used,and stored shall be limited to the minimum necessary for accomplishing the speci?ed purposes.

Hippocratic databases can be useful to add enforcement dimension to P3P. As we have seen above,a P3P policy essentially describes the purpose of the collection of information along with the intended recipients.The policy descrip-tion uses data tags to specify the data items for which the policy is being stated. P3P’s concepts of purpose and retention can be mapped directly into analogous concepts in Hippocratic databases.Thus,from a P3P policy it is possible to

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generate the corresponding data structures(i.e.,a privacy-policies table)in the Hippocratic database system.

What is still missing in these proposals is capturing the high-level privacy requirements,without getting suddenly bogged down into security solutions or cryptographic algorithms.If we look at the requirements re?nement process of many proposals,we?nd out that at certain stage a leap is made:we have a system with no privacy features consisting of high-level functionalities,and the next re?nement shows encryption,access control and authentication.The modeling process should instead makes it clear why encryption,access control and authentication are necessary.This work is a step in this direction closing the gap between the functional and privacy requirements and the trust management architecture that is now emerging as the standard way to implement security in distributed systems.

3Goal-Oriented Security Engineering

The basic building block is a“traditional”requirements methodology in which functional goals are explicit:the Tropos framework.It is an agent-based software engineering methodology[3,4]that strives to model both the organizational environment of a system and the system itself.It uses the concepts of actor, goal,plan,resource and social dependency for de?ning obligations of actors (dependees)to other actors(dependers).Actors have strategic goals within the system or the organization and represent(social)agents(organizational,human or software),roles etc.A goal represents some strategic interest of an actor.A plan represents a way of doing something(in particular,a plan can be executed to satisfy a goal).A resource represents a physical or an informational entity. Finally,a dependency between two actors indicates that one actor depends on another to accomplish a goal,execute a plan,or deliver a resource.In the sequel, when the distinction between goal,plan or resource is not essential we use the term service to denote any of them.

Tropos has been designed with cooperative information systems in mind and therefore it is already equipped with a methodology for reasoning about func-tional delegation of goals.Goal delegation arises quite naturally among coop-erative,rational actors:every actor pursues its own goals,goal partitioning is a standard divide-and-conqueror strategy,and usually in a collaborative envi-ronment there are enough hierarchy and trust relationships,so that an actor is likely to?nd some other one to delegate a subgoal.When considered from an actor coordination perspective,goal delegation has two main facets:

–Delegation of commitment.This means that the delegatee should embrace the intentions of the delegater,trying to ful?ll the goal as it was one of its own.From delegater point of view,this requires a kind of trust:the delegater has to believe that the delegatee is trustworthy and will honestly try to achieve the goal.

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–Delegation of strategy.Delegating a declarative goal instead of an operational plan means that the delegater is interested only in the resulting outcome and not in a speci?c way the delegatee ful?ll it.

The incorporation of security features in Tropos is not trivial and is discussed in another paper[7].It is essentially based on the following intuition:in the dependency relationship it is implicitly assumed that if I delegate the execution of a service to somebody else I’m implicitly also the owner of this service.This implicit assumption is no longer true when also security requirements and not just functional requirements are part of the target.

In this modeling framework,four relationships(beside the old functional dependency)can be singled out:

trust(among two agents and a service),so that A trust B on a certain goal G; delegation(among two agents and a service),whenever A explicitly delegates to B a goal,or the permission to execute a plan or access a resource;

o?er(between an agent and a service),so that A can o?er to other agents the possibility of ful?lling a goal,executing a plan or delivering a resource; ownership(between an agent and a service),whenever an agent is the legite-mate owner of a goal,plan or resource.

Note the di?erence between trust and delegation.Delegation marks a formal passage in the requirements modeling:a TM certi?cate will have to be eventually issued for the delegatee when implementing the system.In contrast,trust marks simply a social relationship that is not formalized by a“contract”(such as digital credential).There might be cases(e.g.because it is impractical or too costly), where we might be happy with a“social”protection,and other cases in which security is essential.In this model,there is no relationship between trust and delegation

The requirements engineering methodology proposed in[7]speci?es how to derive the trust management system(aka the delegation relationship)from the general requirement:

1.design a trust model among the actors of the systems;

2.identify who owns goals,plans,or resources and who is able to ful?ll goals,

execute plans or deliver resources;

3.de?ne functional dependencies(functional delegations)of goals among agents

building a functional model;

4.de?ne a trust management implementation(e.g.based on the Delegation

logics by Li et al.[8–10])in which the delegation of permissions is de?ned. In[7]it is also shown how one can use Datalog and the DLV system[5]to model check the correctness of the implementation wrt the previous two model or the consistency of the functional model with the trust model.

However,in[7]there is no notion of Goal-linked permission,though the framework have all necessary machinery,simply because all considered target trust management systems for the last phase have no notion of Goal-linked permission.

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4A basic e-Health case study

Here we show a very basic case study,based on a modelling an e-Health service. We consider the following actors:

–Patient,that depends on the hospital for receiving appropriate health care;–Hospital,that provides medical treatment and depends on the patients for having their personal information.

–Clinician,physician of the hospital that provides medical health advice and, whenever needed,provide accurate medical treatment;

–Health Care Authority(HCA)that control and guarantee the fair resources allocation and a good quality of the delivered services.

–Medical Information System,that,according the current privacy legislation, can share the patients medical data if and only if consent is obtained.The Medical Information System manages patients information,including infor-mation about the medical treatments they have received.

In order to provide rapid and accurate medical treatments,clinicians need a fast access to their patient’medical data.Similarly,HCA needs a fast and reliable access to the data in order to allocate e?ectively the available resources, and guaranteeing then that each patient can receive a good quality of medical care.Furthermore,HCA wants to be sure that the system cannot be defrauded in any way and that clinicians and patients behave within the limits of their roles.To the other hand,the obvious right of the patient to restrict access on his/her medical data and moreover,to be able to use some safeguards on the privacy of these data,should be taken into serious consideration.The patient’s consent must be requested,and he must be noti?ed when its data is shared.

Figure1and Figure2show respectively the trust model and the functional model.Actors are represented as circles,goals by ovals,plans by polygons and relationships by labelled arrows.The ownership relationship has an edge labelled by O.We use trust(T)to model the basic trust relationship between agents and permission(P)to model the actual transfer of rights in some form(e.g.a digital certi?cate,a signed paper,etc.).This is the delegation of permission.The plain D is used for dependency,that is the functional delegation.

In the trust model Patient trusts HCA and Clinician for his personal informa-tion,and HCA trusts Hospital for it.Further,Hospital trusts HCA for checking equity resource distribution.Clinician trusts Hospital for medical treatment and for requesting speci?c professional consulting,and Hospital trusts Clinician for providing such consulting and for patient personal information.We also con-sider the trust relationship between Hospital and Medical System Information for patient personal information.Notice on top of Fig.1that there is a trust relationship between two actors(HCA and Hospital)on a resource that is owned by neither of them.

In the functional model,Patient depends on Hospital for medical treatments, and in turn,Hospital depends on Clinician for such treatments.To provide accu-rate medical treatment,Clinician can request speci?c professional consultancy

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Fig.1.Health Care System trust model

to Hospital that depends on other Clinicians for this consultancy.Hospital dele-gates the goal of checking equity resource distribution to Health Care Authority. Clinician and Health Care Authority need patient personal information to ful?ll their service.Thus,Patient delegates them his personal information.Further, Health Care Authority re-delegates these data to Hospital.

Notice that it is not necessary for the owner of the data to delegate the data directly to the entity that will use the service.For example here the patient can delegate the usage of his personal information to the HCA with a certain depth so that HCA can eventually re-delegate it to the actual service provider.

This trust-functional-TM implementation process is not static:requirements can be re?ned,new actors can be introduced,delegations can be split or passed further down the line,etc.To clarify re?nement analysis in Tropos,one can use rationale diagrams that explain relationships among actors and decompose high level goals into subgoals as in Figure3.This makes even more explicit how permissions should be linked to high-level goals.

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Fig.3.Rationale Diagram

5Linking Permission to Purpose

Now we have all the necessary machinery to ensure the patient that his privacy will not be violated.It is of course possible to specify in details all possible delegations in this model.Indeed,this is what has been done in the paper[7]. The formal analysis carried out there has shown that this process is extremely error prone and even the expansion of delegation certi?cates to include blacklists may not be su?cient to rule out certain delegation paths.

In this setting is may seem unnecessary to link permission to goals:after all, few lines above we have just de?ned delegation as a ternary relations between a pair of agents and a service(which might be a goal).This is not what we meant by tagging permissions to purpose.The three-place delegation is a delegation of a permission.Simply the framework makes it possible to delegate something better than a simple action such as exec,or a resource.So I can delegate a plan (which is just a big composite?xed action)or a goal in which case I simply delegate all possible plans that can ful?ll the goal.If we go back to the special power of attorney we have only mentioned the how but not the why.

The direct base case for linking permission to purpose is the following:

1.the owner and the depender of a service are the same actor

2.the service is a primary service of the depender and has not been obtained

by re?nement from other goals7.

7In the Tropos methodology only goals can be re?ned.We stick to this line here, though from a security perspective also resources may be additionally re?ned for ?ne-grained access control.

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In this case the delegation of the service from the owner to the provider of the service is tagged by the service of the functional dependency of the owner.

In the reverse base case the owner and the dependee of the service coincides. Also in this case the credential should be tagged with the goal of the owner but it is worth noting that the emission of this credential is not trivial.Indeed,the owner of the service should have some reason to delegate a service besides a cooperative spirit.

Notice that this is not really the case in our e-health example.For example the Hospital do need the patient personal data(of which the patient is at the same time the owner and the dependee).However,in this case the patient personal data is obtained during the design process as a re?nement of the patient’s own goal of obtaining care which has been delegated to the hospital.In most practical cases this is the typical format:an high-level goal of agent A is delegated to agent B and after a suitable number of recursions and re?nements a subgoals is delegated from C back to A.This is typically providing information for actually ful?lling some other task necessary for the overall goal.

In the general case we have that

1.owner A,depender B,and dependee C of a service are all di?erent actors,

2.the service S is a derived service from another goal G d of the depender,

3.the service is also a derived service from a possibly di?erent goal G o of the

owner.

The simplest solution is to add the conjunction G d∧G o of the owner’s goal and the depender’s goal to the digital credential.There might be cases in which the designer may want di?erent schemes.

After the linkage between permission and purpose has been put in place,we can check that a delegation chain is also an appropriate delegation of purpose by checking that each goal along the delegation is a subgoal of the initial base case and each step is also appropriate.This can be easily done within the same datalog framework used in[7]

An interesting question is whether we should have also noted in the delegation credential the actual agent names to which the“purpose”-goals belonged.So far we could not?nd a situation in which such information is needed and cannot be reconstructed from the delegation chain.

6Conclusions?

In framework we have proposed,privacy is considered during the whole process of requirements analysis modeling trust and delegation relationships between the stackholders and the system-to-be.In this way,the framework we propose allows to capture privacy requirements at an organizational level,and hence,to help designers to model privacy concerns throughout the whole software development process.

In this paper we have discussed how a trust management(sub)system can accommodate the notion of purpose of a permission by linking it directly with

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the functional requirement of the overall information system.This makes possi-ble to capture the high-level privacy requirements without taking cryptographic algorithms or protocols for trust negotiation into considerations.

There are a number of open questions that we have not answered and that are worth discussing:

–which format can be used for goals in certi?cates?A string?eld costs nothing to include but in this way all possibilities that we have listed of linking goals to subgoals would be lost as only equality would be tested.So a semantic web solution may be used but this may be costly from a processing perspective.–are distributed implementations possible?and in particular can existing im-plementations of Trust Management systems be ported to this new frame-work(at least under the assumption that somebody has already magically derived the goal-oriented trust management implementation)?How e?ective and essential should purpose veri?cation in the credential chain be?

–how history should be presented in the purpose?One possible solution is no history at all,just mention the last delegation step;another solution could be let history be recovered by the chain of credentials so that one could?nally check if all credential have been gathered for the appropriate purpose.

–what kind of automatic support could be available for the automatic synthesis and validation of the trust management implementation.

–can we de?ne a similar process for the de?nition of Hippocratic databases? References

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英语语法的五种基本句型

教学目标: 1.让学生掌握英语学习中的五种基本句型; 2.学会分辨句子属于哪种句型; 3.懂得使用不同的句型造句; 教学重点与难点: 1.五种句型的分析与理解; 2.句型4(主+动+宾+补)与句型5(主+动+宾+宾)的掌握与比较; 教学方法: 1.ppt演示; 课堂练习: 一、下列的句子属于哪种类型 1. The sun rises 2. She is walking along the lake. 3. I like this book very much. 4. That man seems kind 5. He bought his sister a piano. 6. She kept us waiting for over three hours. 7. Let me give you a hand. 8. We tried to make her happy. 二、请说出五个句子,并说出属于哪种句型 家庭作业: 1.每个句型各举出3个句子 2.翻译句子

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常用口语: 1. I’m not myself!我烦透了! 2. Don’t bother me!别烦我! 3. Give me five more minutes, please. 再给我五分钟时间,好吗? 4. How did you sleep? 你睡的怎么样? 5. Don’t hog the bathroom! 别占着卫生间了! 6. Don’t hog the shower! 别占着浴室了! 7. Don’t hog my girlfriend! 别缠着我的女朋友了! 8. Get outta there! 快出来! 9. I will treat you. 我请客。 10. What are you in the mood for? 你想吃什么? 11. Who is gonna drive? / Who’s driving? 谁来开车? 12. You know what I mean? 你明白我的意思吗? 13. Could you run that by me again?

你能再说一遍吗? 14. So what you are trying to say is... 那么,你想说的是…… 15. Whadja do last night? 昨晚你干嘛去了? Whadja=What did you 16. Didja have a good time? 玩的开心吗? didja=did you 17. Where wouldja like to go tonight? 今晚你想上哪儿? Wouldja=Would you 18. I am running late. 我要迟到了。 19. I’ve gotta get outta here. 我得离开这儿了。 20. I’ve gotta catch the bus. 我要去赶公共汽车了。 21. gotta=got to wanna=want to gonna=going to 22. Yo—taxi! 嗨,出租车! 23. Where to ? (你)要去哪儿?

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preparetodosth.准备做某事 pretendtodosth.假装做某事 promisetodosth.答应做某事 refusetodosth.拒绝做某事 wanttodosth.想要做某事 wishtodosth.希望做某事 注:有些不及物动词后习惯上也接不定式,不接动名词:aimtodosth.打算做某事 failtodosth.未能做某事 longtodosth.渴望做某事 happentodosth.碰巧做某事 hesitatetodosth.犹豫做某事 struggletodosth.努力做某事 二、接不定式作宾补的36个常用动词 advisesb.todosth.建议某人做某事 allowsb.todosth.允许某人做某事 asksb.todosth.请(叫)某人做某事 bearsb.todosth.忍受某人做某事 begsb.todosth.请求某人做某事 causesb.todosth.导致某人做某事 commandsb.todosth.命令某人做某事 drivesb.todosth.驱使某人做某事 electsb.todosth.选举某人做某事

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初中英语语法五种基本句型

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2011三星笔试固定搭配必背句型 固定搭配必背句型 1. allow sb to do sth 允许某人去做某事(后接动词不定式) My father allowed me to go out for a walk after finishing my homework. 2. asked sb (not) to do sth 叫某人做事某事(叫某人不要去做某事) My father asked me to study hard. He asked me not to swim alone. be asked to do sth 被叫去做某事/被邀请去做某事 I was asked to have a dinner with them yesterday. 3. be afraid to do sth 害怕做某事 She is afraid to ask me questions. 4. be afaid of doing sth 害怕做某事 I am afraid of going out at night. 5. be afaid of sth 害怕某物 He is afraid of snakes. 6. be amazed to do sth 对做某事感到惊讶 He was amazed to meet the girl there. be amazed at sth 对某事感到惊讶 they were amazed at the news. 7. be busy doing/with sth 忙于做某事(常考) I was busy washing my car at that time. 那时候我正忙于清洗我的车子。 I am busy with my work. 8. be coming/going/leaving/fiying/moving/dying(某些位移动词用进行时态时表将来) the bus is coming/the dog is dying. 9. be excited to do sth 对做……感到兴奋 Jacky was excited to travel there by plane. be excited at sth Lily was excited at his words. be excited about doing sth he was excited about passing the exam without going overing books. 10. be frightened to do sth 害怕去做某事 Sam is frightened to ride a horse. 11. be glad/happy to do sth 高兴去做某事 she is happy to clean the blackboard with me. be pleased to do sth高兴做某事 she was pleased to help the old man yesterday. be pleased with sth 对某事感到高兴/满意 the teacher was pleased with my answer. 12. be interested in sth/doing sth 对某事感兴趣/对做某事感兴趣 she is interested in swimming in the river. My btother is interested in Chinese. 13. be/get ready for/to do sth Be ready for sth 为某事做好了准备 We are ready for the exam.

英语中的五种基本句型.

五种基本句型 句子由主语和谓语两大部分组成。主语结构比较单一,谓语结构则不然,不同类别的谓语动词导致不同的谓语结构,从而形成了不同的句型(Sentence Pattern)。换句话说,不同的句型是由不同类别的谓语动词所决定的,因此,句型又被称为动词句型(Verb Pattern)。语法家们对句型的分类不尽相同,一般认为,现代英语的基本句型主要有五种: 1.“主----系-----表”(SLP)句型: 在这种句型中,谓语动词是以be为主的连系动词(Linking Verb),后面跟主语补语(Subject Complement),如: These oranges have kept fresh. 这些桔子一直很新鲜。 Mary is a student / here /in the room. 玛丽是个学生/在这儿/在房间里。 有的语法家把be后面的副词(短语)或介词短语视为状语,从而形成了“主----动-----状”(SVA)这一在五种基本句型之外的句型(见上面最后一个例句)。 2.“主----动”(SV)句型: 在这种句型中,谓语动词为不及物动词(Intransitive Verb),谓语部分通常只包括限定动词,即使有状语,也属任意性状语,即:去掉后并不影响句子结构和意义的完整,如:This bread won’t keep (for a long time). 这种面包不好(长期)存放。 Tom has left. 前面说过,有些句子中的状语是不可缺少的,这种状语被称为必具性状语,从而构成“主 ----动----状”(SVA)句型,但这仅限于少数几个动词的某些用法,因而不是一种主要句型,如: They are staying in a hotel. 他们暂住在一家旅馆里。 3.“主----动-----宾”(SVO)句型: 在这种句型中,谓语动词为只带一个宾语的及物动词,这种动词被称为单宾语及物动词(Monotransitive Verb),如: He kept the money. 他保存着这些钱。 They have left the hotel. 他们已经离开了那家旅馆。 在这种句型中,状语通常也不是必不可少的,但有少数几个及物动词的某些用法要求必具性状语,从而形成了“主----动-----宾-----状”(SVOA)这一在五种基本句型之外的另一种句型,如: The train leaves London at nine. 这列火车九点钟驶离伦敦。

英语常用句型结构大全 英语五种基本句型结构

英语常用句型结构大全英语五种基本句型结构 一年一度的高考即将到来,作为三大主科之一的英语,在考试中所 作占的分数比例很大,但是英语也是许多考生的薄弱科目。那幺想学好英语 的得到高分最起码要掌握英语最基本的常用句型语法等,下面小编就给大家 分享一下英语五种基本句型结构,希望大家学业有成,工作顺利 ?英语中的五种基本句型结构一、句型1:Subject (主语) + Verb (谓语)这种句型中的动词大多是不及物动词,所谓不及物动词,就是这种动词后不可以 直接接宾语。常见的动词如:work, sing, swim, fish, ?jump, arrive, come, die, disappear, cry, happen等。如:1) Li Ming works very hard.李明学习很努力。2) The accident happened yesterday afternoon.事故是昨天下午发生的。3)Spring is coming.4) We have lived in the city for ten years.二、句型2:Subject (主语) + Link. V(系动词) + Predicate(表语)这种句型主要用来表示主语的特点、身份等。其系动词一般可分为下列两类:(1)表示状态。这 样的词有:be, look, seem, smell, taste, sound, keep等。如:1) This kind of food tastes delicious.这种食物吃起来很可口。2) He looked worried just now.刚才他看上去有些焦急。(2)表示变化。这类系动词有:become, turn, get, grow, go等。如:1) Spring comes. It is getting warmer and warmer.春天到了,天气变得越来越暖和。2) The tree has grown much taller than before.这棵树比以前长得高多了。 三、句型3:Subject(主语) + Verb (谓语) + Object (宾语)这种句型中的动词一般为及物动词, 所谓及物动词,就是这种动词后可以直接接宾语,其宾语通常由名词、代词、动词不定式、动名词或从句等来充当。例:1) He took his bag and left.(名词) 他拿着书包离开了。2) Li Lei always helps me when I have difficulties.

[1] 英语语法:英语六大基本句型

英文六大基本句型 一、主系表 1、she is from America -------- where is she from ? 2、The teacher is beautiful ------ how is the teahcer? 3、The teacher is my mother --- who is the teacher? How are you ? ---- I am fine 主系表句型结构:主语+系动词(be)+表语。 主语一般由名词(代词)构成; 表语由介词短语、名词、形容词构成。 注意:一系动词be是连接主语和表语的桥梁,写出的句子不能少了be;/二明白主语和表语的词性,随着学习的深入,以后它变出不定式、动名词、分词等。 二、主谓宾 1、I love you 2、Farmers grow vegetables. 3、Children plant trees 主谓宾句型的结构:主语+谓语动词(do)+宾语。主语一般由名词(代词)构成;宾语由名词构成 注意一,动词do是连接主语和宾语的桥梁,写出的句子不能少了do二,主语和宾语的词性,随着学习的深入,以后它变出不定式、动名词、分词等。 三、主谓 1、Spring comes 2、The accident happened 3、She apologized to me again 4、The teacher listens to the music 主谓句型的结构:主语+谓语动词(do)。这个句子一般没有宾语,因为动词do是不及物动词,不能带宾语。如果非要带宾语,要在不及物动词的后面加介词,比如第3句,第4句的apologize to, listen to.应注意:动词do是不能带宾语的,这种句型中的动词大多是不及物动词,常见的有:appear, apologize,arrive, come, die, disappear, exist, fall, happen, rise,等等,如果要带宾语,必须加介词,英语中的一些动词词组就是这么来的。词典中vi不及物动词必须加介词才能带宾语..vt及物动词 四、主谓宾补 1、He painted the wall white.他把墙漆成白色。 2、We found him an honest person.我们发现他是一个诚实的人。 3、She found the pen on the floor他发现那支笔在地上 主谓宾补句型结构:主语+谓语动词(do)+宾语+补语。相对于主谓宾,这个句子多出了一个补语,这是因为有些话光是主谓宾无法完整表达句子的意思。补语的形式,它可以是形容词,名词,介词短语。

英语常用句型集锦

句型宝典 疑问句型 What is this? 结构︰问句:What+be 动词+this(that…)? 答句:This(that…)+be 动词+a book(pen…)。 说明︰此句型意为“这(那)是什么?这(那)是书(钢笔…)”。what(什么)叫做“疑问词”,用于询问“事物”,通常放在句首,后接be <动词>,再接<主词>,第一个字母w要大写,句尾要加问号(?),位置不可排错。 What is this? This is a chair. 这是什么?这是一张椅子。 What’s this? It’s a book. 这是什么?它是一本书。 What is that? That is a desk. 那是什么?那是一张书桌。 What are these? 结构︰问句:What are+these/those…? 答句:These/Those are+复数名词(+s/es)。 说明︰<主词>与<动词>的形式要一致,is 后面接单数<名词>,are 后面要接复数<名词>。 What are these? These are books. 这些是什么?这些是书。 What are those? Those are cups. 那些是什么?那些是茶杯。 What are they? They are glasses. 它们是什么?它们是玻璃杯。 What are you? 结构︰问句:What+be 动词+主词(人)…? 答句:主词+be 动词+a student…。 说明︰此句型意为“你是做什么事情的?我是学生…”。疑问词what 除了询问事物之外,还可用于询问“人的职业或身分”。be <动词>随<人称代名词>的变化而改变形态,如:I am,we are,you are,he is…。 What are you? I am a student. 你是做什么事情的?我是一名学生。 What is she? She is a teacher. 她是做什么事情的?她是一名教师。 Are you a ...? 结构︰问句:Be 动词(am,are,is)+主词+…? 肯定简答:Yes,主词+am(are,is)。 否定简答:No,主词+am(are,is)not。 说明︰在否定<简答句>中,<主词>和am,is,are 可以缩写;在肯定<简答句>中则不可。 Is he a student? Yes, he is. (No, he isn’t.) 他是学生吗?是的,他是。(不,他不是。)Are you a teacher? Yes, I am. (No, I’m not.) 你是教师吗?是的,我是。(不,我不是。)Is that a clock? Yes, it is. (No, it isn’t.) 那是钟表吗?是的,它是。(不,它不是。)What is your name? 结构︰问句:What+is+所有格+name? 答句:所有格+name+is+名字。 说明︰“my,your,his,her”为单数人称的<所有格>;<所有格>后面必接<名词>,即“<所有格>+<名词>”;<所有格>不可与a,an,this,that,these 或those 紧接一起使用。 What is your name? My name is Sue. 妳叫什么名字?我的名字叫苏。 What is his name? His name is John. 他叫什么名字?他的名字叫约翰。 What is her name? Her name is Jean. 她叫什么名字?她的名字叫珍。 Who is that ...?

高中英语常用语法及句型汇总

高中英语常用语法及句型汇总 【一】高中英语的句型锦集 1.subject(主语)+verb(谓语) 这种句型中的动词大多是不及物动词,所谓不及物动词,就是这种动词后不可以直接接宾语。常见的动词如:work,sing,swim,fish,jump,arrive,come,die,disappear,cry,happen等。 2.subject(主语)+link.v(系动词)+predicate(表语) 这种句型主要用来表示主语的特点、身份等。其系动词一般可分为下列两类: (1)表示状态。这样的词有:be,look,seem,smell,taste,sound,keep 等。 (2)表示变化。这类系动词有:become,turn,get,grow,go等。 3.subject(主语)+verb(谓语)+object(宾语) 这种句型中的动词一般为及物动词,所谓及物动词,就是这种动词后可以直接接宾语,其宾语通常由名词、代词、动词不定式、动名词或从句等来充当。 4.subject(主语)+verb(谓语)+indirectobject(间接宾语)+directobject(直接宾语) 这种句型中,直接宾语为主要宾语,表示动作是对谁做的或为谁做的,在句中不可或缺,常常由表示“物”的名词来充当;间接宾语也被称之为第二宾语,去掉之后,对整个句子的影响不大,多由指“人”的名词或代词承担。引导这类双宾语的常见动词有:buy,pass,lend,give,tell,teach,show,bring,send等。

5.subject(主语)+verb(动词)+object(宾语)+complement(补语) 这种句型中的“宾语+补语”统称为“复合宾语”。宾语补足语的主要作用或者是补充、说明宾语的特点、身份等;或者表示让宾语去完成的动作等。担任补语的常常是名词、形容词、副词、介词短语、分词、动词不定式等。 ●常见的动词有:tell,ask,advise,help,want,wouldlike,order,force,allow等。 ●注意:动词have,make,let,see,hear,notice,feel,watch等后面所接的动词不定式作宾补时,不带to。独立主格结构 【二】高中英语的短语有哪些 1.Ask for……求助向……要……(直接接想要的东西)eg:askyouformybook 2.Ask sb for sth.向某人什么 3.Ask sb.to do sth.询问某人某事 4.Ask sb.not to do sth.叫某人不要做某事 5.At the age of在……岁时 6.At the beginning of………的起初;……的开始 7.At the end of+地点/+时间最后;尽头;末尾 8.At this time of year在每年的这个时候补:at least至少 9.be/feel confident of sth./that clause+从句感觉/对什么有信心,自信 10.be+doing表:1现在进行时2将来时 11.be able to(+v.原)=can(+v.原)能够……

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