A Joint Foundation for Con?guration
in the Semantic Web
Alexander Felfernig,Gerhard Friedrich,Dietmar Jannach,Markus Stumptner,and Markus Zanker
Abstract.Product con?guration is a major commercial applica-
tion of knowledge-based systems,and joint con?guration by multiple
business partners is becoming a key application in today’s highly spe-
cialized economy.The required integration of con?guration knowl-
edge is a challenging task due to the variety of knowledge represen-
tation formalisms used in commercial con?gurators.Ontology lan-
guages such as DAML+OIL provide an infrastructure for the Seman-
tic Web with the goal of intelligent information integration.The aim
of this paper is to show the applicability of such languages for build-
ing con?guration knowledge bases.We join the two major streams in
knowledge-based con?guration(description logics on one hand and
predicate logic,including constraint-based and resource-balancing
techniques on the other)by giving a description logic based de?ni-
tion of a con?guration task and showing its equivalence with existing
consistency-based de?nitions.We show that Semantic Web ontology
languages can be applied to con?guration by formalizing language
elements relevant for building con?guration knowledge bases and
discuss extensions needed in order to provide full?edged con?gu-
ration knowledge representation.The result is a common basis for
current con?guration approaches on the Semantic Web that is neces-
sary for the provision of joint con?guration services.
1Introduction
Knowledge-based con?guration has a long history as a successful
AI application area(e.g.,[3,10,12,13,15,19]).Starting with rule-
based systems such as R1/XCON[3],various higher level represen-
tation formalisms were developed to exploit the advantages of more
concise representation,faster application development,higher main-
tainability and more?exible reasoning.Although these representa-
tions have proven their applicability in various real world applica-
tions,the heterogeneity of con?guration knowledge representation
is the major obstacle to incorporating con?guration technology in
eCommerce environments.The trend towards highly specialized so-
lution providers results in a situation where different con?gurators of
complex products and services must be integrated in order to trans-
parently support distributed con?guration problem solving.
For this integration,con?gurators must have a clear common un-
derstanding of the problem de?nition and the semantics of the ex-
changed knowledge.Consequently,it is necessary to agree on the
de?nition of a con?guration problem and its solution.Of the two
current main streams in representing and solving con?guration prob-
For presentation purposes we employ OIL text-this representation can
easily be transformed into a corresponding DAML+OIL representation.
Note that these differ somewhat from the con?guration ontology that was
described for demonstration purposes in[11].
1
duce an example that provides an overview of the modeling concepts required for building con?guration knowledge bases.In Section3we give a description logics based de?nition of a con?guration task and show its equivalence to the consistency-based de?nition given in[8]. In Section4we describe an OIL-based formalization of the modeling concepts presented in Section2and summarize the results.Section5 closes with conclusions.
2Con?guration domain speci?c modeling concepts In the following we discuss a set of relevant modeling concepts for building con?guration knowledge bases.These concepts are ex-tracted from the con?guration ontologies de?ned in[7,17].Figure 1shows the simpli?ed structure of a con?gurable Computer system which is composed of the following representation concepts. Component types represent the parts,a?nal product is built of-they are characterized by attributes(e.g.,the component type CPU is characterized by the attribute clockrate).Component types with a similar structure are arranged in a generalization hierarchy and rep-resent choices for the con?gurable product(e.g.,in the?nal con-?guration an instance of CPU can be either a CPU1or a CPU2). Part-whole relationships can be considered as bill-of-material repre-sentations semantically enriched with multiplicities,stating a range of how many subparts an aggregate can consist of(e.g.,a MB must contain at least one CPU and at most two CPUs).In addition to the number and types of different components,the product topology may be important in a?nal con?guration as well,i.e.,how the components are interconnected to each other(e.g.,which videoport is used in the con?guration to connect the Videocard with the Screen). Additionally,a set of constraints speci?es allowed combinations of component-and attribute settings in the?nal con?guration.Some component types cannot be used in the same?nal con?guration(they are incompatible).E.g.,we can impose the constraint on the product structure of Figure1that a CPU1is incompatible with a mother-board MB2.In some cases,the existence of a component of a certain type requires the existence of an instance of another speci?c type. Regarding the product structure of Figure1,we can impose the con-straint that the existence of a CPU2requires the existence of a MB2. Finally,parts of a con?guration problem can be interpreted as a re-source balancing task,where some of the components are producers and others are consumers.In the?nal con?guration,consumers and producers must be balanced w.r.t.some resource balancing criteria-e.g.,the amount of installed hard-disk capacity is the upper bound for the capacity requirements of the installed software.In Section4 we will show how to represent these concepts in extended OIL[9]. 3De?ning con?guration tasks
For the description of a con?guration task we employ a descrip-tion logic language(e.g.,OIL)starting from a schema
of disjoint sets of names for concepts,roles,and individuals[5].Concepts can be seen as unary predicates de?ning classes(component types).Roles are used to express relationships between different elements of a domain.Finally,individuals are spe-ci?c named elements of the domain5.
De?nition1(Con?guration problem in description logic):In general we assume a con?guration problem is described by a triple
.represents the domain
leaf concepts of a generalization hierarchy and speci?c relationships (e.g.,to manufacture the?nal system we only need to know the most
speci?c type for each component and its connections).
The semantics of description terms are usually given denotation-ally using an interpretation,where is a domain (non-empty universe)of values,and a mapping from concept de-scriptions to subsets of the domain,and from role descriptions to sets of2-tuples over the domain.The mapping also associates with every individual name in some distinct value in.The reason for this distinctness is the unique name assumption(UNA)we employ in our formalism.We require the UNA for concepts and roles which describe con?gurations in order to make sure that different identi?ers for individuals(e.g.,modules of a system)refer to different individu-als.This UNA can be lifted if necessary for concepts and roles which are not used to describe con?gurations.In the following we give a de-scription logic based de?nition of a con?guration problem and show its equivalence with consistency-based de?nitions given in the litera-ture[8].This de?nition serves as a joint foundation of con?guration knowledge representation in the Semantic Web.
De?nition2(Valid con?guration in description logic):Let be a model of a con?guration knowledge base,
a con?guration language,and
a description of a con?guration.
is a set of tuples for every, where is the set of individu-als of concept.These individuals identify components in an ac-tual con?guration.is a set of tuples
for every where
is the set of tuples of role de?ning the relation of components in an actual con?guration.
Example2:A valid con?guration for our example knowl-edge base is=
mb-of-cpu
.
We also have to describe component parameter settings in addi-tion to components and their https://www.doczj.com/doc/e48464318.html,ing description logics, parameter settings of components are modeled by special functional roles(also called features)expressing the relation between the com-ponent and the data value assigned to a particular attribute.There-fore,component structure and parameter settings can be treated in a uniform manner except that the parameter values come from some data value domain[16]disjunct from the individuals in .
In addition to the de?nition of a valid con?guration given above, we can provide an equivalent characterization based on checking the consistency of a set of axioms.
Remark1:Let be a con?guration knowledge base,
a con?guration language,and
a description of a con?guration. The concepts are de?ned by the component axioms
one-of where The roles are de?ned by the role axioms
product one-of one-of
with
is a valid con?guration iff
is satis?able.
Note that we use the above notation for de?ning the complete ex-tension of roles in order to apply the translation function from de-scription logics to predicate logic de?ned in[5].An alternative to the product constructor would be a constructor that(in a similar manner to the one-of constructor for concepts)permits the enumeration of permissible entries for a role.However,the usual complexity prob-lems with the product constructor do not actually arise since we only apply product to singleton arguments.
Example3:In order to verify that a given con?gura-tion is valid w.r.t.our example,we need to add the axioms one-of,one-of, one-of,one-of,mb-of-cpu
product one-of one-of product one-of one-of product one-of one-of
We now give a consistency-based de?nition of a con?guration problem using predicate logic(this de?nition corresponds to the def-inition given in[8])and show the equivalence with the description logic based de?nition given before.
De?nition3(Con?guration problem in predicate logic):In general we assume a con?guration problem is described by a triple where and are logical sentences and is a set of predicate symbols.represents the domain description and speci?es the particular system requirements.A con?gu-ration is described by a set of positive ground literals whose predicate symbols are in the set of.
Example4:For our example,can be expressed by using monadic and dyadic predicates and numerical quanti?ers,i.e.,
mb-of-cpu
mb-of-cpu
mb-of-cpu
.
mb-of-cpu cpu-of-mb.
mb-of-cpu.
.
mb-of-cpu
De?nition4(Consistent con?guration in predicate logic):Given a con?guration problem,,
,a con?guration is consistent iff
is satis?able.
This de?nition allows determining the consistency of partial con-?gurations,but does not guarantee the completeness of con?gu-rations[8].It is necessary that a con?guration explicitly includes all needed components(and their connections and attribute val-ues),in order to assemble a correctly functioning system.We need to introduce an explicit formula for each predicate symbol in
to enforce its completeness property.In order to stay within?rst order logic,we model the property by?rst order for-mulae.For our example we have to add the completeness axiom
for the predicate and similar axioms for and mb-of-cpu.
3
Note that serves as a macro which is expanded based on the elements in.We refer to extended by completeness axioms as LOG. Example5:
mb-of-cpu
mb-of-cpu mb-of-cpu
The completeness axiom for is
,where un-satis?able literals are deleted.
De?nition5(Valid con?guration in predicate logic):Let ,,be a con?guration problem.
A con?guration is valid iff
LOG is satis?able.
Note that in Example5is a valid con?guration.
In order to show the equivalence of valid con?gurations for de-
scription logic and predicate logic we apply a translation function that maps description logics to predicate logic,i.e.,axioms to formulas with no free variables,concepts to formulas with one free
variable,and roles to formulas with two free variables and. Borgida[5]provides such a translation function such that concepts,roles,terms,and axioms are translated into equivalent for-
mulas in predicate logic.where is satis?able iff is satis?able.
Remark2(Equivalence of con?guration problems):
Let where each concept is in-terpreted as monadic and each role is interpreted as dyadic predi-cate.describes the actual con?guration by two sets of facts COMP-facts ROLE-facts.The construction of is based on
where COMP-facts
and ROLE-facts
.,and.
is a valid con?guration for
iff is a valid
con?guration for.
Remark2follows from Remark1and the equivalence property
of the translation function.Note that the completeness axioms cor-
respond exactly to the translation of the axioms and by applying the translation function proposed in[5]. From the equivalence of con?guration problems follow two impor-tant consequences.First,the two main streams in solving con?gura-tion problems based on description logics on the one hand and?rst order predicate or propositional logic on the other hand can be eas-ily transformed to each other.Second,since description logics with-out transitive closure are equally expressive to dyadic predicate logic with at most three(counting)quanti?ers[5]it follows that the predi-cate logic based approach is strictly more expressive than the descrip-tion logics based approach,implying that certain logic constructions have to be simulated by more complex description logic construc-tions,and also that certain complex structural restrictions[6]will not be expressible in the language directly but will have to be incorpo-rated using a more expressive assertional language.
4Building con?guration knowledge bases for the Semantic Web
In the following we show how to represent the con?guration domain speci?c modeling concepts discussed in Section2using OIL. Component types.The representation of component types is straightforward and has already been shown in https://www.doczj.com/doc/e48464318.html,po-
nent types are transformed into corresponding concepts,attributes into role de?nitions constraining datatype and cardinality(the cardi-nality of attribute roles is set to1).Attributes as well as abstract roles are inherited by the de?ned subconcepts.In most con?guration envi-ronments the semantics of a generalization hierarchy are disjunctive (disjoint concept)and complete by default(each instance of a super-type is also an instance of exactly one of its subtypes).
Part-whole relationships.Part-whole relationships play an im-portant role in many application domains having quite different se-mantics(see[1],[16]).Basically,a part-whole relationship can be expressed using the two roles PartOf and HasPart,where PartOf is the inverse role of HasPart.In OIL or DAML+OIL we can de-?ne-depending on the application domain-different semantics for part-whole relationships by imposing restrictions on the usage of the corresponding roles.Sattler[16]presents an extension of the basic description logic with concepts for adequate representation of part-whole relationships-in this context a categorization of different facets of part-whole relationships is given.In our working example (Figure1)we only allow part-whole relationships where a compo-nent is part-of exactly one other component(this is also denoted as exclusive part-whole relationship).Such exclusivity restrictions can be introduced by restricting the cardinality of the corresponding role to1,e.g.,slot-constraint mb-of-cpu cardinality1MB,where the role mb-of-cpu must be interpreted as a subslot of the role PartOf.
Furthermore,restrictions concerning the cardinality of parts must be added to the concept de?nition of the whole,e.g.,slot-constraint cpu-of-mb min-cardinality1CPU(max-cardinality2CPU).
Port connections.As mentioned above,certain predicate logic constructs must be simulated by more complex description logic ar-rangements[5].In terms of predicate logic,port connections can be represented using a predicate conn(),i.e.,component is connected via port with component via port-e.g., conn()describes a connection between of and
of.In order to represent port-based connections,we have to introduce a Port concept,which is characterized by a role indi-cating the related component concept(role compnt)and a role which indicates the used portname of the connection(role portname)-addi-tionally,a role conn indicates the connection to the second involved Port concept.Although a representation of port connections is pos-sible with OIL or DAML+OIL,the original knowledge of domain experts is split into multiple pieces of knowledge which are hard for these domain experts to understand.Also,note that the connections via such a connection object must be unique and therefore the roles must be bidirectionally de?ned using the inverse role constructor.
The constraint that a Videocard must be connected via
with a Screen via can be formulated as
Example6:Videocard:(slot-constraint videoport has-value((slot-constraint portname has-value(one-of videoport2))and(slot-constraint conn has-value((slot-constraint compnt has-value Screen)and(slot-constraint portname has-value(one-of screen-port1)))))).
The constituting elements of such port constraints are navigations representing role compositions between connected concepts.
Navigation in product structure.In the following we discuss a set of representative constraint concepts which are frequently used in the con?guration domain[7,17].The constraints consist of navi-gation expressions over concepts which are represented by complex paths over abstract roles.
De?nition6(Navigation expression):Given two concepts and,a navigation expression from to is formulated as a
4
sequence of existential role quanti?cations
(slot-constraint has-value(slot-constraint has-value...(slot-constraint has-value))),
where<,,...,>denotes a sequence of roles along the nav-
igation path from to(is a role of and is in the range of).In the following we use the expression navpath(,)as short hand notation for a navigation path concept from to.
De?nition7(Common root):A concept is denoted as com-mon root of a set of concepts,if there exists a navigation path from C R to each concept of C.
Incompatibilities.An incompatibility constraint between con-cepts,,...,can be expressed as:not(navpath(,) and navpath(,)...and navpath(,)),where is the common root of,,...,in.
Example7(IDEUnit incompatible with MB2):Computer: not((slot-constraint hdunit-of-computer has-value IDEUnit)and (slot-constraint mb-of-computer has-value MB2)) Requirements.A requires dependency between concepts and (requires)can be expressed as:not(navpath(,)) or navpath(,)with the common root of,in. Similar to incompatibilities,requirements can be extended by intro-ducing further navigation paths on the LHS and RHS of a requires dependency,e.g.requires.
Example8(SCSIUnit requires MB1):Computer:((not(slot-constraint hdunit-of-computer has-value SCSIUnit))or(slot-constraint mb-of-computer has-value MB1))
Resource balancing.Resource constraints can be formulated us-ing aggregation functions as proposed in[2].We assume the exis-tence of a value domain,a set of predicate symbols asso-ciated with binary relations(typically,,=,,)over, and a set of aggregation functions(typically, ,;the last being identity in the case where we want to com-pare to a single?xed value instead of to an aggregate).Concerning the path leading to the concept whose feature values are aggregated, the de?nition of[2]requires that all but the last one of the roles in this path must be features.
Let<,,...,,>and<,,...,,>be navi-gation expressions with as common root leading to the consumer (producer)concepts().Furthermore,let,be features of and and be an aggregation function.We can express a resource constraint as:...
...according to[2].
Generally,if two aggregates are compared,one interprets the set that has to produce a smaller value as the set of consumers,and the set that has to produce a larger value as the set of producers.
Now we can de?ne a concept Computer that comes equipped with a set of HDUnits that provide a corresponding hard-disk capacity and a set of software components that need hard-disk capacity.We ex-press the requirement that the total hard-disk capacity consumed by software cannot exceed the installed hard-disk capacity.In this case navigation expressions only consist of two elements,consequently hdcapacity must be a feature,while hdunit-of-computer is a general role.The last line is the actual resource constraint.
Example9(swcapacity hdcapacity):
Software:slot-def swcapacity range(min0)properties functional HDUnit:slot-def hdcapacity range(min0)properties functional Computer:slot-def hdunit-of-computer range HDUnit
slot-def sw-of-computer range Software
lesseq(sum(sw-of-computer swcapacity),
sum(hdunit-of-computer hdcapacity))
Analysis.While the basic frame structure and formal basis of
description logics based languages makes them one of the natural choice for con?guration representation,certain demands on expres-siveness must be met.The current versions of OIL and DAML+OIL do not support aggregation functions which are fundamental repre-sentation concepts frequently used in the con?guration domain.Sat-tler and Baader[2]provided concrete domains and aggregation func-tions over them as extensions to the basic description logic.
In addition to aggregation functions,built-in predicates must be al-lowed in order to support comparisons on the results of aggregation functions as well as on local features.Since trivial structural condi-tions lead to de?nitional overhead(e.g.,when de?ning restrictions on port connections),additional concepts must be provided allow-ing the de?nition of roles with arity greater than two;the description of more complex structural properties(see[6])would be supported by permitting the usage of variables.As far as the de?nition of rule languages for expressing detailed con?guration knowledge on top of DAML+OIL is concerned,we must stress that such a language must allow disjuncts of positive literals when writing the constraint in clausal form,e.g.,to express alternative port connections.
Happily,most of the required means of expression are already available in the Description Logic designer’s toolbox;however,the degree of expressivity required also leads to problems w.r.t.to decid-ability of basic properties such as satis?ability or subsumption[2].
State-of-the-art con?gurators achieve decidability by putting a pre-de?ned limit on the number of individuals and allowing only?nite domains of values for features(constraint variables).Furthermore, only?xed concept hierarchies are allowed(as part catalogues are typically considered unchangeable),which reduces the importance of subsumption versus that of A-Box reasoning.
5Conclusions
In this paper we have shown how to apply Semantic Web ontology representation languages for con?guration knowledge representation and integration.We gave a description logic based de?nition of a con-?guration problem and showed its equivalence with corresponding consistency-based de?nitions.A consequence of this equivalence is that con?guration problems represented in description logics can eas-ily be transformed into con?guration problems represented in pred-icate logic or simpli?ed variants thereof(and vice-versa).Conse-quently,we provide a common foundation that enables joint research activities and exploration of results.With respect to ongoing efforts to extend DAML+OIL our paper contributes a set of criteria which must be ful?lled in order to use such a language for full-?edged con-?guration knowledge representation.Thus DAML+OIL has the op-portunity for being a standard knowledge representation language for the con?guration domain.
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6
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高中英语选修 6 Unit 1 A SHORT HISTORY OF WESTERN PAINTING Art is influenced by the customs and faith of a people. Styles in Western art have changed many times. As there are so many different styles of Western art, it would be impossible to describe all of them in such a short text. Consequently, this text will describe only the most important ones. Starting from the sixth century AD. The Middle Ages(5th to the 15th century AD) During the Middle Ages, the main aim of painters was to represent religious themes. A conventional artistof this period was not interested in showing nature and people as they really were. A typical picture at this time was full of religious symbols, which created a feeling of respect and love for God. But it was evident that ideas were changing in the 13th century when painters like Giotto di Bondone began to paint religious scenes in a more realistic way. The Renaissance(15th to 16th century) During the Renaissance, new ideas and values gradually replaced those held in the Middle Ages. People began to concentrate less on
英语选修六课文翻译 第五单元
英语选修六课文翻译第五单元 reading An exciting job I have the greatest job in the world. travel to unusual places and work alongside people from all over the world sometimes working outdoors sometimes in an office sometimes using scientific equipment and sometimes meeting local people and tourists I am never bored although my job is occasionally dangerous I don't mind because danger excites me and makes me feel alive However the most important thing about my job is that I heIp protect ordinary people from one of the most powerful forces on earth-the volcano. I was appointed as a volcanologist working for the Hawaiian Volcano Observatory (HVO) twenty years ago My job is collecting information for a database about Mount KiLauea which is one of the most active volcanoes in Hawaii Having collected and evaluated the information I help oyher scientists to predict where lava from the path of the lava can be warned to leave their houses Unfortunately we cannot move their homes out of the way and many houses have been covered with lava or burned to the ground. When boiling rock erupts from a volcano and crashes back to earth, it causes less damage than you might imagine. This is because no one lives near the top of Mount Kilauea, where the rocks fall. The lava that flows slowly like a wave down the mountain causes far more damage because it buries everything in its path under the molten rock. However, the eruption itself is really exciting to watch and I shall never forget my first sight of one. It was in the second week after I arrived in Hawaii. Having worked hard all day, I went to bed early. I was fast asleep when suddenly my bed began shaking and I heard a strange sound, like a railway train passing my window. Having experienced quite a few earthquakes in Hawaii already, I didn't take much notice. I was about to go back to sleep when suddenly my bedroom became as bright as day. I ran out of the house into the back garden where I could see Mount Kilauea in the distance. There had been an eruption from the side of the mountain and red hot lava was fountaining hundreds of metres into the air. It was an absolutely fantastic sight. The day after this eruption I was lucky enough to have a much closer look at it. Two other scientists and I were driven up the mountain and dropped as close as possible to the crater that had been formed duing the eruption. Having earlier collected special clothes from the observatory, we put them on before we went any closer. All three of us looked like spacemen. We had white protective suits that covered our whole body, helmets,big boots and special gloves. It was not easy to walk in these suits, but we slowly made our way to the edge of the crater and looked down into the red, boiling centre. The other two climbed down into the crater to collect some lava for later study, but this being my first experience, I stayed at the top and watched them.
高二英语教学设计 Book6 Unit 5 Reading An Exciting Job 1.教学目标（Teaching Goals）: a. To know how to read some words and phrases. b. To grasp and remember the detailed information of the reading material . c. To understand the general idea of the passage. d. To develop some basic reading skills. 2.教学重难点: a.. To understand the general idea of the passage. b. To develop some basic reading skills. Step I Lead-in and Pre-reading Let’s share a movie T: What’s happened in the movie? S: A volcano was erupting. All of them felt frightened/surprised/astonished/scared…… T: What do you think of volcano eruption and what can we do about it? S: A volcano eruption can do great damage to human beings. It seems that we human beings are powerless in front of these natural forces. But it can be predicted and damage can be reduced. T: Who will do this kind of job and what do you think of the job? S: volcanologist. It’s dangerous. T: I think it’s exciting. Ok, this class, let’s learn An Exciting Job. At first, I want to show you the goals of this class Step ⅡPre-reading Let the students take out their papers and check them in groups, and then write their answers on the blackboard (Self-learning) some words and phrases：volcano, erupt, alongside, appoint, equipment, volcanologist, database, evaluate, excite, fantastic, fountain, absolutely, unfortunately, potential, be compared with..., protect...from..., be appointed as, burn to the ground, be about to do sth., make one’s way. Check their answers and then let them lead the reading. Step III Fast-reading 这是一篇记叙文，一位火山学家的自述。作者首先介绍了他的工作性质，说明他热爱该项工作的主要原因是能帮助人们免遭火山袭击。然后，作者介绍了和另外二位科学家一道来到火山口的经历。最后，作者表达了他对自己工作的热情。许多年后，火山对他的吸引力依然不减。 Skimming Ⅰ.Read the passage and answer: (Group4) 1. Does the writer like his job?( Yes.) 2. Where is Mount Kilauea? (It is in Hawaii) 3. What is the volcanologist wearing when getting close to the crater? (He is wearing white protective suits that covered his whole body, helmets, big boots and
Unit5 Reading An Exciting Job 说课稿 Liu Baowei Part 1 My understanding of this lesson The analysis of the teaching material:This lesson is a reading passage. It plays a very important part in the English teaching of this unit. It tells us the writer’s exciting job as a volcanologist. From studying the passage, students can know the basic knowledge of volcano, and enjoy the occupation as a volcanologist. So here are my teaching goals: volcanologist 1. Ability goal: Enable the students to learn about the powerful natural force-volcano and the work as a volcanologist. 2. Learning ability goal: Help the students learn how to analyze the way the writer describes his exciting job. 3. Emotional goal: Make the Students love the nature and love their jobs. Learn how to express fear and anxiety Teaching important points: sentence structures 1. I was about to go back to sleep when suddenly my bedroom became as bright as day. 2. Having studied volcanoes now for more than twenty years, I am still amazed at their beauty as well as their potential to cause great damage. Teaching difficult points: 1. Use your own words to retell the text. 2. Discuss the natural disasters and their love to future jobs. Something about the S tudents: 1. The Students have known something about volcano but they don’t know the detailed information. 2. They are lack of vocabulary. 3. They don’t often use English to express themselves and communicate with others.
我的工作是世界上最伟大的工作。我跑的地方是稀罕奇特的地方，我见到的是世界各地有趣味的人们，有时在室外工作，有时在办公室里，有时工作中要用科学仪器，有时要会见当地百姓和旅游人士。但是我从不感到厌烦。虽然我的工作偶尔也有危险，但是我并不在乎，因为危险能激励我，使我感到有活力。然而，最重要的是，通过我的工作能保护人们免遭世界最大的自然威力之一，也就是火山的威胁。 我是一名火山学家，在夏威夷火山观测站（HVO）工作。我的主要任务是收集有关基拉韦厄火山的信息，这是夏威夷最活跃的火山之一。收集和评估了这些信息之后，我就帮助其他科学家一起预测下次火山熔岩将往何处流，流速是多少。我们的工作拯救了许多人的生命，因为熔岩要流经之地，老百姓都可以得到离开家园的通知。遗憾的是，我们不可能把他们的家搬离岩浆流过的地方，因此，许多房屋被熔岩淹没，或者焚烧殆尽。当滚烫沸腾的岩石从火山喷发出来并撞回地面时，它所造成的损失比想象的要小些，这是因为在岩石下落的基拉韦厄火山顶附近无人居住。而顺着山坡下流的火山熔岩造成的损失却大得多，这是因为火山岩浆所流经的地方，一切东西都被掩埋在熔岩下面了。然而火山喷发本身的确是很壮观的，我永远也忘不了我第一次看见火山喷发时的情景。那是在我到达夏威夷后的第二个星期。那天辛辛苦苦地干了一整天，我很早就上床睡觉。我在熟睡中突然感到床铺在摇晃，接着我听到一阵奇怪的声音，就好像一列火车从我的窗外行驶一样。因为我在夏威夷曾经经历过多次地震，所以对这种声音我并不在意。我刚要再睡，突然我的卧室亮如白昼。我赶紧跑出房间，来到后花园，在那儿我能远远地看见基拉韦厄火山。在山坡上，火山爆发了，红色发烫的岩浆像喷泉一样，朝天上喷射达几百米高。真是绝妙的奇景！ 就在这次火山喷发的第二天，我有幸做了一次近距离的观察。我和另外两位科学被送到山顶，在离火山爆发期间形成的火山口最靠近的地方才下车。早先从观测站出发时，就带了一些特制的安全服，于是我们穿上安全服再走近火山口。我们三个人看上去就像宇航员一样，我们都穿着白色的防护服遮住全身，戴上了头盔和特别的手套，还穿了一双大靴子。穿着这些衣服走起路来实在不容易，但我们还是缓缓往火山口的边缘走去，并且向下看到了红红的沸腾的中心。另外，两人攀下火山口，去收集供日后研究用的岩浆，我是第一次经历这样的事，所以留在山顶上观察他们
英语选修六课文翻译第五单元 reading An exciting job I have the greatest job in the world. travel to unusual places and work alongside people from all over the world sometimes working outdoors sometimes in an office sometimes using scientific equipment and sometimes meeting local people and tourists I am never bored although my job is occasionally dangerous I don't mind because danger excites me and makes me feel alive However the most important thing about my job is that I heIp protect ordinary people from one of the most powerful forces on earth-the volcano. I was appointed as a volcanologist working for the Hawaiian Volcano Observatory (HVO) twenty years ago My job is collecting information for a database about Mount KiLauea which is one of the most active volcanoes in Hawaii Having collected and evaluated the information I help oyher scientists to predict where lava from the path of the lava can be warned to leave their houses
新目标英语七年级下册课文Unit04 Coverstion1 A: What does your father do? B: He＇s a reporter. A:Really?That sounds interesting. Coverstion2 A:What does your mother do,Ken? B:She＇s a doctor. A:Really?I want to be a doctor. Coverstion3 A:What does your cousin do? B:You mean my cousin,Mike? A:Yeah,Mike.What does he do? B:He is as shop assistant. 2a,2b Coverstion1 A: Anna,doesyour mother work? B:Yes,she does .She has a new job. A:what does she do? B: Well ,she is as bank clerk,but she wants to be a policewoman. Coverstion2 A:Is that your father here ,Tony?
B:No,he isn't .He's working. B:But it's Saturday night.What does he do? B:He's a waiter Saturday is busy for him. A:Does he like it? B:Yes ,but he really wants to be an actor. Coverstion3 A:Susan,Is that your brother? B:Yes.it is A:What does he do? B:He's a student.He wants to be a doctor. section B , 2a,2b Jenny:So,Betty.what does yor father do? Betty: He's a policeman. Jenny:Do you want to be a policewoman? Betty:Oh,yes.Sometimes it's a little dangerous ,but it's also an exciting job.Jenny, your father is a bank clerk ,right? Jenny:Yes ,he is . Sam:Do you want to be a bank clerk,too? Jenny:No,not really.I want to be a reporter. Sam: Oh,yeah?Why? Jenny:It's very busy,but it's also fun.You meet so many interesting people.What about your father ,Sam. Sam: He's a reporter at the TV station.It's an exciting job,but it's also very difficult.He always has a lot of new things to learn.Iwant to be a reporter ,too
人教版选修Unit 5 The power of nature阅读课教学设计 Learning aims Knowledge aims: Master the useful words and expressions related to the text. Ability aims: Learn about some disasters that are caused by natural forces, how people feel in dangerous situations. Emotion aims: Learn the ways in which humans protect themselves from natural disasters. Step1 Leading-in 1.Where would you like to spend your holiday? 2.What about a volcano? 3.What about doing such dangerous work as part of your job ? https://www.doczj.com/doc/e48464318.html, every part of a volcano. Ash cloud/volcanic ash/ Crater/ Lava /Magma chamber 【设计意图】通过图片激发学生兴趣，引出本单元的话题，要求学生通过讨论, 了解火山基本信息，引出火山文化背景，为后面的阅读做铺垫。利用头脑风暴法收集学生对课文内容的预测并板书下来。文内容进行预测，培养学生预测阅读内容的能力。同时通过预测激起进一步探究 Step2. Skimming What’s the main topic of the article?
Unit1 SectionA 1a Canada, France ,Japan ,the United States ,Australia, Singapore ,the United Kingdom,China 1b Boy1:Where is you pen pal from,Mike? Boy2:He's from Canada. Boy1:Really?My pen pal's from Australia.How about you,Lily?Where's your pen pal from? Girl1:She's from Japan.Where is Tony's pen pal from? Gril2:I think she's from Singapore. 2b 2c Conversation1 A: Where's you pen pal from, John? B: He's from Japan, A:Oh,really?Where does he live? B: Tokyo. Conversation2 A: Where's your pen pal from, Jodie? B: She's from France. A: Oh, she lives in Pairs. Conversation3 A: Andrew, where's your pen pal from? B: She's from France. A: Uh-huh. Where does she live? B: Oh, She lives in Paris.