Impact of community structure on information transfer

a r X i v :0709.2123v 2 [p h y s i c s .s o c -p h ] 9 J a n 2008

Impact of community structure on information transfer

Leon Danon,1,2Alex Arenas,2and Albert D′?az-Guilera 1

1

Departament de F′?sica Fonamental,Universitat de Barcelona,Marti i Franques 1,08028Barcelona,Spain 2

Departament d’Enginyeria Inform`a tica i Matem`a tiques,

Campus Sescelades,Universitat Rovira i Virgili,43007Tarragona,Spain

The observation that real complex networks have internal structure has important implication for dynamic processes occurring on such topologies.Here we investigate the impact of community structure on a model of information transfer able to deal with both search and congestion simul-taneously.We show that networks with fuzzy community structure are more e?cient in terms of packet delivery that those with pronounced community structure.We also propose an alternative packet routing algorithm which takes advantage of the knowledge of communities to improve in-formation transfer and show that in the context of the model an intermediate level of community structure is optimal.Finally,we show that in a hierarchical network setting,providing knowledge of communities at the level of highest modularity will improve network capacity by the largest amount.

PACS numbers:89.75.Hc,87.23.Ge

I.INTRODUCTION

The continuing intensity that accompanies the study of complex networks has led to many important contri-butions in a variety of scienti?c disciplines (for a recent review see [1]).Speci?cally,the study of transport prop-erties of networks is becoming increasingly important due to the constantly growing amount of information and commodities being transferred through them.A partic-ular focus of these studies is how to make the capacity of the network maximal while minimising the delivery time.Both network packet routing strategies and net-work topology play essential parts in tra?c ?ow in net-works.

Traditionally routing strategies have been based on the idea of maintaining routing tables of the best approxima-tion of the shortest paths between nodes.In realistic set-tings,however,the knowledge that any one of the nodes has about the topology of the network will be incom-plete.So,much of the focus in recent studies has been on searchability .In particular,distributed search using only local information has been shown to be e?cient in spatially embedded networks [2,3].Networks with scale-free degree distributions are particularly navigable using local search strategies due to the presence of highly con-nected hubs [4].

However,when the number of search problems the net-work is trying to solve increases,it raises the problem of congestion at central nodes.It has been observed,both in real world networks [5]and in model communication networks [6,7,8,9,10,11,12],that the networks col-lapse when the load is above a certain threshold and the observed transition can be related to the appearance of the 1/f spectrum of the ?uctuations in Internet ?ow data [13,14].

These two problems,search and congestion,that have so far been analysed separately in the literature can be in-corporated in the same communication model.Previous work has contributed a collection of models that capture the essential features of communication processes and are

able to handle these two important issues simultaneously [8,10,15,16].In these models,agents are nodes of a net-work and can interchange information packets along links in the network.Each agent has a certain capability that decreases as the number of packets to deliver increases.The transition from a free phase to a congested phase has been studied for di?erent network architectures in [8,10],whereas in [15]the cost of maintaining communi-cation channels was considered.

The topology of the network also plays a central part in communication processes.In [16]the problem of ?nding optimal network topologies for both search and conges-tion for a ?xed number of nodes and links was tackled.It was found that in the free regime,highly centralised topologies facilitating search are optimal,whereas in the congested regime decentralised topologies which dis-tribute the packet load between nodes are favoured.It has been shown that shortest path routing algorithms are not optimal for scale free networks due to the pres-ence of communication bottlenecks [17]and several al-ternative routing strategies have been proposed to take advantage of the scale-free nature of complex networks [11,18,19,20,21].

On the other hand,many networks found in nature have been observed to have a modular or community https://www.wendangku.net/doc/009562310.html,munities are those subsets of nodes that are more densely linked internally than to the rest of the network.Identifying communities in networks has become a problem which has been tackled by many re-searchers in recent years (see for example [22,23,24],and for reviews see [25,26]).Furthermore,communities are often organised in a hierarchical way [16,27,28,29,30].That is,large communities are often comprised of several smaller communities.Despite all these e?orts,the impact that community structure has on information transfer has not been considered.

The aim of this paper is two-fold:?rstly,we will in-vestigate the e?ect that community structure has on the model of search and congestion,and secondly we will pro-pose an alternative routing strategy and demonstrate its

2

impact in the presence of community structure.In the next section we will describe the model and recall the most important analytical results.In Section II we will consider the e?ect that a modular structure of varying strength has on the behaviour of the model.We will then show how knowledge of this community structure can be taken advantage of to improve transport processes in net-works.And in the?nal section,we give some concluding remarks.

https://www.wendangku.net/doc/009562310.html,MUNICATION MODEL

The communication model considers that the informa-tion?owing through the networks is formed by discrete packets sent from an origin node to a destination node. Each node is an independent agent that can store as many packets as necessary.However,to have a realis-tic picture of communication we must assume that the nodes have a?nite capacity to process and deliver pack-ets.That is,a node will take longer to deliver two pack-ets than just one.A particularly simple example of this would be to assume that nodes are able to deliver one (or any constant number)information packet per time step independent of their load,as in the model of decen-tralised information processing in?rms of Radner[31] and in simple models of computer queues[6,7,9,15], but note that many alternative situations are possible. In the present model,each node has a certain ability to deliver packets which is limited.This limitation in the ability of agents to deliver information can result in con-gestion of the network.When the amount of information is too large,agents are not able to handle all the packets and some of them remain undelivered for extremely long periods of time.The maximum amount of information that a network can manage before collapse gives a mea-sure of the quality of its organisational structure.In this study,the interest is focused on when congestion occurs depending on the topology of the network[15].

The dynamics of the model is as follows.At each time step t,an information packet is created at every node with probabilityρ.Thereforeρis the control pa-rameter:small values ofρcorrespond to low density of packets and high values ofρcorrespond to high density of packets.When a new packet is created,a destina-tion node,di?erent from the origin,is chosen randomly in the network.Thus,during the following time steps t+1,t+2,...,t+T,the packet travels toward its des-tination.Once the packet reaches the destination node, it is delivered and disappears from the network.

The time that a packet remains in the network is re-lated not only to the distance between the source and the target nodes,but also to the amount of packets in its path.Nodes with high loads—i.e.high quantities of accumulated packets—will take longer to deliver pack-ets or,in other words,it will take more time steps for packets to cross regions of the network that are highly congested.In particular,at each time step,all the pack-ets move from their current position,i,to the next node in their path,j,with a probability p ij.This probability p ij is called the quality of the channel between i and j.In this paper,we take the special case that each node is able to send one packet at each time step.It is important to note,however,that the model is not deterministic.Here, a packet which is waiting at a particular node,will be sent with equal probability as any other packet waiting at the same node.

The packets in the present model have a limited radius of knowledge,that is,they are able to determine whether a node within a certain distance r is the destination node. In this case,the packet takes the shortest possible route to the destination,otherwise,it travels down a link cho-sen at random.In this paper we set r=1,so that only nearest neighrbours are recognised.It has been shown in previous work that in the free phase,there is no accu-mulation at any node in the network and the number of packets that arrive at node j is,on average,ρB j/(S?1), where B j is the e?ective betweenness of node j which is de?ned as the fractional number of paths that pack-ets take though node j and S is the number of nodes in the network.A particular node will collapse when ρB j/(S?1)>1and the critical congestion point of the network will be

ρc=

S?1

3

First we employ the networks proposed in

[32].These networks are comprised of 128nodes which are split into four communities of 32nodes each.Pairs of nodes belong-ing to the same community are linked with probability p in ,whereas pairs belonging to di?erent communities are joined with probability p out .The value of p in is chosen so that the average number of links a node has to members of any other community,Z in ,can be controlled.While p in (and therefore Z in )is varied freely,the value of p out is chosen to keep the total average node degree,k ,con-stant,and set to 16.As Z in is increased from zero,the communities become better de?ned and easier to identify.To address the question of hierarchical structure we use a generalisation of the model of generation of net-works with community structure that includes two hier-archical levels of communities as introduced in [27].The graphs are generated as follows:in a set of 256nodes,16compartments are prescribed that will represent our ?rst community organisational level.Each of these sub-communities contains 16nodes each.Furthermore,four second level communities are prescribed,each containing four sub-communities,that is 64nodes each.The inter-nal degree of nodes at the ?rst level Z in 1and the internal degree of nodes at the second level Z in 2are constrained to keep an average degree Z in 1+Z in 2+Z out =18.From now on,networks with two hierarchical levels are indi-cated as Z in 1-Z in 2,e.g.a network with 13-4means 13links with the nodes of its ?rst hierarchical level commu-nity (more internal),4links with the rest of communities that form the second hierarchical level (more external)and 1link with any community of the rest of the net-work.

As a simple measure of structural e?ciency of the net-work in terms of packet transport,we can consider the number of packets present in the network.We allow the dynamics to reach a steady state,which we detect by considering the rate at which the number of packets in-creases in the system.Once this rate becomes small,?uctuating around 0,we have reached the end of the transient.It is important to note that when ρ>ρc the system never reaches a steady state,the mean number of packets keeps growing linearly with time,and the rate never becomes very small.We also average over several realisations,since the number of packets in the system is subject to statistical ?uctuations.

A.Original communication model

First of all we simulate the dynamics of the model de-scribed above,in which the packets have no knowledge of the topology of the network at the level of community structure.Introducing community structure in the net-work topology over which the dynamics occur increases the tra?c load on the nodes which connect communities.This is in agreement with the ?nding that cutting links with the highest betweenness separates communities [22].It follows that the e?ective betweenness of the nodes at

each end of the bridge links will also be increased.As a result,the capacity of the network to deliver packets is reduced in function of how fuzzy the community struc-FIG.1:(colour online)Each point represents the number of packets averaged over 100realisations in the steady state of the dynamics.(a)Number of ?oating packets as a function of ρusing the original search algorithm in networks with one level of community structure.The di?erent colours denote varying levels of community strength as controlled by the pa-rameter Z in and the vertical lines correspond to the analytical prediction of the onset of congestion (Section II,equation 1).(b)Onset of congestion ρc for varying Z in .

From Fig.1we can see that the analytical calculation from Section II,of the onset of congestion ρc agrees very well with the point at which the number of ?oating pack-ets diverges.As the strength of community structure is increased by raising Z in ,ρc is reduced.This seems logi-cal,since the origin and destination of packets are chosen at random.It follows that the probability of creating a packet with both origin and destination in one commu-nity is 1/4.All other packets will necessarily have to pass through at least one central,”bridge”node that connects two communities.This leads to an increase in the number of packets that pass through bridge nodes,increasing its e?ective betweenness.As a result of receiving a dispro-portionate amount of packets,these nodes will collapse at lower values of ρ,leading to a cascade of collapses throughout the network.This e?ect becomes more and more pronounced as Z in increases,so,the stronger the community structure,the lower ρc .

In the case of hierarchical networks,we concentrate on three di?erent network topologies which are particularly instructive,13-4,14-3and 15-2.Once again the ana-lytical calculation corresponds very well to the point at which the number of ?oating packets diverges,see Fig.2.It is worth noting that these three networks have almost the same ρc .This is due to the fact that the average number of links per node between communities of size 64

tion ofρusing the original search in networks with hierar-chical community structure on two levels.The vertical lines correspond to analytical prediction of the onset of congestion.

B.Modifying the communication model Clearly,networks with strong community structure are less e?cient at delivering packets which are oblivious to the underlying topology.But,what happens when we give the search process some information about the com-munity structure?To address this question we propose a simple modi?cation of the way packets are transferred between nodes.

Let us consider a packet generated at node i in com-munity c i with destination node j in community c j.At each step in its path,the packet is given information of the community of neighbouring nodes.Should the packet destination community be the same as that of any of the neighbours of the node that is processing the packet,the packet is sent to one of those neighbours,otherwise it is sent down a link chosen at random.In this way,packets are able to arrive at the destination community without necessarily arriving at the destination node.The idea is that once within the destination community,?nding the destination node is easier.

In Figure3we plot the number of?oating packets in the network at the steady state against the packet injec-tion rateρ.The dynamics are performed on networks with ad-hoc community structure of varying strength, controlled by the parameter Z in,the average number of links internal to the community.When Z in=4the net-work is equivalent to an Erd¨o s-Renyi random graph with 128nodes and16links per node.In this scenario,the original search algorithm performs much better in terms of ability to deliver packets.This seems logical:giving packets information about communities which are not present will not improve the packet’s ability to?nd the againstρ.The four panels depict four networks with varying community strength controlled by the parameter Z in,and the red points show the original search algorithm and the black points denote the modi?ed algorithm incorporating commu-nity information.

destination node.Indeed,for lower values of Z in,this information is detrimental to e?ciency,since the pre-de?ned partitions of the network actually contain fewer internal links,compared to external ones.In this sce-nario,packets are often sent to regions of the network which are less likely to contain the destination node.This is highlighted in Figure4b.where we see that for very low values of Z in the original search algorithm collapses the network at much higher values ofρthan the modi?ed algorithm.

When the strength of the community structure is in-creased,the modi?ed search algorithm improves the e?-ciency of the network considerably.For Z in>8[34],the onset of congestion in terms ofρis considerably higher for the modi?ed search algorithm,and the same network is much more e?cient at delivering packets for all values of Z in>8.In other words,the modi?ed algorithm is able to?nd more e?cient routes to deliver packets and the network is able to handle a much higher load.

In the modi?ed search algorithm,the calculation from Section II(equation1)is still valid,however,the analytic calculation of B?is more involved than in[10].Never-theless we can estimateρc of the network by looking at the point where the number of?oating packets diverges. In Figure4a,ρc is estimated in this fashion.When the communities are extremely well de?ned,say Z in=15,?ow through the network is restricted.So even though the search method of the packets is greatly improved, and they are able to?nd the correct community in a short number of steps,?ow is restricted by the forma-tion of bottlenecks at the interface between two com-munities.It emerges that an intermediate community structure strength,Z in=12shows optimal e?ciency in

FIG.4:(colour online)Onset of collapse for the modi-?ed search algorithm as applied to networks with community structure at a single level.(a)Number of?oating packets as a function ofρfor the modi?ed search.Di?erent colours de-note varying community strengths,controlled by parameter Z in and the vertical lines now denote the estimate of the onset of congestionρc.(b)ρc as a function of internal connectiv-ity Z in for both the original model,r=1,and the modi?ed model,r=1com.

terms ofρc.This suggests that for the?ow to be opti-mal there must be a balance between internal strength of communities and connections to other communities. For the case of networks with hierarchical community structure as described above,community information can now be given at two levels.The packets can be given information about the community structure on the?rst level,that is,they are given knowledge about which com-munity of the four communities of size64the destination node belongs to.From here on,this is denoted as i=4. Alternatively,we can give nodes information on the sec-ond level of community structure,so that packets know which one of the16communities of size16the destina-tion node belongs to,which we denote i=16.

Once information about community structure is given to the packets,the e?ciency of the network to deliver these is increased considerably as in the case of single level community structure.The level of community in-formation which increases the e?cacy of information?ow by the largest amount is dependent on the topology of the https://www.wendangku.net/doc/009562310.html,pared with no community information be-ing given to the packets,i=16increases the values of ρc almost?vefold,in all three networks.In the case of 13-4,ρc is increased from0.0132to0.064.A stronger community structure at the second level,14-3and15-2 does not make much of an impact when i=16,withρc being0.063for both.

However,when information is given at the interme-diate level of community structure,i=4,the di?er-ences become more apparent.For the13-4con?guration,at the second level i=16.The vertical lines represent the analytical calculation as in Section II for the original search algorithm.

community information at this level favours information di?usion more,withρc being0.071,higher than in the i=16case.However in the case of the14-3network, the opposite is true:giving information at the alterna-tive,i=16level is(marginally)more bene?cial.For the 15-2network,giving more precise information causes a considerable improvement.

It is interesting to compare these results with other topological characterisations of complex networks.In particular,the most common measure related to commu-nity structure is the modularity measure,Q,proposed in [32]which measures the quality of a particular partition of a particular network.It is de?ned as follows:

Q= i(e ii?a2i)

where the element i,j of the matrix e represents the fraction of links between communities i and j and a i= j e ij.This value can also be measured at two levels. One is at the?rst level of the hierarchy,where nodes are grouped in4communities of64nodes each,which corre-sponds to the i=4case.The other,corresponding to the i=16case,is considering that the nodes are grouped in 16communities of16nodes each.In the three networks we are considering,we only vary the strength of the sec-ond level of community structure,so for the i=4case, the value of modularity remains constant.For the i=16 case however,the value of Q varies with the strength of the second level.For the13-4network,the?rst level of community structure is a better partition in terms of Q, whereas for14-3and15-2the second level is a better partition.See Table I for values.

For13-4,where the best partition is found at the?rst level of community structure i=4,giving packets in-formation about the same level improves the e?ciency of the network more than giving information at the sec-ond level.For14-3and15-2the opposite is true:in

Net

ρc

i=0i=4i=4

0.0640.660

0.0630.726

0.0630.771

tional Academy of Sciences,USA104,36(2007). [30]M.Sales-Pardo,R.Guimera,A.Moreira,and L.Amaral,

Proceedings of the National Academy of Sciences,USA 104,15224-15229(2007).

[31]R.Radner,Econometrica61,1109(1993).

[32]M.E.J.Newman and M.Girvan,Physical Review E69,

026113(2004).[33]U.Brandes, D.Delling,M.Gaertler,R.Goerke,

M.Hoefer,Z.Nikoloski,and D.Wagner,preprint p.

https://www.wendangku.net/doc/009562310.html,:physics/0608255v2(2006).

[34]Z in=8corresponds to Z out=8,at which point most

community identi?cation algorithms are able to detect the correct structure,[26].

英语介词用法大全

英语介词用法大全 TTA standardization office【TTA 5AB- TTAK 08- TTA 2C】

介词（The Preposition）又叫做前置词，通常置于名词之前。它是一种虚词，不需要重读，在句中不单独作任何句子成分，只表示其后的名词或相当于名词的词语与其他句子成分的关系。中国学生在使用英语进行书面或口头表达时，往往会出现遗漏介词或误用介词的错误，因此各类考试语法的结构部分均有这方面的测试内容。 1. 介词的种类 英语中最常用的介词，按照不同的分类标准可分为以下几类： (1). 简单介词、复合介词和短语介词 ①.简单介词是指单一介词。如： at , in ,of ,by , about , for, from , except , since, near, with 等。②. 复合介词是指由两个简单介词组成的介词。如： Inside, outside , onto, into , throughout, without , as to as for , unpon, except for 等。 ③. 短语介词是指由短语构成的介词。如： In front of , by means o f, on behalf of, in spite of , by way of , in favor of , in regard to 等。 (2). 按词义分类 {1} 表地点（包括动向）的介词。如： About ,above, across, after, along , among, around , at, before, behind, below, beneath, beside, between , beyond ,by, down, from, in, into , near, off, on, over, through, throught, to, towards,, under, up, unpon, with, within , without 等。 {2} 表时间的介词。如： About, after, around , as , at, before , behind , between , by, during, for, from, in, into, of, on, over, past, since, through, throughout, till(until) , to, towards , within 等。 {3} 表除去的介词。如： beside , but, except等。 {4} 表比较的介词。如： As, like, above, over等。 {5} 表反对的介词。如： againt ,with 等。 {6} 表原因、目的的介词。如： for, with, from 等。 {7} 表结果的介词。如： to, with , without 等。 {8} 表手段、方式的介词。如： by, in ,with 等。 {9} 表所属的介词。如： of , with 等。 {10} 表条件的介词。如：

介词in,on.at,for.with,by,of的基本用法

介词用法知多少 介词是英语中最活跃的词类之一。同一个汉语词汇在英语中可译成不同的英语介词。例如汉语中的“用”可译成：（1）用英语（in English）；（2）用小刀（with a knife）；（3）用手工（by hand）；（4）用墨水（in ink）等。所以，千万不要以为记住介词的一两种意思就掌握了这个介词的用法，其实介词的用法非常广泛，搭配能力很强，越是常用的介词，其含义越多。下面就简单介绍几组近义介词的用法及其搭配方法。 一. in, to, on和off在方位名词前的区别 1. in表示A地在B地范围之内。如： Taiwan is in the southeast of China. 2. to表示A地在B地范围之外，即二者之间有距离间隔。如： Japan lies to the east of China. 3. on表示A地与B地接壤、毗邻。如： North Korea is on the east of China. 4. off表示“离……一些距离或离……不远的海上”。如： They arrived at a house off the main road. New Zealand lies off the eastern coast of Australia. 二. at, in, on, by和through在表示时间上的区别 1. at指时间表示： （1）时间的一点、时刻等。如： They came home at sunrise （at noon, at midnight, at ten o’clock, at daybreak, at dawn）. （2）较短暂的一段时间。可指某个节日或被认为是一年中标志大事的日子。如： He went home at Christmas （at New Year, at the Spring Festival, at night）. 2. in指时间表示： （1）在某个较长的时间（如世纪、朝代、年、月、季节以及泛指的上午、下午或傍晚等）内。如： in 2004, in March, in spring, in the morning, in the evening, etc （2）在一段时间之后。一般情况下，用于将来时，谓语动词为瞬间动词，意为“在……以后”。如： He will arrive in two hours. 谓语动词为延续性动词时，in意为“在……以内”。如： These products will be produced in a month. 注意：after用于将来时间也指一段时间之后，但其后的时间是“一点”，而不是“一段”。如： He will arrive after two o’clock. 3. on指时间表示： （1）具体的时日和一个特定的时间，如某日、某节日、星期几等。如： On Christmas Day（On May 4th）, there will be a celebration. （2）在某个特定的早晨、下午或晚上。如： He arrived at 10 o’clock on the night of the 5th. （3）准时，按时。如： If the train should be on time, I should reach home before dark. 4. by指时间表示： （1）不迟于，在（某时）前。如：

in on at的时间用法和地点用法 完全版

in，on，at的时间用法和地点用法 一、in, on, at的时间用法 ①固定短语： in the morning/afternoon/evening在早晨/下午/傍晚, at noon/night在中午/夜晚, （不强调范围，强调的话用during the night） early in the morning=in the early morning在大清早， late at night在深夜 on the weekend在周末（英式用at the weekend在周末，at weekends每逢周末） on weekdays/weekends在工作日/周末， on school days/nights在上学日/上学的当天晚上， ②不加介词 this, that, last, next, every, one, yesterday, today, tomorrow, tonight，all，most等之前一般不加介词。如， this morning 今天早晨 （on）that day在那天（that day更常用些） last week上周 next year明年 the next month第二个月（以过去为起点的第二个月，next month以现在为起点的下个月） every day每天 one morning一天早晨 yesterday afternoon昨天下午 tomorrow morning明天早晨 all day/morning/night整天/整个早晨/整晚（等于the whole day/morning/night） most of the time （在）大多数时间 ③一般规则 除了前两点特殊用法之外，其他≤一天，用on，＞一天用in，在具体时刻或在某时用at（不强调时间范围） 关于on 生日、on my ninth birthday在我九岁生日那天 节日、on Teachers’Day在教师节 （注意：节日里有表人的词汇先复数再加s’所有格，如on Children’s Day, on Women’s Day, on Teachers Day有四个节日强调单数之意思，on Mother’s Day, on Father’s Day, on April Fool’s Day, on Valenti Day） 星期、on Sunday在周日，on Sunday morning在周日早晨 on the last Friday of each month 在每个月的最后一个星期五 日期、on June 2nd在六月二日 on the second (of June 2nd) 在六月的第二天即在六月二日 on the morning of June 2nd在六月二日的早晨，on a rainy morning在一个多雨的早晨 on a certain day 在某天 on the second day在第二天（以过去某天为参照） 注意：on Sunday在周日，on Sundays每逢周日（用复数表每逢之意），every Sunday每个周日，基本一个意思。 on a school day 在某个上学日，on school days每逢上学日。on the weekend在周末，on weekends每逢 周末。 关于in in June在六月 in June, 2010在2010年六月

介词的用法

（一）介词概述 介词是一种虚词，在句子中不单独作任何句子成分。它是一种表示名词和句中其他词之间关系的词。它常和名词、动词、形容词等搭配，构成固定短语，表示不同意思。介词还可以与名词构成介词短语，表示方位、方向、时间、地点、方式、原因等。这些介词短语在句中可充当定语、状语、补语等。2000—2005年的中考中主要考了形容词与介词的搭配：如：be famous for；表示时间的介词，如：at night；动词与介词的搭配，如：arrive in/have dinner with sb.；表示方式、手段的介词，如：by phone/in English. （二）基础知识梳理 1．名词与介词的搭配 a bit of有一点儿 a couple of两个、几个 a kind of一种、一类cover an area of占地面积 have pity on sb.怜悯某人huge amounts of大量的 make friends with与……交朋友make fun of拿……开玩笑 meet the needs of迎合……的需要one after another一个接一个；连续地 play a trick on捉弄the week after next下下周 2．动词与介词的搭配 agree with sb.同意某人的意见apologize to sb. for sth.为某事向某人道歉arrive at/in a place到达某地ask for请求、寻求 be covered with被……所覆盖be made of由……制成 be made up of由……组成belong to属于 break into破门而人、闯入 call on拜访 care for照顾、喜欢carry out执行 check in办理登机come across被理解；遇见 come from出生于、来自come on跟我来、走吧

at,in与on的用法区别

at, in与on的用法区别 1. 表示时间，注意以下用法： ①表示时间的某一点、某一时刻或年龄等用at： I get up at six in the morning. 我早上六点钟起床。 He got married at the age of 25. 他25 岁结婚。 ②泛指一般意义的上午、下午或晚上以及月或年等较长的时间，一般用in：We watch TV in the evening. 我们晚上看电视。 He went to Japan in 1946. 他于1946 去了日本。 ③若表示星期几或某一特定的日期，则用on： He left here on the fifth of May. 他于5 月5 日离开这儿。 2. 表示地点、场所、位置等，注意以下用法： ①表示某一点位置，用at： We live at No 87 Beijing Road. 我们住在北京路87 号。 The hospital is at the end of the street. 医院在这条街的尽头。 与名词所有格连用表示地点，也用at。如： at my sister’s 在我姐姐家 at the doctor’s 在医务室 ②表示空间或范围，用in： What’s in the box? 这盒子里有什么? He lives in Paris with his wife. 他同他妻子住在巴黎。 但有时两者可换用：

The meeting was held at [in] the hotel. 会议在宾馆举行。 ③at与in的另一个区别是：at多用于指较小的地方，而in多用于指较大的地方：in Shanghai 在上海at the station 在车站 ④介词on 用于地点，主要指在某物的表面： What’s on the table? 桌上有什么? There’s a wallet lying on the ground. 地上有个钱包。 【注】在少数搭配中，也用介词on： He works on a farm. 他在农场工作。 3. 在某些搭配中，三者的区别与英国英语和美国英语有关： in the street (英) / on the street (美) 在街上 in the road (英) / on the road (美) 在路上 in the team (英) / on the team (美) 在这个队 at the weekend (英) / on the weekend (美) 在周末 at weekends (英) / on weekends (美) 在周末 4. 有时三者的差别与搭配习惯和用法有关： in bed / on the bed 在床上 in the tree (多指树外之物) / on the tree (多指树本身之物) 在树上

In on at 时间用法及练习

In\ on\ at (time) at 用在具体某一时刻eg at 11:00 at 4:30 在节假日的全部日子里at Christmas 习惯用法at noon at weekends\ at the weekend at night at breakfast\lunch\supper on 具体到某一天；某一天的早晨，中午或晚上on May the first on Sunday morning 对具体某一天的早晨，中午，晚上进行详细的描述on a sunny morning on a windy night 节日的当天；星期on Women?s Day on Monday In 用在年；月；季节in spring in 2012 in August 后面+一段时间表示将来时in two days 习惯用法in the morning\in the afternoon\in the evening “\”以this, that, last, next, some, every, one, any,all开始的时间副词之前的at\on\in 省略在today, tomorrow, yesterday, the day after tomorrow, tomorrow morning，yesterday afternoon，the day before yesterday 之前的介词必须省略 Practice ___ summer ____ 2012 ____ supper ___ 4:00 ___ June the first ___yesterday morning ____ New Year?s Day ___ Women?s Day ___ the morning ____ the morning of July the first ____ 2014 ___ tomorrow morning ____ midnight 1.—What are you doing ____ Sunday? And what is your wife doing ___ the weekend? 2. He?ll see you ____ Monday. And he…ll see your brother ____next Monday. 3. They often go out ___ the evenings. But they don?t go out ____ Sunday evenings. 4. Do you work ____ Fridays? Does she work _____ every Friday? 5. They usually have a long holiday ___ summer. But their son can only have a short holiday ___ Christmas. 6. Paul got married ___ 2010, He got married ___ 9 o?clock ___ 19 May 2010. His brother got married ___ May, 2011. His sister is getting married ___ this year. 1.—When will Mr Black come to Beijing? ---_______ September 5 A. on B. to C. at D. in 2. The twins were born ____ a Friday evening. A. on B. of C. at D. in 3. It?s the best time to plant ____ spring. A. on B. in C. at D.\ 4. ____ the age of twelve, Edison began selling newspaper on train. A. On B. At C. In D.By 5. She has been an English teacher ____ 2000. A. for B. since C. in D.on 6.I have studied English _____ 2003. A. since B. for C. from D.in

介词on、in、at 的用法

1）in 把地方、地点、位置当作一个范围或一个封闭的空间： 1. I live in Beijing. 我住在北京。(大城市用in) 2. I live in England, at London. 我住在英国伦敦。(England大过London喔) 3. I live in a big city, my brother lives at a small town. 我住在大城市，我 哥哥住在一个小市镇。(如果把city看做一个圆圈，small town就成一个点。因此就in a city, at a small town. 呵呵) 4. We have a meeting in Beijing. 我们有北京有一个会议。 5. Mars is in the Solar System. 火星在太阳系里。 6. in a car 乘汽车(不是on a car 也不是by a car 喔) 7. in a taxi 乘的士(不是on a taxi 或by a taxi ) 8. in a helicopter 乘直升机 9. in a boat 乘小船 10. in a lift (elevator) 乘电梯(电梯像个笼子，当然要用in 啦) 11. in the newspaper 在报上 12. in the sky 在空中 13. in the bed 在床上(也可用on the bed) 14. in the bedroom/ class/ library/ school 在寝室/课室/图书馆/学校 . 2）.at 把地方、地点、位置当作一个“点”： 1. The begger is sitting at the corner. 那乞丐坐在角落里。 2. Jane is waiting for you at the bus stop. Jane在巴士站等你。 3. at home 在家 4. Who's standing there at the door? 谁站在门口？ 5. at the top of the page 在一页的上面 6. The shop is at the end of the road. 那商店就在路的尾端。 7. at the entrance 在进口处 8. at the crossroads 在十字路口 9. When will you arrive at the office? 你什么时候会到公司呢？ 10. I'm in France, at Paris. 我住在法国巴黎。(相对法国来讲，巴黎只是一个 “点”) 11. There is a small hut at the foot of the hill. 山脚下有一座小屋子。 12. My aunt lives at 55 Boretz Road in Durham. 我的姑妈住在Durham,Boretz 路门牌55号。(地址要用at，不能用in) 13. at the side 在一边 14. at reception 在招待会上 15. I'm at work. 我在工作。 16. at class/ home/ the library/ the office/ school 在班上/家里/图书馆/公 司/学校 (3). on 把地方、地点、位置当作一个平面：

2时间介词in,on,at的用法

介词in on at 表示时间的用法及区别 Step1 Teaching Aims 教学生掌握时间介词in,on和at的区别及用法。 Step2 Teaching Key and Difficult Points 教学生掌握时间介词in,on和at的区别及用法。 Step3 Teaching Procedures 1.用in的场合后所接的都是较长时间 (1)表示“在某世纪/某年代/特定世纪某年代/年/季节/月”这个含义时，须用介词in Eg: This machine was invented in the eighteenth century. 这台机器是在18世纪发明的。 、 She came to this city in 1980. 他于1980年来到这个城市。 It often rains here in summer. 夏天这里常常下雨。 (2)表示“从现在起一段时间以后”时，须用介词in。(in+段时间表将来) Eg: They will go to see you in a week. 他们将在一周后去看望你。

I will be back in a month. 我将在一个月后回来。 (3)泛指一般意义的上、下午、晚上用in, in the morning / evening / afternoon Eg: They sometimes play games in the afternoon. 他们有时在下午做游戏。 Don't watch TV too much in the evening. 晚上看电视不要太多。（4）A. 当morning, evening, afternoon被of短语修饰，习惯上应用on, 而不用in. Eg: on the afternoon of August 1st & B. 但若前面的修饰词是early, late时，虽有of短语修饰，习惯上应用in, 而不用on. Eg: in the early morning of September 10th 在9月10的清晨； Early in the morning of National Day, I got up to catch the first bus to the zoo. 国庆节一清早，我便起床去赶到动物园的第一班公共汽车。 2.用on的场合后所接的时间多与日期有关 （1）表示“在具体的某一天”或（在具体的某一天的）早上、中午、晚上”，或“在某一天或某一天的上午，下午，晚上”等，须用介

英语地点介词的正确使用方法

英语地点介词的正确使用方法 地点介词主要有at ，in，on，to，above，over，below，under，beside，behind ，between。它们的用法具体如下： 1、at （1）at通常指小地方：In the afternoon，he finally arrived at home。到下午他终于到家了。 （2）at通常所指范围不太明显，表示“在……附近，旁边”：The ball is at the corner。球搁在角落里。 2、in （1）in通常指大地方：When I was young，I lived in Beijing。我小时候住在北京。 （2）在内部：There is a ball in in the box。盒子里有只球。 （3）表示“在…范围之内”（是从属关系）： Guangdong lies in the south of China。深圳在中国的南部。 3、on

（1）on主要指“在……之上”，强调和表面接触： There is a book on the table。桌上有一本书。 （2）表示毗邻，接壤（是相邻关系）： Canada lies on the north of America 加拿大在美国的北边（与美国接壤）。 4、to 主要表示“在……范围外”，强调不接壤，不相邻。 Japan is to the east of China。日本在中国的东面。 注意： （1）at 强调“点”，on 强调“面”，in 强调“在里面”，to 表示“范围外”。 （2）on the tree：表示树上本身所长着的叶子、花、果实等 in the tree：表示某物或某人在树上 on the wall：表示在墙的表面，如图画、黑板等 in the wall：表示在墙的内部中，如门窗、钉子、洞、孔 5、above

介词in-on-at在表示时间时的用法

介词in, on, at在表示时间时的用法区别 ①in时间范围大（一天以上）如：in Tanuary, in winter, in 1999;泛指在上午，下午，晚上，如：in the morning(afternoon, evening). 习惯用法：in the daytime 在白天。 ②on指在某一天或某一天的上午，下午，晚上，如：on Monday, on Sunday afternoon, on July 1, 1999 ③at时间最短，一般表示点时间，如at six o’clock, at three thirty.习惯用法：at night, at noon, at this time of year. in, on和at在表达时间方面的区别 in 表示在某年、某季节、某月、某周、某天和某段时间 in a year在一年中 in spring 在春季 in September 在九月 in a week 在一周中 in the morning/afternoon/evening 在上午/下午/傍晚 但在中午，在夜晚则用at noon/night on 表示某一天或某一天的某段时间 on Monday 在周一 on Monday afternoon 在周一下午 on March 7th 在3月7日 on March 7th, 1998. 在1998年3月7日 on the morning of March 7th, 1998. 在1998年3月7日上午

at 表示某个具体时刻。 at eight o’clock 在8点钟 at this time of the year 在一年中的这个时候 at the moment 在那一时刻 at that time 在那时 注意：在英语中，如果时间名词前用this, last, next 等修饰时，像这样的表示，“在某时”的时间短语前，并不需要任何介词。 例如：last month, last week, this year, this week, next year, the next day, the next year 等。 1．What’s the weather like in spring/summer/autumn/winter in your country? 你们国家春天/夏天/秋天/冬天的天气怎么样？ in 在年、月、周较长时间内 in a week 在里面 in the room 用某种语言 in English 穿着 in red on 某日、某日的上下午on Sunday afternoon 在……上面 on the desk 靠吃……为生live on rice 关于 a book on Physics 〔误〕We got to the top of the mountain in daybreak. 〔正〕We got to the top of the mountain at day break. 〔析〕at用于具体时刻之前，如：sunrise, midday, noon, sunset, midnight, night。〔误〕Don't sleep at daytime 〔正〕Don't sleep in daytime. 〔析〕in 要用于较长的一段时间之内，如：in the morning / afternoon, 或in the week / month / year. 或in spring / supper /autumn / winter等等。 〔误〕We visited the old man in Sunday afternoon. 〔正〕We visited the old man on Sunday afternoon. 〔析〕in the morning, in the afternoon 如果在这两个短语中加入任何修饰词其前面的介

介词的用法及习题

第七单元介词 我们经常在名词或名词短语、代词或动名词前用介词表示人物、事件等与其它句子成分的关系。介词后面的名词或相当于名词的词语叫介词宾语。介词可表示地点、时间、比较、反对、原因、手段、所属、条件、让步、关于、对于、根据等。 二、介词的意义 1．表示时间的介词 in表示“在某一时间段”，或“在……某一时候”，如用在月、季、年份、时代、世纪等时间名词的前面，或用来泛指一天的某一段时间。 In July/summer/2000/ancient times/the 1999’s In the morning/afternoon/evening In也可以指“在……之后”，表示从说话起的若干时间内，如： The bus will be here in ten minutes. On表示“在特定的某一天”，也可用于带有修饰语的一天的某个时间段之前。如： on Saturday, on Saturday morning, on the morning of August 1st at表示“在某一时间点”，或用来表示不确定的时间和短期的假日、时节等。如： at six o’clock, at Easter 介词over, through (out)两者均指“经过的全部时间”。 Stay over the Christmas. 介词for, since for表示动作或状态延续的全部时间长度，为“长达……”之意；since用于指从过去特定的某个时刻到说话时为止的一段时间；两者往往用于完成时。 I have been there for six years. We have not seen each other since 1993. During指“在……时期/时间内”，必须以表示一段时间的词或词组作宾语。 She was ill for a week, and during that week she ate little. 2．表示地点的介词 介词at指小地点或集会场合；on表示线或面上的位置；in表示在立体、区域或环境内，特别是那些教大，能够容纳相应事物的环境。 He works at Peking University. Your radio is on the desk. The boat is in the lake. 3．表示原因的介词 for常常表示褒贬、奖惩的原因或心理原因。 4．表示目的的介词 for表示拟定的接收人或目的；to表示实际的接收人或目的。 I bought the gift for my little sister. I gave the gift to my little sister. 5．表示“关于……”的介词 一般about用于比较随便的谈话或非正式的文体；on用于正式的讲话、著作或报告中；7．表示价格的介词 at和for都可表示价格，at仅表示价格，for还表示“交换”，如： Eggs are sold at 95 cents a dozen here. I bought it for five pounds.

时间地点介词的用法

具体日期前用“on” 注意: 一、含有this, that, these, those, every, each 等的时间状语前不用介词。如： We are going to play football this afternoon. 今天下午我们打算踢足球。 His father goes to work early every day. 他爸爸每天很早去上班。They are working on the farm at the moment. 这几天他们正在农场干活。 二、all day, all week, all year 等由“all +表示时间的名词”构成的时间状语前不用介词。如： We stay at home and watch TV all day.我们整天呆在家里看电视。 三、由“some, any, one等＋表示时间的名词”构成的时间状语前不用介词。如： We can go to the Great Wall some day. 有一天我们会去长城的。 四、时间状语是today, tomorrow, tomorrow morning, tomorrow afternoon, tomorrow evening, the day after tomorrow (后天)等，其前不用介词。如：

What day is it today?今天星期几？ Who's on duty tomorrow? 明天谁值日？ MORE: at 表示时间的某一点 （节日或年龄、瞬间或短暂的时间） Your memory is always poor at this time. （表示一天中的某个时刻不用冠词） I got up at six in the mopning. on 表示某日或和某日连用的某个时间段 You were late on Monday last week. in 用于表示除日以外的某一时间段 （表示年、月、季节、世纪时代） Sorry, I am late, the frist time in May. in和at都可表示地点，而in表示的地点比at所表示的地点大

inonat的时间用法和地点用法版

精心整理in，on，at的时间用法和地点用法 一、in,on,at的时间用法 1、固定短语： inthemorning/afternoon/evening在早晨/下午/傍晚, 2 （on thenextmonth第二个月（以过去为起点的第二个月，nextmonth以现在为起点的下个月） everyday每天 onemorning一天早晨 yesterdayafternoon昨天下午

tomorrowmorning明天早晨 allday/morning/night整天/整个早晨/整晚（等于thewholeday/morning/night）mostofthetime（在）大多数时间 3、一般规则 除了前两点特殊用法之外，其他≤一天，用on，＞一天用in，在具体时刻或在某时用at（不强调时间范围） 关于 On 1 2) 3) （注意：节日里有表人的词汇先复数再加s’所有格，如 onChildren’sDay,onWomen’sDay,onTeachers’Day有四个节日强调单数之意思，onMother’sDay,onFather’sDay,onAprilFool’sDay,onValentine’sDay） 星期、onSunday在周日，onSundaymorning在周日早晨onthelastFridayofeachmonth在每个月的最后一个星期五

日期、onJune2nd在六月二日 onthesecond(ofJune2nd)在六月的第二天即在六月二日onthemorningofJune2nd在六月二日的早晨，onarainymorning在一个多雨的早晨 onacertainday在某天 onthesecondday在第二天（以过去某天为参照） 关于 In 1 2) InJune在六月 inJune,2010在2010年六月 in2010在2010年 inamonth/year在一个月/年里（在将来时里翻译成一个月/年之后） inspring在春天

inonat的时间用法和地点用法版

i n o n a t的时间用法和 地点用法版 集团档案编码：[YTTR-YTPT28-YTNTL98-UYTYNN08]

i n，o n，a t的时间用法和地点用法 一、in,on,at的时间用法 1、固定短语： inthemorning/afternoon/evening在早晨/下午/傍晚, atnoon/night在中午/夜晚,（不强调范围，强调的话用duringthenight）earlyinthemorning=intheearlymorning在大清早， lateatnight在深夜 ontheweekend在周末（英式用attheweekend在周末，atweekends每逢周末）onweekdays/weekends在工作日/周末， onschooldays/nights在上学日/上学的当天晚上， 2、不加介词 this,that,last,next,every,one,yesterday,today,tomorrow,tonight，all，most等之前一般不加介词。如， thismorning今天早晨 （on）thatday在那天（thatday更常用些） lastweek上周 nextyear明年 thenextmonth第二个月（以过去为起点的第二个月，nextmonth以现在为起点的下个月） everyday每天 onemorning一天早晨 yesterdayafternoon昨天下午 tomorrowmorning明天早晨

allday/morning/night整天/整个早晨/整晚（等于 thewholeday/morning/night） mostofthetime（在）大多数时间 3、一般规则 除了前两点特殊用法之外，其他≤一天，用on，＞一天用in，在具体时刻或在某时用at（不强调时间范围） 关于on On指时间表示： 1）具体的时日和一个特定的时间，如某日，某节日，星期几等。Hewillcometomeetusonourarrival. OnMay4th(OnSunday,OnNewYear’sday,OnChristmasDay),therewillbeacelebra tion. 2)在某个特定的早晨，下午或晚上。 Hearrivedat10o’clocko nthenightofthe5th. Hediedontheeveofvictory. 3)准时，按时。 Iftherainshouldbeontime,Ishouldreachhomebeforedark. 生日、onmyninthbirthday在我九岁生日那天 节日、onTeachers’Day在教师节 （注意：节日里有表人的词汇先复数再加s’所有格，如 onChildren’sDay,onWomen’sDay,onTeachers’Day有四个节日强调单数之意思， onMother’sDay,onFather’sDay,onAprilFool’sDay,onValentine’sDay）星期、onSunday在周日，onSundaymorning在周日早晨

介词in on at的用法归纳-1

介词in on at 的用法 1.介词at表时间、表地点。 （1）at表示时间，用于钟点前，用于时刻前，译为“在......时（刻）”。如： at three／three o'clock 在三点。 at a quarter to six 六点差一刻。 at noon 在中午，at night 在夜晚，at midnight 在半夜 at breakfast／lunch／supper 在吃早饭／午饭／晚饭时 at this time of day 在每天这个时候 （2）at表示地点，一般用于较小的地名（方）前，译为“在......”。如： at home 在家 at the station 在车站 （3）at表示处于......状态，译为“从事于......”。如： at school 在上学 at work 在工作 at加名词一般可与现在进行时态互换使用，表示正在进行的动作，试比较：They are at work．／They are working． 2．小小介词in，用途却很多。可表时间，表地点，表手段、方法、材料。 （1）in表示时间，用于泛指一天的上午、下午、晚上等；用于某个较长的时间，如年、月、季节等。如： in the morning／afternoon／evening在上（下午）或晚上，in 2003在2003年，in the day／daytime在白天 in还可以表示“从现在起一段时间以后”。如： They will see you in a week．他们将在一周后去看你。 另外，in和at都可以表示时间，但in表示较长的时间，而at表示时间的某一点。例如： He got up late in the morning and had a meal at noon．他早上起得晚，所以只吃午餐。 （2）in表示地点、场所，译为“在......里”、“在......中”。如： in the factory 在工厂 in the room 在房间里 in the sun 在阳光下 in the middle of...在......的中央 in和at都可表示地点，而in表示的地点比at所表示的地点大。 （3）in表示用语言，用......材料。译为“用......，以......方式”。如：in English用英语，in ink用墨水 （4）in表示穿戴的状态，译为“戴着、穿着”。如：in the white shirt穿着白色的衬衫，in the cap戴着帽子 【相关链接】in表示“穿（戴）着”是介词，指状态，同wear一样。in后接表示服装类的名词或表示颜色的词。如： Kate is in a red skirt．／Kate wears a red skirt．凯特穿着红裙子。 3．介词on表示时间、地点、方位等。 （1）on表示时间，用于星期、日期（包括该天的各部分）。如：on Sunday／Sundays，on Monday morning／afternoon／evening等。 on也用于某一日的名词前，用于公共节假日前。如：