Classi?cation of networks based on inherent
structural characteristics
Tajudeen H.Sikiru?,Adisa A.Jimoh?,Yskandar Hamam?,John T.Agee?and Roger Ceschi§
?Department of Electrical Engineering,Tshwane University of Technology,South Africa and LISV of UVSQ,France.
Email:sikiruth@tut.ac.za
?Department of Electrical Engineering,Tshwane University of Technology,South Africa.
Email:jimohaa@tut.ac.za;ageejt@tut.ac.za
?ESIEE Paris,France and FSATI at Tshwane University of Technology,South Africa.
Email:hamama@tut.ac.za
§LISV of UVSQ and ESME Sudria,France.
Email:ceschi@esme.fr
Abstract—This paper seeks to identify and classify power system networks based on their inherent de?nitive structural property.The participation between the load buses is observable from the eigenvectors obtained from a Schur complement of the Y-admittance matrix.This is used to classify power system networks as either topologically strong or weak.Results show that in a topologically weak network,load voltages are below the nominal voltage limit.Conversely,in a topologically strong network they are above the nominal limit.
I.I NTRODUCTION
The main purpose of transmission networks is to convey power from generating stations to load centres.Every trans-mission network has unique characteristics arising from the manner in which lines are interconnected and the impedance values of such lines[1].It is important to identify the effect of these two factors on the operational behaviour of a power system network.Since,a transmission network cannot be loaded beyond its stability limit[2].The direct consequence is that transmission network determines the amount of power that could be transported from generating stations,even if the generating stations have higher supply capacity[3].Hence, the level of load demand that could be met in a power system network directly depends on the inherent structural characteristics[4]–[7]of the network.These characteristics do not only affect the amount of transferable power,it also determines the locations and sizes of the other network devices such as reactive power compensators[6],harmonic?lters[5], and new generator location[7]that could boost the operational ef?ciency of a network.
This paper discusses the identi?cation and classi?cation of power system networks based on their structural character-istics.For the remainder of the paper,section II presents the inherent structural characteristics and classi?cation of net-works,while section III presents and discusses two numerical examples.Section IV concludes the paper.
II.I NHERENT STRUCTURAL CHARACTERISTICS AND
CLASSIFICATION OF NETWORKS
A.The inherent structural characteristics of networks Power system operations are represented by two variable quantities,current and voltage,which are interrelated through the network structure called the Y-admittance matrix.The Y-admittance matrix captures the nature of the structural interconnection of buses and the value of the line impedance between them[6],[7].The current?ow in the network and the bus voltages are governed by circuit theorem,mathematically represented as
I=Y V(1) where Y?1=Z,Y is admittance,while Z is the impedance of the network.
Suppose the Y-admittance matrix is partitioned as
Y=
Y GG Y GL
Y LG Y LL
(2)
where the Y-admittance matrix is a square matrix with dimension(G+L)×(G+L),Y GG is a square matrix of dimension G×G containing the connectivity to generator buses.Y GL is a G×L matrix relating the generator to load buses.Y LG is the transpose of Y GL.Y LL is a square matrix of dimension L×L containing the connectivity to load buses.
G is the number of generator buses and L is the number of load buses in the network respectively.
The matrix Y GG is a diagonally dominant matrix[8]since the diagonal elements of this matrix are
|a ii|≥
G
j=1
j=i
|a ij|for all i=1,2,···,G(3)
Due to this property,matrix Y GG is non-singular and invertible[8],[9].
978-1-4673-2673-5/12/$31.00c 2012IEEE
Therefore,the Schur complement[10],[11]of Y GG in Y from(2)is
C LL=Y LL?Y LG Y?1
GG
Y GL(4) The relationship between this Schur complement[10]and the Y-admittance matrix is
det Y=det Y GG det C LL(5) Matrix C LL is equivalent to the load admittance matrix where the in?uence of generator buses has been eliminated.It contains only structural characteristics of load buses.
Since generators are the sources of active power in a network, generator voltages are presumed constant and known,because they are easily controllable.The voltages of interest and the most critical are those of load voltages in power system analysis[1].The relationship between the load structural characteristics and the load voltages becomes obvious from expanding(1)as
I G I L
=
Y GG Y GL
Y LG Y LL
V G
V L
(6)
The algebraic manipulation of(6)gives
[V L]=[C LL]?1[I L?W LG I G](7)
Where W LG=Y LG Y?1
GG .
The load structural characteristics(C LL)is inversely related to the load voltages as shown by(7).The effect of the structural interconnection between load buses and the network load voltages could only become clearer by quantifying the structural impact of the load buses on the load voltages.To achieve this,the eigenvalue decomposition[12]is used to analyze the structural impact of the load buses as
C LL=MRM?=
n
i=1
m iμi m?i(8)
Where M is an orthonormal matrix with corresponding m i eigenvectors.The diagonal matrix R has the eigenvaluesμi as its diagonal elements.The inverse of matrix C LL is
C?1 LL =MR?1M?=
n
i=1
m i m?i
μi
(9)
Substituting(9)into(7)yields
[V L]=[n
i=1m i m?i
μi
][I L?W LG I G](10)
The effect of the interconnectivity and line impedance values between load buses and their effect on the overall load voltages are revealed in(10)through the reciprocal relationship be-tween the bus eigenvalues and the bus voltages.Buses associ-ated with the smallest eigenvalues have the most contributively effect on the load voltages based on the reciprocal relationship presented in(10).B.Classi?cation of networks
Line impedance is made up of resistive and reactive components.The reactive component of transmission lines contributes to the reactive power?ow in the network[13]. Reactive component may consist of inductive and capacitive properties.The voltages at the load buses depend on the ade-quacy of reactive power in the network.Transmission networks with suf?cient reactive property may have bus voltages above the nominal voltage limit of 1.0p.u.On the other hand, shortage of this property may cause the bus voltages to be below the nominal voltage limit[14].In an ideal network, where there is adequate reactive element in the network and the total impedances of the transmission network and the load are exactly matched,the voltages on all the buses will be at1.0 p.u(the nominal voltage value)[1].However,in reality this is not achievable because of environmental factors that limit the expansion of the network,scarce resources and unforeseen load growth.The best structural design of a network that could be hoped for is the one that allows the load voltages to be within reasonable range in respect to the nominal voltage limit. Depending on the topological structure of a network and its line impedances,a network acquires certain de?nitive property that determines voltages at the load buses.Since,load voltages are not allowed to deviate signi?cantly from the nominal value because of power quality and stability issues,the total impedance of loads in a network must be matched with that of the transmission network for maximum power to be transferable to the load[15].The satisfaction of this circuit theorem condition,limits the maximum loading a transmission network can support.Thus,the de?nitive property a network acquires based on its topological structure is unique.As such, a network could have its load voltages to be generally above the nominal limit,which we termed topological strong network or below the nominal limit,which we de?ne as topologically weak network.As load increases or reduces in a network,the effect is a corresponding reduction or increase in load voltages. However,a network will retain its de?nitive property except there is a signi?cant change in the network topology.Hence,a network that is topologically strong or weak will still exhibit the same characteristics despite a small variation in loading, since the impedances of the transmission network and load are expected to be matched to ensure operational ef?ciency of the network.This de?nitive property is inherent in all power system networks.
The structural characteristics of load buses captured by the matrix C LL could be used to determine the de?nitive property of networks,since each bus is associated with an eigenvalue based on the electrical distance between the load buses.The association of a unique eigenvector to a load bus corresponding to the smallest eigenvalue,we have termed the“participation between load buses”.For a network where the buses are far away from one another,the absolute value of the smallest eigenvalue will be zero(i.e.|μn|=0to a precision of10?4). This indicates a network with less reactive element and con-sequently less reactive power support.The eigenvectors(m i)
corresponding to the smallest eigenvalue will have the same value,indicating the non-participation electromagnetically be-tween the buses.This characteristic is typical of topologically weak networks.On the other hand,when the absolute value of the smallest eigenvalue is greater than zero(i.e.|μn|>0to a precision of10?4),the corresponding absolute eigenvectors will have different values.This characterised a topologically strong network,where the electrical distance between load buses is small.
The next section presents two numerical examples,one each for topologically weak and strong network respectively.
III.N UMERICAL EXAMPLES AND DISCUSSION
A.IEEE30bus network
The?rst numerical example to be considered in this section is the IEEE30bus network.The single line diagram is shown in Fig.1.
The absolute value of the smallest eigenvalue for this test network is less than the precision de?ned,hence it is zero,the corresponding eigenvectors associated with this eigenvalue are the same as shown in Fig.2.
The unchanging nature of the eigenvectors associated with the load buses shows the non-participation between these buses as presented in Fig.2.This is due to the large electrical distances between the load buses as captured by the Y-admittance matrix.The data required to build the Y-admittance matrix for this test network are shown in the appendix.The non-participation between the load buses and the fact that the smallest eigenvalue is zero,indicate that this test network is a topologically weak network.As such,its load bus voltages are expected to be generally below the nominal limit of1.0p.u. Fig.3shows the voltage pro?le for this test network and all the load voltages are well below the nominal limit.
In order to illustrate the non-effect of loading on the unique de?nitive property of a network,which is indeed inherent to a network due to its topological characteristics,a50%reduction in loading at all the buses was carried out;the new network bus voltages are shown in Fig.3.Even with a50%reduction in total loading of the network,the bus voltages are all still below the nominal voltage limit.This network is indeed a topologically weak network.
B.Southwest40bus network
In the case of the second numerical example,we will consider the Southwest England40bus network.The single line diagram for this network is shown in Fig.4.The smallest eigenvalue(in absolute value)is greater that the precision de?ned for this test network and it is0.0045.The eigenvectors corresponding to this smallest eigenvalue is shown in Fig.5. The eigenvectors associated with each load buses have varying numerical values as seen in Fig.5and hence unique for each load bus.This property arises from the small electrical distances between the load buses and the strong structural tie between them.The transmission network data for this test network are shown in the appendix.
The varying numerical values of each eigenvector
indicates
Fig.1.IEEE30bus
network
Fig.2.Eigenvectors corresponding to the smallest eigenvalue of IEEE30 bus
network
Fig.3.V oltage pro?les of IEEE30bus network
Fig.4.
Southwest England 40bus
network
Fig. 5.Eigenvectors corresponding to the smallest eigenvalue for the Southwest England 40bus network
that this test network is a topologically strong network.The voltage pro?les of the network at 100%loading are shown in Fig.6and are above the nominal voltage limit.A 50%increase in loading level shows that a couple of voltages are still above the nominal voltage limit of 1.0p.u,even for such a high increase in loading level.This test network is indeed topologically strong to carry such a level of loading and still have a couple of voltages above the nominal limit.
The advantages of having a simple approach of classifying network are twofold.Firstly,in the planning phase of a net-work,the behavioural characteristics of each proposed design for a network may be quickly compared without running repetitive load ?ow studies.This advantage comes handy for a relatively large network,where many alternative paths for connecting load buses may need to be evaluated before a suitable design is selected.Secondly,during the operational phase of a network,it may be necessary to improve the functionality of a network due to expansion constraints.In this case,the locations of network devices that could improve
the
Fig.6.
V oltage pro?les of Southwest England 40bus network
operational ef?ciency of the network could be more effective,if the structural characteristics of the network are taking into consideration in locating these devices.
IV.C ONCLUSION
This paper has demonstrated the identi?cation and classi?-cation of power system networks using the de?nitive structural property of the network.Power system networks are broadly classi?ed into topologically strong or weak networks.Topolog-ically strong networks have load voltages above the nominal voltage limit,whereas topologically weak networks have load voltages below this limit.These classi?cations are based on the participation of load buses observable from the eigenvectors of a Schur complement of the Y-admittance matrix termed the structural characteristics impact of load buses.
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A PPENDIX
In this section,the transmission network parameters for IEEE30and Southwest England40bus networks are shown in the tables below.
TABLE I
T RANSMISSION LINE PARAMETERS FOR IEEE30BUS NETWORK
S/N From To R(p.u)X(p.u)
1170.04520.1852
2120.01920.0575
31190.01690.0599
41140.6360.2
513120.00550.11
614120.09360.209
715120.03240.0845
816130.03480.0749
917130.07270.1499
1017160.01160.0236
1119180.12310.2559
1220180.06620.1304
13820.0570.1737
1421180.09450.1987
1520190.2210.1997
1622200.1070.2185
1723200.10.202
1815210.08240.1932
1924220.06390.1292
2014240.0340.068
2125170.1150.179
TABLE II
T RANSMISSION LINE PARAMETERS FOR IEEE30BUS NETWORK
CONTINUED
S/N From To R(p.u)X(p.u)
2225230.1320.27
2326250.18850.3292
24870.01320.0379
2527260.25440.38
2628260.10390.2087
2729280.21980.4153
2830280.32020.6027
2930290.23990.4533
305120.0140.208
316180.0070.14
32320.04720.1983
33920.05810.1763
341030.0460.116
35980.01190.0414
361090.02670.082
37490.0120.042
Transformers parameters
381290.01040.208
391390.02780.556
401880.01280.256
4128110.01980.396
TABLE III
L INE PARAMETERS FOR S OUTHWEST E NGLAND40BUS NETWORK S/N From To R(p.u)X(p.u)B(p.u)
125260.0006170.0084320.35012
225260.0006170.0084320.3501
326390.0005230.007150.29655
426390.000520.007110.285
512150.0009360.0074480.22967
612150.0009360.0074480.22967
717210.000350.0241460.058978
812250.0007790.0106480.4421
912250.0007790.0106480.4421
10170.004090.0340820.96111
11350.001180.0098320.2772
1224160.0005230.007130.7547
1324160.0005230.007130.7547
14450.0011730.0097760.27568
15323100.0346410
16323600.10380
1723170.0020770.0165360.5098
1821280.0009430.0075710.11711
1919270.0009440.007590.12472
201190.0011220.0153320.63657
21373600.0222550
22750.0009180.0073050.22515
238170.0006410.0051020.15718
TABLE IV
L INE PARAMETERS FOR S OUTHWEST E NGLAND40BUS NETWORK
CONTINUED
S/N From To R(p.u)X(p.u)B(p.u)
2415160.0002110.0028850.11979
25310.0022840.0183980.5546
26850.0009180.0073050.22515
2738120.003060.0039640.7604
2838140.0002460.0033620.13961
2916230.0019640.0156280.48192
3016230.0019640.01562890.48192
31313000.079060
3217190.000350.0241460.058978
331050.0009090.0121230.50235
3414120.0004830.0065980.27397
3511100.0006450.0088210.36627
36590.0004360.0059560.2473
3717180.0001150.010550
38240.0011060.0090190.26562
3923170.0020770.0105360.5098
4011120.0009630.0131570.54617
41180.004090.0340820.96111
427170.0006410.0051020.15718
43210.0011730.0093380.28787
4411380.0007280.0099510.4129
45302900.117210
4615160.0002110.0028850.11979
TABLE V
T RANSFORMER PARAMETERS FOR S OUTHWEST E NGLAND40BUS
NETWORK
S/N From To R(p.u)X(p.u)
15320.0017430.083041
25320.0017430.083041
327370.0018590.08
49350.000750.0388
534110.00040.02056
637280.0016970.080875
710330.000730.0412
88360.0014580.080458
93130.0016280.084166
103020.0018090.08
113020.0014730.079666
122910.0014180.083418
132910.001230.079708
143140.0016140.083541
15131200.033333
1640380.0001080.006375
1720190.002050.0805
1822210.002050.0805
195600.033333
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：
表示地点的介词 in、on、behind、next to、near、over、under (1) in在……里面：The pencil is in the desk. 铅笔在课桌里。 (2) on在……上面：There are some apple on the tree. 树上有些苹果。 (3) under在……下面/正下方：What's under your desk? 你书桌底下是什么？ (4) over在……正上方：There is a shelf over the table. 桌子上方有一个书架。 (5) above 在……斜上方：Raise your arms above your head. (6) below 在……斜下方：Her skirt came below her knees. (7) behind在……之后：There is a bike behind the tree. 树后有一辆自行车。 (8) next to在……旁边：There is a shop next to the school. 理发店隔壁是一家咖啡馆。 (9) near在……附近：My bed is near the window. 我的床在窗户旁。 (10) by在……旁：He was sitting by the window. (11) beside 在旁边He sits down beside Jim. 一组：over, above和on的用法 1) over指在…的正上方，表示垂直在上。如 There is a lamp over the desk. 2) above指在上方，属于斜上方。如： Raise your arms above your head. 3) on指在上面，表示两物体接触。如： There is a cup on the table. 二组：under / below的用法： 1) under在……下面/正下方： What's under your desk? 2) below 在……斜下方： Her skirt came below her knees 三组：in 和on表示“在……上” 1)门/窗一类——镶嵌在墙里的，用in; 2)字画一类——挂/贴在墙面上的，用on ( ) 1 He put up a map ___ the back wall because there was a hole ______ it. A. on; on B. at; in C. on; in D. on; at ( ) 2 There is a door___ the wall. A. on B. to C. of D.in 3)人/鸟其他东西在树上，用in; 4)枝叶果实长在树上的，用on ( ) 1 There are some birds singing___ the trees. A. in B. on C. at D. from ( ) 2 There are so many apples___ that tree. A.in B, on C of D.from
龙源期刊网 https://www.doczj.com/doc/3f19059313.html, 浅析《诗经》中的方位词“南”及其文化内涵作者：王春艳 来源：《汉字文化(教育科研卷)》2018年第07期 【提要】本文就《诗经》中出现频率较多的方位词“南”进行辨析，并对具有代表性的“南方”“南亩”“南山”进行具体分析，由此我们可知“南”这一方位词，有着温暖和煦、丰年祈福之愿，有着少妇思君、忧心忡忡之情。随着对“南”与长养、情思、尊愿等方面的分析，可见方位词“南”的文化内涵不断深化并影响深远。通过对方位词“南”的探析，我们可以加深对《诗经》的认识，从而揭开遥远先秦的神秘面纱。 【关键词】诗经方位词“南” 文化内涵 《诗经》作为先秦人民真实的生活写照，其所包含的先民思想、风俗习惯、地理方位等都是我们了解先秦人民生活风貌的重要载体。关于《诗经》中方位词“南”，此前已有学者对此进行研究，譬如张德鑫的《方位词的文化考察》，方经民的《汉语空间方位参照的认知结构经过统计》，金安辉的《诗经》中的“东、西、南、北”及其对后世诗歌的影响等，笔者在前人研究的基础上，旨在更加具体、深刻地分析方位词“南”及其文化内涵。据统计，《诗经》中“南”出现了81次，那么《诗经》中的“南”是仅指方向的方位词呢，还是有着特殊的文化内涵？文化内涵也可以说是文化义，周一农的《词汇的文化蕴涵》中指出“文化义，指的是词在特定文化背景下所获得的反映一个名族风俗习惯、文化背景、宗教信仰和思维方式等诸多文化因素的隐含义”。①因此方位词的文化内涵就是对这些文化因素的分析。下面我们将对《诗经》中的方位词“南”进行逐步探讨，从而还其完整面貌。 一、“南”与长养 万事万物皆有源头，那么方位词源于何处？先秦人民不像现代人一样可以用多种方式指认方向，他们最先感受到的是自身和空间的环境关系，“日出而作，日落而归”，四方就是根据太阳这一参照物来确定的。即太阳升起处定为东方，落下处定为西方，直照处定为南方，背阳处定为北方。这就是人们对方位最初的认识。而我们现在所说的方位词，更加术语化，其实还是指东、西、南、北等。 经统计，我们发现《诗经》中“南”多有表示南方的意思，《说文解字》：“南，木至南方而有枝任也”，即南方是夏天草木繁盛的象征。《诗经》中《周南·樛木》“南有樛木，葛藟累之”；《周南·漢广》“南有乔木，不可休思”；《召南·草虫》“陟彼南山，言采其蕨”这些例子不仅表明这些草木生长在南方，也进一步表明了南方的“樛木”“乔木”“蕨”是何其丰茂，这正如《白虎通·五行》中“南方主长养”的说法，又《黄帝内经·素问·异法方宜论》：“南方，天地所长养，阳之所盛处也”，所以南方是温暖和煦的，也是植物生长的好地方，是生命的象征。
介词in，on，to 表示方位的用法 介词 in，on，to 都可以用来表示某个位置的方向，它们的意义不同，故表示的方向及范围也不同： 1. in 表示方位，含义是“在……之内”，即一个小地方处在一个大地方的范围(疆域)之内。例如： China is in the east of Asia. 中国在亚洲东部。(中国是亚洲的一个国家，处于亚洲的范围之内) Guilin is in the north of Guangxi. 桂林在广西北部。(桂林是广西的一座城市) Taiwan lies in the east of China. 台湾在中国的东部。(台湾是中国东部的一个省份，是中国的领土，在中国的疆域之内) Shanghai lies in the east of China. 上海位于中国的东部。(上海是中国的一个行政区域，在中国的疆域之内) The plant can be seen only in the north of Canada. 那种植物只有在加拿大北部才看得到。(暗指这种植物只生长在加拿大北部地区) The sun rises in the east and sets in the west. 太阳东升西落。 说明：表示某个地方的地理位置时，be，lie 以及 be located 的意义是一样的，可以互换使用。 2. on 表示方位，含义是“在……端/边”，即一个地方在另一个地方的某一端或某一边，两个地方只是相邻或接壤，却互不管辖。例如： Guangdong Province is on the southeast of Guangxi. 广东省在广西的东南边。(广东省与广西在地理位置上是连在一起的，即两者相邻，却互不管辖) China faces the Pacific on the east. 中国东临太平洋。(中国与太平洋相邻) The country is bounded on the west by the sea.那个国家西边与海接界。(暗指该国为沿海国家) Sichuan Province is on the north of Guizhou Province. 四川省在贵州省的北边。(四川省与贵州省在地理上也是连在一起的，但互不管辖) 3. to 表示方位，含义是“在……面”，即一个地方在另一个地方的范围之外，互不管辖。尤其当两个地方相隔较远，且有湖泊、大海等区域相隔时，通常用 to。例如： Japan is to the east of China. 日本在中国的东面。(日本在中国范围之外，且有日本海分隔) Taiwan is to the southeast of Fujian Province. 台湾在福建省的东南面。(台湾在福建省的范围之外，且两者之间有台湾海峡分隔) Jinzhou is to the west of Shenyang. 锦州在沈阳的西面。(锦州和沈阳分别为两座城市，地理位置上互不
（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
表示地点和位置的介词 1.at, in, on 1) at 表示较狭窄较小的地方（小村庄，小城镇），in 表示较大的地方（大城市，大的空间）。 I met her at the bus-stop. They arrived at the famous town in South Jiangsu. She is living in Nanjing. There are a great many islands in the Pacific. 2) 门牌号码前用at，road前面用on，street前用in或on。 in the street (BrE) on the street (AmE) at 103 Wall Street on the road 3) 把某个机构看成是机关或组织时用at，看成一个具体的地方时用in She is at Oxford. 她在牛津读书。She is in Oxford 她在牛津居住（工作或逗留） 4）at可以表示有意、有目的的行为。 She is at the table. 她在吃饭She is beside/ by the desk. 她坐在桌旁。 5) on 在---上面，表示上下两者紧贴在一起，in 表示在---里面。 She put the book on the desk. She put the book in the desk. She wore a smile on her face. (面部表情) She was wounded in the face. （伤有深度） 2．on 和underneath underneath 是on的反义词，表示某物紧贴在另一物的底下 There is a piece of paper underneath the dictionary. 3.under 和over under 和over 是一对反义词，表示正上方，正下方，没有接触的含义。 There are some chairs under the tree. The lamp hung over the table. under 和over 还可以表示上级、下级。 He is over us= We are under him. 4. above 和below 两者是一对反义词，表示高于、低于，既不表示接触，也不表示上下垂直。 The plane is flying above us. The sun has sunk below the horizon. 5. beneath 可以和underneath, under, below 互换。 6．at, by, beside at 表示有目的的接近、接触，by和beside 表示偶然的接近，不接触。 She will be waiting for you at the school gate at 7 tomorrow. The girl stood by/ beside her mother. To those who stand by me, I shall stand by my promise. 对那些支持我的人，我将恪守诺言。 7．near 和next to Near 表示在---附近，靠近；next to 表示紧挨着，紧靠着。 No birds or animals came near the lake. She went and sat next to him. 8. before, in front of, at the front of, ahead of before 用于某人前；in front of 用于建筑物前；in front of 和ahead of 用于空间可互换，用于时间只能用ahead of；in the front of 表示内部空间的前部；at the front of 表示外部空间
常用标点符号用法简表 标点符号栏目对每一种汉语标点符号都有详细分析，下表中未完全添加链接，请需要的同学或朋友到该栏目查询。名称符号用法说明举例句号。表示一句话完了之后的停顿。中国共产党是全中国人民的领导核心。逗号，表示一句话中间的停顿。全世界各国人民的正义斗争，都是互相支持的。顿号、表示句中并列的词或词组之间的停顿。能源是发展农业、工业、国防、科学技术和提高人民生活的重要物质基础。分号；表示一句话中并列分句之间的停顿。不批判唯心论，就不能发展唯物论；不批判形而上学，就不能发展唯物辩证法。冒号：用以提示下文。马克思主义哲学告诉我们：正确的认识来源于社会实践。问号？用在问句之后。是谁创造了人类？是我们劳动群众。感情号①！1.表示强烈的感情。2.表示感叹句末尾的停顿。战无不胜的马克思主义、列宁主义、毛泽东思想万岁！引号 ②“ ” ‘ ’ ╗╚ ┐└1.表示引用的部分。毛泽东同志在《论十大关系》一文中说：“我们要调动一切直接的和间接的力量，为把我国建设成为一个强大的社会主义国家而奋斗。”2.表示特定的称谓或需要着重指出的部分。他们当中许多人是身体好、学习好、工作好的“三好”学生。 3.表示讽刺或否定的意思。这伙政治骗子恬不知耻地自封为“理论家”。括号③（）表示文中注释的部分。这篇小说环境描写十分出色，它的描写（无论是野外，或是室内）处处与故事的发展扣得很紧。省略号④……表示文中省略的部分。这个县办工厂现在可以生产车床、电机、变压器、水泵、电线……上百种产品。破折号⑤——1.表示底下是解释、说明的部
分，有括号的作用。知识的问题是一个科学问题，来不得半点的虚伪和骄 傲，决定地需要的倒是其反面——诚实和谦逊的态度。2.表示意思的递进。 团结——批评和自我批评——团结3.表示意思的转折。很白很亮的一堆洋 钱！而且是他的——现在不见了！连接号⑥—1.表示时间、地点、数目等 的起止。抗日战争时期（1937-1945年）“北京—上海”直达快车2.表 示相关的人或事物的联系。亚洲—太平洋地区书名号⑦《》〈〉表示 书籍、文件、报刊、文章等的名称。《矛盾论》《中华人民共和国宪法》《人 民日报》《红旗》杂志《学习〈为人民服务〉》间隔号·1.表示月份和日期 之间的分界。一二·九运动2.表示某些民族人名中的音界。诺尔曼·白求 恩着重号.表示文中需要强调的部分。学习马克思列宁主义，要按照毛泽 东同志倡导的方法，理论联系实际。······
英语中表示时间、地点和位置的常用介词的应用 内容摘要：介词是一种用来表示词与词, 词与句之间的关系的词,在句中不能单独作句子成分。介词后面一般有名词代词或相当于名词的其他词类、短语或从句作它的宾语。介词在英语中有非常重要的地位,但其种类繁多,用法复杂,一个介词还往往有多种意义,本文将从时间、地点和用名词尤其是由动词转化过来的名词的机会较多,而名词与名词之间常常需要介词连接,故英语中使用介词的现象比比皆是。 关键词:表示时间地点和位置附加状语名词动词 内容： 一、英语中表示时间的常用介词 after表示...之后，指某事发生在所指时间后的任意时间，是before的反义词，表示在...之后（1）用在附加状语里，常跟有-ing小句，，如： Li Ming was released from prison after serving three years.李明在服刑三年后出狱。（2）用在名词之后，如：I hate the time after sunset before you come home.我不喜欢日落之后、你回家之前的这段时间。（3）用在动词be之后，如：He turned and went after his brothers.他转身去追赶他的兄弟们。after通常指次序的先后。 in（1）表示在某世纪、年、季度、月、周”以及泛指的上、下午、晚上。如：in the 20th century在20世纪；in 1999在1999年；in winter在冬季；in September在九月；in the morning/afternoon/evening 在上午/下午/晚上。（2）in 过...后(未来时间)，不晚于，如：The train will arrive in three hours.火车三小时到。（3）表示某段时间之后，如：to return in a few minutes/hours/days/months几分钟/几小时/几天/几个月后回来。（4）表示做...时，...发生时，当...时，如：In attempting to save the child from drowning, she nearly lost her own life.她在抢救落水儿童时，自己差点丧命。 注：after与in都可表示“在……之后”，但after后可跟时间段，也可跟时间点；而in后必须跟时间段。after既可用于将来时，也可用于过去时，而in只能用于将来时。I’ll arrive in an hour. 我一小时后到。 during表示在……期间(1)某事在某段时间里连续发生或发生过几次，用在附加状语里，如：During all the years of work, he had been realistic with himself.这些年来在所有的工作中，他总是对自己实事求是。（2）表示某物在某段时间里从开始到结束，都一直得到发展，用在附加状语里，如:I hope this will become clear to you during the course of the lectures.我希望在讲座过程中，你会渐渐明白这一点。（3）指某事在某一期间内的某一刻发生，用在附加状语里，如：The boy disappeared from the hotel during the night.这名男孩在夜间从旅馆失踪。 from表示时间的起点，从……起，多用于“from…to/till…”中。如：You can come anytime from Monday to Friday. 周一至周五你什么时间来都行。from 仅说明什么时候开始，不说明某动作或情况持续多久。 for 表示达...之久（1）过了多少时间，后接“一段时间”，表示某事持续多久，多与完成时连用，如：She has been ill for several days. 她已经病了几天了。（2）表示某事已经发生过一次，用在附加状语里，如：Before using a pan for the first time, wash it with a sponge.在首次使用平底锅前，用
一、基本定义 句子，前后都有停顿，并带有一定的句调，表示相对完整的意义。句子前后或中间的停顿，在口头语言中，表现出来就是时间间隔，在书面语言中，就用标点符号来表示。一般来说，汉语中的句子分以下几种： 陈述句： 用来说明事实的句子。 祈使句： 用来要求听话人做某件事情的句子。 疑问句： 用来提出问题的句子。 感叹句： 用来抒发某种强烈感情的句子。 复句、分句： 意思上有密切联系的小句子组织在一起构成一个大句子。这样的大句子叫复句，复句中的每个小句子叫分句。 构成句子的语言单位是词语，即词和短语（词组）。词即最小的能独立运用的语言单位。短语，即由两个或两个以上的词按一定的语法规则组成的表达一定意义的语言单位，也叫词组。 标点符号是书面语言的有机组成部分，是书面语言不可缺少的辅助工具。它帮助人们确切地表达思想感情和理解书面语言。 二、用法简表 名称
句号① 问号符号用法说明。？1．用于陈述句的末尾。 2．用于语气舒缓的祈使句末尾。 1．用于疑问句的末尾。 2．用于反问句的末尾。 1．用于感叹句的末尾。 叹号！ 2．用于语气强烈的祈使句末尾。 3．用于语气强烈的反问句末尾。举例 xx是xx的首都。 请您稍等一下。 他叫什么名字？ 难道你不了解我吗？为祖国的繁荣昌盛而奋斗！停止射击！ 我哪里比得上他呀！ 1．句子内部主语与谓语之间如需停顿，用逗号。我们看得见的星星，绝大多数是恒星。 2．句子内部动词与宾语之间如需停顿，用逗号。应该看到，科学需要一个人贡献出毕生的精力。 3．句子内部状语后边如需停顿，用逗号。对于这个城市，他并不陌生。 4．复句内各分句之间的停顿，除了有时要用分号据说苏州园林有一百多处，我到过的不外，都要用逗号。过十多处。 顿号、用于句子内部并列词语之间的停顿。
Montrer et situer les objets 1.Les mots pour situer les objets. a.contre对着，朝着 b. sur 在…上空 c. a droite (de)在…右边 d. a gauche (de)在…左边 e. sous 在…下面 f. dans在…里面 g. a cote (de)在…旁边h. derriere在…后面i. devant 在…前面 j. au-dessus 在…上方k. au-dessous 在…下方l. entre 在…中间 m. en face de 在…对面n. au bout de 在…尽头o. pres de 在…附近 2.Les mots Cles. a.Vous arrivez 您到达 b. vous prenez 您乘 c. vous allez 您去 d. passez您经过 e. continuez 继续走 f. traversez 穿过 g. tournez 转弯h. entrez走进…i. tout droit 直走 https://www.doczj.com/doc/3f19059313.html, rue 那条路k. par la从那边 3.Transport. a. A pied 走路 b. avelo骑自行车 c. a moto 骑摩托车 d. en rollers滑旱冰 e. en bus 乘公交车 f. en metro乘地铁 g. en voiture 乘汽车h. en taxi乘出租车 -Comment y aller ? -C’est loin. -?a se trouve près d’ici. -C’est situé à 20km de Paris. -Je suis perdue. Je cherche la rueBotonnet pour aller.....vous pouvez m’indiquer....par où il faut passer pour aller à -C’est de quel c?té? Dans quelle direction ? -Continuez jusqu’à un café qui est au bout de la rue. -Vous suivez la Seine. -Vous traversez la rue et passez devant la poste. -C’est à 5 min à pied . -Vous prenez la première à gauche, tout droit.
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
表示地点位置的介词 w qsa 1)at ,in, on, to，for at (1)表示在小地方; (2)表示“在……附近，旁边”in (1)表示在大地方; (2)表示“在…范围之内”。on 表示毗邻，接壤，“在……上面”。to 表示在……范围外，不强调是否接壤；或“到……”2)above, over, on 在……上above 指在……上方,不强调是否垂直，与below相对；over指垂直的上方,与under 相对,但over与物体有一定的空间，不直接接触。on表示某物体上面并与之接触。The bird is flying above my head. There is a bridge over the river. He put his watch on the desk. 3)below, under 在……下面under表示在…正下方below表示在……下，不一定在正下方There is a cat under the table. Please write your name below the line. 4)in front [frant]of, in the front of在……前面in front of…意思是“在……前面”，指甲物在乙物之前，两者互不包括；其反义词是behind（在……的后面）。There are some flowers in front of the house.(房子前面有些花卉。) in the front of 意思是“在…..的前部”，即甲物在乙物的内部.反义词是at the back of…（在……范围内的后部）。There is a blackboard in the front of our classroom. 我们的教室前边有一块黑板。Our teacher stands in the front of the classroom. 我们的老师站在教室前.(老师在教室里) 5）beside，behind beside 表示在……旁边behind 表示在……后面 2.表示时间的介词 1)in , on，at 在……时in表示较长时间，如世纪、朝代、时代、年、季节、月及一般（非特指）的早、中、晚等。如in the 20th century, in the 1950s, in 1989, in summer, in January, in the morning, in one’s life , in one’s thirties等。on表示具体某一天及其早、中、晚。如on May 1st, on Monday, on New Year’s Day, on a cold night in January, on a fine morning, on Sunday afternoon等。at表示某一时刻或较短暂的时间，或泛指圣诞节，复活节等。如at 3:20, at this time of year, at the beginning of, at the end of …, at the age of …, at Christmas，at night, at noon, at this moment等。注意：在last, next, this, that, some, every 等词之前一律不用介词。如：We meet every day. 2)in, after 在……之后“in +段时间”表示将来的一段时间以后；“after+段时间”表示过去的一段时间以后；“after+将来的时间点”表示将来的某一时刻以后。3)from, since 自从……from 仅说明什么时候开始，不说明某动作或情况持续多久；since表示某动作或情况持续至说话时刻，通常与完成时连用。since表示"自（某具体时间）以来"，常用作完成时态谓语的时间状语。since liberation（1980）自从解放（1980年）以来They have been close friends since childhood．他们从小就是好朋友。（1）since the war是指"自从战争结束以来"，若指"自从战争开始以来"，须说"since the beginning of the war"。（2）不要将since与after混淆。比较：He has worked here since 1965．（指一段时间，强调时间段）自从1965年以来，他一直在这儿工作。He began to work here after 1965．（指一点时间，强调时间点）从1965年以后，他开始在这儿工作。4)after, behind 在……之后after主要用于表示时间；behind主要用于表示位置。时间名词前介词用法口诀年前周前要用in 具体日子要用on 遇到几号也用on 上午下午得是in 要说某日上下午用on换in记清楚午夜黄昏用at 黎明用它也不错at用在时分前说“差”可要用上to 说"过''要用past 3.表示运动方向的介词： across, through 通过，穿过across表示横过,即从物体表面通过，与on有关，为二
昆明大观楼长联的语言文化内涵探析 大观楼位于风景秀丽的昆明西南郊滇池畔，建于康熙二十九年。大观楼四周视野开阔，滇池烟波浩渺，从西山俯瞰，大观楼掩映在湖光山色之间，可谓洋洋大观，故取名大观楼。大观楼自建成后便成了省城第一名胜，吸引了众多的文人墨客来此吟诗作画。其中乾隆年间著名寒士孙髯翁超凡脱俗，所撰写的大观楼长联堪称一绝，被后人誉为古今第一长联，大观楼也因此而扬名天下。孙髯，字髯翁，祖籍陕西三原，幼时随父入滇，天资聪颖，年轻时参加童试，因不愿受其搜身之辱，便愤然离去，从此不复参加科举考试，终生为布衣。髯翁博学多识，却贫困潦倒一生，晚年只能靠卖卜为生。他所作的大观楼长联上下联共180字，就字数而言，并不是最长者，但就思想意义和对后世的影响而论，大观楼长联古今第一的美誉实至名归。关于此联的艺术成就，前人已经做过很多的研究，但就文化内涵而言，前人涉及较少，所以本文试从语言特色和文化内涵两个方面，对长联进行剖析和解读。 一.大观楼长联的语言特色 对联是中国独特的文学艺术形式，它始于五代，盛于明清，迄今已有一千多年的历史。对联一般应该具备四个要素，一是字数相等，断句一致。但也有一些例外的情况，如民国时期有这样一幅对联，上联是袁世凯千古，下联为中国人民万岁，这副对联意在讽刺袁世凯，虽然上下联字数不等，却很符合当时中国人民的心声，所以也被接受和广泛传诵。二是平仄相合，音调和谐。对联要求上下联平仄要对应，传统习惯是仄起平收，即上联末句尾字用仄声，下联末句尾字用平声。三是要求词性相对，位置相同。一般称为虚对虚、实对实，即虚词对虚词，实词对实词。四是要求内容要相关，上下衔接。髯翁所作的大观楼长联立意高远，气势磅礴，除了具备对联的基本要素之外，在语言运用上也颇具特色，值得玩味。 （一）长联多种修辞手法的运用 长联巧妙地运用了排比、比喻、拟人等多种修辞手法，使之气势如虹，意境深远，为长联增色不少。 1.比喻修辞手法的巧妙运用 长联中巧妙地运用了比喻修辞手法，比如看东骧神骏，西翥灵仪，北走蜿蜒，南翔缟素联中就用神骏来比喻昆明东边的金马山；灵仪喻西面的碧鸡山；用蜿蜒来形容北面的长虫山；缟素喻南面的白鹤山。这样一来，就把滇池四周静态的山脉描写得活灵活现，再加上前边的看字，一幅充满生机的画面立刻展现在人们的面前，看吧：东边的金马山似神马奔驰，西边的碧鸡山像凤凰飞舞，北面的长虫山如灵蛇蜿蜒，南端的白鹤山如白鹤翱翔。此外，上联中还用蟹屿螺洲比喻滇池中沙洲的独特形状，用风鬟雾鬓比喻岸边摇曳多姿的垂柳。 2.排比修辞手法的精妙运用 长联中排比修辞手法的运用尤为突出。如东骧神骏，西翥灵仪，北走蜿蜒，南翔缟素，作者在描绘这些自然景物时，运用了空间排比的手法，将东、西、南、北四个方位词运用到句子中，构成排比句。汉习楼船，唐标铁柱，宋挥玉斧，元跨革囊，作者在概括这些历史事件时，运用了时间排比的手法，把发生在云南的历史大事按朝代顺序排列。再如上联莫辜负：四围香稻，万顷晴沙，九夏芙蓉，三春杨柳。下联只赢得：几杵疏钟，半江渔火，两行秋雁，一枕清霜。运用了景物排比和数字排比。作者并不局限于一物，而是眼观八方，笔落四面，把所看到的香稻、晴沙、芙蓉、杨柳逐一排列，并与下联的疏钟、渔火、秋雁、清霜等景物形成对仗。分别用明朗和清冷的色彩词把整个滇池周边的景物完美地呈现在读者面前。同时作者还巧妙地运用了四、万、九、三等数字排比，使长联读起来更具有节奏感。 3.典故的恰当运用 用典是指在作品中引用古人的话语或把历史故事概括说出来的一种修辞手法，用典可以使文章更加凝练。用典也是大观楼长联语言的一大特色，像汉习楼船出自《史记·平淮书》，历史史实是：汉武帝为了攻打云南滇池周边的少数民族，于是在长安大修昆明池，治
英语方位词的用法 (一)in the east 与 on the east的区别 1．in the east表示我们生活中和地理位置上的绝对方向。如： The sun rises in the east and sets in the west. 太阳从东边升起，从西边落下。 The Great Wall begins in the east from the Shanghaiguan Pass and ends at the Jiayu guan Pass in the west. 长城东起山海关，西至嘉峪关。 2．on the east表示某事物位于另一事物所朝的方向。这里的方向是相对而言的。如： China faces the Pacific on the east. 中国东临太平洋。 The United States faces the Atlantic on the east and the Pacific on the west. 美国东临大西洋，西濒太平洋。 (二) in (to，on，at) the east of 1．要表示A在B的东部，即：A在B的范围之内时就用"A is in the east of B"，如： Japan is in the east of Asia.日本在亚洲东部。 Italy is in the south of Europe.意大利在欧洲南部。 2．如果A在B的东方，即：A在B的范围之外，且相隔有一定的距离，就用"A lies to the east of B".口语中有时可将to the省去。如： Japan lies (to the) east of China.日本位于中国东方。 France lies (to the) east of England.法国位于英国东方。 3．如果A在B的东边(侧)，即：A与B相邻接。就用"A is on the east of B". 如： Guangdong is on the south of Hunan.广东在湖南南边。
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.