首先，一个段落必须有一个中心即主题思想，该中心由主题句特别是其中的题旨来表达。整个段落必须紧扣这个主题(tick or hold to the topic)，这就是段落的统一性(unity)。
其次，一个段落必须有若干推展句，使主题思想得到充分展开，从而给读者一个完整的感觉，这就是完整性(completene or adequatene)。
再者，一个段落不是杂乱无章的，而是有机的组合，句子的排列顺序必须合乎逻辑，从一个句子到另一个句子的过渡必须流畅(mooth)，这就是连贯性(coherence)。
下面我们就对这三个标准分别加以说明。
1. 统一性
一个段落内的各个句子必须从属于一个中心，任何游离于中心思想之外的句子都是不可取的。
请看下例：
Joe and I decided to take the long trip we'd alway wanted acro the country. We were like young kid buying our camper and tocking it with all the neceitie of life. Bella bake the bet rhubarb pie. We tarted out in early pring from Minneapoli and headed wet acro the northern part of the country. We both enjoyed thoe people we met at the trailer park. Joe received a watch at hi retirement dinner. To our urprie, we found that we liked the warm outhern region very much, and o we decided to tay here in New Mexico.WWw.hAOZUowEn.com
本段的主题句是段首句，controlling idea（中心思想）是take the long trip acro the country。文中出现两个irrelevant entence，一个是Bella bake the bet rhubarb pie，这一段是讲的是Joe and I ，中间出现一个Bella是不合适的。还有，Joe received a watch at hi retirement dinner这一句更是与主题句不相关。考生在四级统考的作文卷上常常因为造出irrelevant entence（不相关语句）而丢分，值得引起注意。
再看一个例子：
My name i Roeanna, and I like to keep phyically fit. I ued to weigh two hundred pound, but I joined the YMCA for an exercie cla and diet program. In one year I lot eighty pound. I feel much better and never want to have that much weight on my five-feet frame again. I bought two new uitcae lat week. Everyday I practice jogging three mile, wimming fifteen lap, lifting twenty-pound weight and playing tenni for one hour. My mother wa a premature baby.
本段的controlling idea 是like to deep phyically fit，但段中有两个irrelevant entence，一个是I bought two new uitcae lat week，另一个是My mother wa a premature baby。
从上面两个例子可以看出，native peaker同样会造出来irrelevant entence。卷面上如果这种句子多了，造成偏题或离题，那问题就更严重了。
2． 完整性
正象我们前面说得那样，一个段落的主题思想靠推展句来实现，如果只有主题句而没有推展句来进一步交待和充实，就不能构成一个完整的段落。同样，虽然有推展句，但主题思想没有得到相对圆满的交待，给读者一种意犹未尽的感觉。这样的段落也不能完成其交际功能。例如：
Phyical work can be a ueful form of therapy for a mind in turmoil. Work concentrate your thought on a concrete tak. Beide, it i more ueful to work ---- you produce omething rather than more anxiety or depreion.
本段的主题句是段首句。本段的两个推展句均不能回答主题句中提出的问题。什么是 ＂a mind in turmoil＂（心境不平静）Phyical work又如何能改变这种情况？为什么它能起therapy的作用？读者得不到明确的答案。
由于四级统考的作文部分只要求写一篇100～120个词的三段式短文，每一段只有大约40个词左右，因此，要达到完整就必须尽可能地简明。
例如：
It i not alway true that a good picture i worth a thouand word. Often writing i much clearer than a picture. It i ometime difficult to figure out what a picture mean, but a careful writer can almot alway explain it.
段首句所表达的主题思想是一种看法，必须有具体事例加以验证。上述两个推展句只是在文字上对主题作些解释，整个段落内容空洞，简而不明。如果用一两个具体的例子的话，就可以把主题解释清楚了。
比如下段：
It i not alway true that a picture i worth a thouand word. Sometime, picture are pretty uele thing. If you can't wim and fall in the river and tart gulping water, will you be better off to hold up a picture of yourelf drowning, or tart creaming "Help"?
3．连贯性(coherence)
连贯性包括意连和形连两个方面，前者指的是内在的逻辑性，后者指的是使用转换词语。当然这两者常常是不可分割的。只有形连而没有意连，句子之间就没有内在的有机的联系；反之，只有意连而没有形连，有时行文就不够流畅。
1） 意连
段落中句子的排列应遵循一定的次序，不能想到什么就写什么。如果在下笔之前没有构思，边写边想，写写停停，那就写不出一气呵成的好文章来。下面介绍几种常见的排列方式。
A．按时间先后排列(chronological arrangement)
例如：
We had a number of cloe call that day. When we roe, it wa obviouly late and we had to hurry o a not to mi breakfat; we knew the dining room taff wa trict about cloing at nine o'clock. Then, when we had been driving in the deert for nearly two hour ----- it mut have been cloe to noon ---- the heat nearly hid u in; the radiator boiled over and we had to ue mot of our drinking water to cool it down. By the time we reached the mountain, it wa four o'clock and we were exhauted. Here, judgement ran out of u and we tarted the tough climb to the ummit, not realizing that darkne came uddenly in the deert. Sure enough, by ix we were truggling and Andrew very nearly went down a teep cliff, dragging Mohammed and me along with him. By nine, when the wind howled acro the flat ledge of the ummit, we knew a we hivered together for warmth that it had not been our lucky day.
本段从 ＂roe＂（起床）写起，然后是吃早餐(＂not to mi breakfat＂, ＂cloing at nine o'clock＂)，然后是 ＂cloe to noon＂，一直写到这一天结束(＂By nine--")。
B. 按位置远近排列(patial arrangement)。
例如：
From a ditance, it looked like a kinny tube, but a we got cloer, we could ee it fleh out before our eye. It wa tubular, all right, but fatter than we could ee from far away. Furthermore, we were alo atonihed to notice that the building wa really in two part: a pagoda itting on top of a tubular one-tory tructure. Standing ten feet away, we could marvel at how much of the pagoda wa made up of gla window. Almot everything under the wonderful Chinee roof wa made of gla, unlike the tube that it wa itting on, which only had four. Inide, the tube wa gloomy, becaue of the lack of light. Then a teep, narrow taircae took u up inide the pagoda and the light changed dramatically. All thoe window let in a flood of unhine and we could ee out for mile acro the flat land.
本段的写法是由远及近，从远处(＂from a ditance＂)写起，然后＂get cloer＂，再到(＂ten feet away＂)，最后是 ＂inide the pagoda＂……当然，按位置远近来写不等于都是由远及近。根据需要，也可以由近及远，由表及里等等。
C. 按逻辑关系排列(logical arrangement)
a. 按重要性顺序排列(arrangement in order of importance)
If you work a a oda jerker, you will, of coure, not need much kill in expreing yourelf to be effective. If you work on a machine, your ability to expre yourelf will be of little importance. But a oon a you move one tep up from the bottom, your effectivene depend on your ability to reach other through the poken or the written word. And the further away your job i from manual work, the larger the organization of which you are an employee, the more important it will be that you know how to convey your thought in writing or peaking. In the very large buine organization, whether it i the government, the large corporation, or the Army, thi ability to expre oneelf i perhap the mot important of all the kill a man can poe.
这一段谈的是表达能力，它的重要性与职业，身份有关，从＂not need much kill"或 "of little importance"到 "more important"，最后是 "mot important"。
b.由一般到特殊排列（general-to-pecific arrangement）
If a reader i lot, it i generally becaue the writer ha not been careful enough to keep him on the path. Thi carelene can take any number of form. Perhap a entence i o exceively cluttered that the reader, hacking hi way through the verbiage, imply doen't know what it mean. Perhap a entence ha been o hoddily contructed that the reader could read it in any of everal way. Perhap the writer ha witched tene, or ha witched pronoun in mid-entence, o the reader loe track of when the action took place or who i talking. Perhap entence B i not logical equel to entence A ---- the writer, in whoe head the connection i clear, ha not bothered to provide the miing link. Perhap the writer ha ued an important word incorrectly by not taking the trouble to look it up. He may think that "anguine" and "anguinary" mean the ame thing, but the difference i a bloody big one. The reader can only infer what the writer i trying to imply.
这一段谈的是a writer' carelene，先给出一个general tatement作为主题句，然后通过5个 ＂perhap＂加以例证。
c. 由特殊到一般排列(pecific-to-general arrangement)
I do not undertand why people confue my Siamee cat, Priy, with the one I had everal year ago, Henry. The two cat are only alike in breed. Priy, a quiet, feminine feline, love me dearly but not poeively. She like to keep her ditance from people, exert her independence and i never o rude a to beg, lick, or niff unceremoniouly. Her uual poture i itting upright, eye cloed, perfectly till. Priy i a very proper cat. Henry, on the other hand, loved me dearly but poeively. He wa my hadow from morning till night. He expected me to contantly entertain him. Henry never cared who aw him do anything, whether it wa decorou or not, and he uually offended my friend in ome way. The cat made himelf quite comfortable, on the top of the televiion, acro tranger' feet or lap, in bed, drawer, ack, cloet, or nook. The difference between them i imperceptible to tranger.
本段的主题句是段首句，它仅提出一个问题：为什么两只猫会被搞混。然后对两者进行比较，末句才下结论。
2） 形连
行文的逻辑性常常要靠适当的转换词语及其他手段来实现。请读下面这一段文字并找出文中用以承上启下的词语：
Walter' goal in life wa to become a ucceful urgeon. Firt, though, he had to get through high chool, o he concentrated all hi effort on hi tudie --- in particular, biology, chemitry, and math. Becaue he worked contantly on thee ubject, Walter became proficient in them; however, Walter forgot that he needed to mater other ubject beide thoe he had choen. A a reult, during hi junior year of high chool, Walter failed both Englih and Latin. Conequently, he had to repeat thee ubject and he wa almot unable to graduate on chedule. Finally, on June 6, Walter achieved the firt tep toward realizing hi goal.
本文中起承上启下的词语有两种，一种是转换词语(tranitional word or phrae)，另一种是起转换作用的其他连接手段(linking device)。前者依次有：firt, though, o, in particular, and, becaue, however, beide, a a reult, both…and, conequently, and, finally.后者依次是：he, he, hi, hi, he, thee, them, he, thoe, hi, he, thee, hi. 本段中共有词汇105个，所使用的转换词语及其他连接用语共26个词，约占该段总词汇量的四分之一。由此可见，掌握好tranition不仅对行文的流畅(moothne)有益，而且对于学生在半个小时内写足四级短文所要求的120个词也是不无好处的。
一个段落里如果没有tranition也就很难有coherence了.
我们看下面一个例子：
Speaking and writing are different in many way. Speech depend on ound. Writing ue written ymbol. Speech developed about 500 000 year ago. Written language i a recent development. It wa invented only about ix thouand year ago. Speech i uually informal. The word choice of writing i often relatively formal. Pronunciation and accent often tell where the peaker i from. Pronunciation and accent are ignored in writing. A tandard diction and pelling ytem prevail in the written language of mot countrie. Speech relie on geture, loudne, and rie and fall of the voice. Writing lack geture, loudne and the rie and fall of the voice. Careful peaker and writer are aware of the difference.
本段中除了第6句开头出现一个起过渡作用的＂it＂之外，没有使用其他的过渡词语.这样，文中出现许多重复的词语，全段读起来也显得生硬而不自然。如果加上必要的过渡词语来修饰的话，这一段就成了下面一个流畅连贯的段落：
Speaking and writing are different in many way. Speech depend on ound; writing, on the other hand, ue written ymbol. Speech wa developed about 500 000 year ago, but written language i a recent development, invented only about ix thouand year ago. Speech i uually informal, while the word choice of writing, by contrat, i often relatively formal. Although pronunciation and accent often tell where the peaker i from, they are ignored in wiring becaue a tandard diction and pelling ytem prevail in mot countrie. Speech relie on geture, loudne, and the rie and fall of the voice, but writing lack thee feature. Careful peaker and writer are aware of the difference．
4． 有损连贯性的几种情况：
考生在写作中经常出现下面几种错误：
1）不必要的改变时态，
比如：
In the movie, Robert Redford wa a py. He goe to hi office where he found everybody dead. Other pie wanted to kill him, o he take refuge with Julie Chritie. At her houe, he had waited for the heat to die down, but they come after him anyway.
2）不必要的改变单复数，
比如：
Everybody look for atifaction in hi life. They want to be happy. But if he eek only pleaure in the hort run, the peron will oon run out of pleaure and life will catch up to him. They need to purue the deeper pleaure of atifaction in work and in relationhip.
3）不必要的改变人称，
比如：
Now more than ever, parent need to be in touch with their children' activitie becaue modern life ha the tendency to caue cleavage in the family. You need to arrange family like
it o that family member will do thing together and know one another. You need to give up iolated pleaure of your own and realize that parent have a et of obligation to ponor togetherne and therefore ponor knowledge.
因此写作中，一定要注意时态，人称以及数的变化是否正确，要注意保持一致。