20.1 段落展开的方式与文体类型
20.1A 段落展开的方式
1） 前面19.2A讲到，段落要有明确的中心。我们开始写一个段落时，脑子里想到的就是如何表达好这个段落中心。下面是假设的一个段落：
I enjoy listening to music. Music makes me feel relaxed and brightens my mood. So I listen to it every day.
这个段落展开得不够。老师看到学生这样的段落时可能会批上“dev（elopment）”，or “det（ail）” 这样的标记，还可能进一步写上这样的批语：“This idea needs more development.” 或“Don't just generalize, give some examples.”
2） 段落展开的方式很多，亦富于变化，但归结起来，有几种方式是基本的，常见的。
让我们再回到上面的那个例子。其中第三句显得有点重复，可以删去，然后根据所要表达的中心思想加以展开：
一种是增加具体例子（For example ...），如爱听哪些音乐，或者某日听了某个乐曲后得到的感受和效果。这样的段落就叫做“说明”（Exposition）。
另一种是笔锋一转：“... But some people don't think so. They say that listening to music makes one either too excited or rather depressed ...” 接着以自己的观点说服对方，同时介绍一下在不同情况下选听不同音乐的经验。这样的段落就属于“辩论”（Argumentation）或“劝说”（Persuasion）。
第三种是接下去叙述自己听音乐的经历，如：“... In fact, I began to be interested in music at the age of four when one day my parents took me to a concert ...”，然后逐步说明怎样随着年岁的增加越来越爱好音乐。这样一写，就成了我们所说的“记叙”（Narration）。
第四种是接下去写：“... Here is a piece of ...”详细描写某个乐曲的音韵、意境，等等，那就会成为一种“描写”（Description）段落了。
20.1B 四种基本文体类型
1） 前面讲到段落展开的4种基本方式，于是有“说明”、“辩论”、“记叙”和“描写”4种段落，这也就是文体的4种基本类型。
2） 文体（Types of writing）不同于文章风格（Styles of writing）。文体指文章的基本结构和写作特点，不同的文体表示不同的写作目的，故而有说明、描写、记叙和辩论等。文章风格指写作的风格、特色。各个作家都有自己的风格特点，每个人所写的东西也会有自己的风格特色，如有的华丽，有的庄重，有的通俗，有的隐晦，有的明快，有的呆板，有的生动，等等。文章风格也会有共性，因而有诸如维多利亚文风（the Victorian Style）、浪漫派的文风（Style of the Romantic School）等不同的名称。
不同的文章风格可以体现在各种文体之中，例如不同作家在描写同一个景物时就会出现不同的风格。
3） 虽然在一篇较长的文章中可能既有说明段落，又有记叙段落，以及描写、辩论段落等，但总有一种是主体性的。例如一篇说明文的基本特点是说明体，可以看作是说明段落的扩展，为此，我们把这4种段落的特点也作为4种文体的特点。
20.2 说明
20.2A 说明段落的结构特点
1） 说明可能是最基本、最常用的文体，用于说明事实、情况和传递信息等。人们进行说明时，通常都是通过例子使自己的说明具体化，因而可以概括出这样一个格式：
Generalization+Illustration（s）
下面是Eric Hoffer所写的一段说明文：
The undercurrent of admiration in hatred manifests itself in the inclination to imitate those we hate. Thus every mass movement shapes itself after its specific devil. Christianity at its height realized the image of the antichrist. The Jacobins practiced all the evils of the tyranny they had risen against ... Russia is realizing the purest and most colossal example of monopolistic capitalism. Hitler took the Protocols of the Wise Men of Zion for his guide and textbook; he followed them “down to the veriest detail.”
（The True Believer）
段中的前两句为Generalization部分，后面为Illustrations部分。在Generalization的两句中，还可以进一步划分Subject或Topic Sentence（主题句）加Restriction，即对主题句加以必要的说明、限定，也有时不加Restriction而只用主题（句）。在Illustration部分可以用几个例子，也可以只用一个例子，视具体情况而定。有的段落还可能再加上一个结尾（Conclusion），同开头的主题（句）相呼应。
2） 上面讲到的“Subject+Restriction+Illustration（s）”的格式，其中的次序也可倒过来，前者称为“演绎法”（Deductive Method），后者叫做“归纳法”（Inductive Method）。下面是一个“归纳法”的段落：
Under a canopy of hickory and oak trees file people of all ages and sizes, some neatly dressed in street clothes formal enough for lunch at the Tavern, others in sloppy jeans and fringed jackets, with huge, floppy, handcrafted leather hats on their heads, and here and there, some older women in the long gingham dresses and sunbonnets characteristic of the Appalachian farm wife. They file past booths topped with red, yellow, and blue-striped canvas and filled with the handicrafts traditional to this fair: thin, beautifully polished wooden trays, brightly colored enamelware, rainbows of cornstalk flowers, and macramé wall hangings sharing the limbs of trees with sandcastle candles. Near the gate the loud clatter of a corn-meal grinder can be heard, interspersed in the quiet pauses between customers with the plucking of dulcimer strings and the soft crooning of mountain singers. This Mardi Gras scene, greeting the newcomer to the Berea Arts and Crafts Fair, is an annual rite of spring. This gentle orgy, one of several in the area, is a reaffirmation that traditional craftsmanship is alive and well and still flourishes in Appalachia.
（Michael E. Adelstein & Jean G. Pival）
2） 除了举例说明外，还可以使用过程说明、比较对比说明、因果关系说明、分类说明、定义说明等。让我们在以下各节中分别加以讨论。
20.2B 过程分析
过程分析（Process analysis）是按事物进展的先后次序进行说明，包括时间顺序、位置指引、操作程序等。
1）按时间顺序（Temporal Order / Chronological Sequence） 说明。例如：
This time it happened to Sonny, and in the very first minutes of play. Leroy Malone managed to trip the gangly Paducah center and while the center was sprawled on the floor Sonny ran right along his back, in pursuit of the ball. Just as he was about to grab it somebody tripped him and he hit the wall head first. The next thing he knew he was stretched out beside the bench and one of the freshmen players was squeezing a wet washrag on his fore-head. Sonny tried to keep his eyes closed as long as he could — he new Coach Popper would send him back into the game as soon as he regained consciousness. He feigned deep coma for about five minutes, but unfortunately the coach was experienced in such matters. He came over and lifted one of Sonny's eyelids and saw that he was awake.
（Larry McMurtry）
关于因果关系说明，参见19.2B4。
2） 位置指引（Locational instructions），常见于对问路人的回答或告诉某人具体地点。以下面一段对话为例：
Locksmith: I'm Jack Jones from National Lock and Key Company. I'm supposed to change a lock on Ms. Grady's desk.
Receptionist: Yes, I've been expecting you. Ms. Grady's office is on the third floor, Office 301. You'll notice identifying numbers over the door. After you enter the office, go to the desk on the left. As you face the desk, the drawer on the right is the one that needs to have the lock replaced.
3） 操作程序说明（Operational instructions）中常用祈使句，其中第二人称作为主语往往省略。例如：
First, （you） unplug the appliance. Use the fingers to turn it counterclockwise until it can be removed. Then with a Phillips screwdriver carefully remove the back plate.
（N. A. Pickett & A. A. Laster）
对于比较复杂的操作程序，有时可分为“Step 1, Step 2, ...”逐步说明，最后还可视情况需要附上Precautions或Warnings等内容，以保证操作顺利进行。
20.2C 比较和对照
1） 比较和对照（Comparison and Contrast）是就两个对象之间的相同点和不同点 （Similarities and Differences） 进行说明。这里是评论家 Matthew Arnold针对Robert Burns和Geoffrey Chaucer两位诗人所写的一个段落，结尾为该段落的主题句：
Yet we may say of [Burns] as of Chaucer, that of life and the world, as they come before him, his view is large, free, shrewd, benignant-truly poetic, therefore; and his manner of rendering what he sees is to match. But we must note, at the same time, his great difference from Chaucer. The freedom of Chaucer is heightened, in Burns, by a fiery, reckless energy; the benignity of Chaucer deepens, in Burns, into an overwhelming sense of the pathos of things; — of the pathos of human nature, the pathos, also, of non-human nature. Instead of the fluidity of Chaucer's manner, the manner of Burns has spring, bounding swiftness. Burns is by far the greater force, though he has perhaps less charm.
2） 有时专门就两个对象之间的不同点加以对照，例如下面一个段落：其中第一句为该段的主题句，然后是从几个方面说明父亲和母亲之间的不同之处，最后两句为全段小结，同句首相呼应。
Opposites seem to attract. My father is tall, blond, and outgoing. My mother is small, and even her dark brown hair, which is naturally wavy, has a certain quiet repose about it. My dad does everything at a cheerful run, whether he is off to a sales conference or off to the golf course with his foursome on Saturday mornings. My mother never seems to hurry. She hums at her work, and the house seems to slip into order without effort. She plays bridge with a few friends, and belongs to a number of organizations, but she is just as happy with a book. When dad bursts in at the end of the day, her face lights up. They grin at each other. They obviously still find each other attractive.
（Sheridan Baker）
3） 在对两个对象的相同/相似点加以比较时，往往采用“类比”（Analogy）的形式 （参见9.1），或者说是一个扩展的“隐喻” （Metaphor, 参见8.2）。下面是E. B. White对Thoreau的Walden的一段分析：开头一句（主题句）就是一个类比，然后分两个层次加以扩展（... he rides into the subject at top speed ... and when the shooting dies down ...）。
Thoreau's assault on the Concord society of the mid-nineteenth century has the quality of a modern Western: he rides into the subject at top speed, shooting in all directions. Many of his shots ricochet and nick him on the rebound, and throughout the melee there is a horrendous cloud of inconsistencies and contradictions, and when the shooting dies down and the air clears, one is impressed chiefly by the courage of the rider and by how splendid it was that somebody should have ridden in there and raised all that ruckus.
（E. B. White: A Slight Sound at Evening）
20.2D 分类和定义
1） 客观事物常常可以按照人们的习惯加以分类（Classifications）, 如大学生分成freshman, sophomore, junior, senior; 法律界分为legislative, executive, judicial; 交通分land, air and water communications，等等，而且还可以进一步划分为subclasses。下面是一段以分类法说明巴拿马运河涉及的问题的文章：
Building the Panama Canal posed problems of politics, geology, and human survival from the beginning. A French company, organized in 1880 to dig the canal, repeatedly had to extend its treaties at higher and higher prices as the work dragged on. Uneasy about the French, the United States made treaties with Nicaragua and Costa Rica to dig along the other most feasible route. This political threat, together with the failure of the French and the revolt of Panama from Colombia, finally enabled the United States to buy the French rights and negotiate new treaties, which, nevertheless, continue to cause political trouble to this day. Geology also posed its ancient problems: how to manage torrential rivers and inland lakes; whether to build a longer but more enduring canal at sea level, or a shorter, cheaper, and safer canal with locks. Economy eventually won, but the problem of yellow fever and malaria, which had plagued the French, remained. By detecting and combating the fever-carrying mosquito, William Gorgas solved these ancient topical problems. Without him, the political and geological solutions would have come to nothing.
（Sheridan Baker）
2） 为了说明问题，常常需要对一些词语——尤其是那些抽象的、技术性的关键词语下定义。定义的方式主要有：
同义释义（Defining by Synonym），如：
Apathetic means “indifferent”. （Not “indifference”。）
Prevaricate means “lie.” （Not “lying”.）
举例释义（Defining by Example），如：
A planet is a heavenly sphere such as Jupiter, Mercury, Mars, or Earth.
词根释义（Defining by Etymology），如：
Intuition comes from the Latin words “in” （meaning “in” or “into”）and “tueri”, （meaning “look” or “gaze”）. Literally, therefore, it means a “looking inward”.
比较、对照或类比释义（Defining by Comparison, Contrast, or Analogy），如：
While burglary is the stealing of property from a place, robbery is the stealing of property from a person.
功能释义 （Defining by Function）, 如：
An orthopedist treats bone diseases.
An ombudsman defends an individual in a conflict with the government or an institution.
反义释义 （Defining by Negation）, 如：
A widow refers to a woman whose husband is not living and who has not married.
“反义释义”法可以扩展为段落，其方法可以归纳为四步推理法： a. what it is not like; b. what it is like; c. what it is not; d. what it is.例如：
Love may be many things to many people, but, all in all, we agree on its essentials. Love is not like a rummage sale, in which everyone tries to grab what he wants. It is more like a Christmas, in which gifts and thoughtfulness come just a little unexpectedly, even from routine directions. Love, in short, is not a matter of seeking self-satisfaction; it is first a matter of giving and then discovering, as an unexpected gift, the deepest satisfaction one can know.
上述4个步骤还可以扩展为4个段落。这4个步骤也可以反过来，以逆序形式构成释义段落。例如：
Black Power means, for example, that in Lowndes County, Alabama, a black sheriff can end police brutality. A black tax assessor and tax collector and county board of revenue can lay, collect, and channel tax monies for the building of better roads and schools serving black people. In such areas as Lowndes, where black people have a majority, they will attempt to use power to exercise control. This is what they seek: control. When black people lack a majority, Black Power means proper representation and sharing of control. It means the creation of power bases, of strength, from which black people can press to change local or nation-wide patterns of oppression — instead of from weakness.
It does not mean merely putting black faces into office. Black visibility is not Black Power. Most of the black politicians around the country today are not examples of Black Power. The power must be that of a community, and emanate from there. The black politicians must start from there. The black politicians must stop being representatives of “downtown”machines, whatever the cost might be in terms of patronage and holiday handouts.
（Stokely Carmichael and Charles V. Hamilton: Black Power, the Politics of Liberation in America）
练习二十 （Exercise Twenty）
I. Preview Questions:
1. What do you think of the statement that each paragraph must have a clear center of thought?
2. What does one mean when he says that a certain paragraph needs further development?
3. What are the basic types of writing?
4. Which of the four basic types of writing is used most frequently in your life?
5. Do you think that Exposition usually follows the pattern of “Generalization plus Illustration”?
6. Do you always use a topic sentence when you write an expository paragraph?
7. What are the three basic approaches people may use in “Process Analysis”?
8. What do you usually try to indicate when you resort to “Comparison and Contrast”?
9. How many ways can you make definitions?
10. Have you ever used the principle of “Defining by Negation” in a paragraph development?
II. Read the following paragraphs and analyse them as indicated:
1. Point out the topic sentence and the steps concerning having fresh shrimp in the following paragraph：
When fresh shrimp can be had, have it. What size? Medium for reasons of economy and common sense. Huge shrimps are magnificently expensive while small ones come in such numbers per pound that shelling them becomes slave labor. Buy two pounds of fresh shrimp and shell them. First, with a thumbnail pinch the tail shell hard crosswise （so the tail segments will come out intact）, then handle the headless animals like so many pea pods; split them lengthwise, save the contents, and throw the husks away. Sauté the shrimp with three crushed garlic cloves in two-thirds of a stick of butter. When the shrimp turn pink, add a 12-ounce can of Italian tomatoes （which taste better than the fresh supermarket kind）,two bay leaves, a teaspoon of dried oregano, a half-cup of dry white wine, and the juice of a lemon. Simmer for ten minutes, sprinkle with chopped parsley and serve with rice.
（Philip Kopper）
2. Identify the sentences that state the cause and effect in this paragraph:
On December 1, 1955, an attractive Negro seamstress, Mrs. Rosa Parks, boarded the Cleveland Avenue Bus in downtown Montgomery. She was returning home after her regular day's work in the Montgomery Fair — a leading department store. Tired from long hours on her feet,Mrs. Parks sat down in the first seat behind the section reserved for whites. Not long after she took her seat, the bus operator ordered her, along with three other Negro passengers, to move back in order to accommodate boarding white passengers. By this time every seat in the bus was taken. This meant that if Mrs. Parks followed the driver's command she would have to stand while a white male passenger, who had just boarded the bus, would sit. The other three Negro passengers immediately complied with the driver's request. But Mrs. Parks quietly refused. The result was her arrest.
