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exercise 17-2
directions：write a paragraph，analyzing the advantages of job interview.
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第十八单元 推展段落方法之九——因果法（2）
18.1原因法
有时，一个结果会源于几个原因。同样，段落可或以结果开头或以结果结束，作者可以从熟悉到不熟悉的原因逐一分析，或是从分析一个又一个读者不熟悉的原因开头，最后引出读者熟悉的结果。选用哪一种，决定于作者认为哪一种更有说服力。
示范段落18-1
several changes have brought wild animals to the cities.foremost is，that air and water quality in many
cities have improved as a result of the 1970's pollution control efforts.meanwhile，rural areas have been built up，leaving many animals on the edges
of suburbs.in addition，urban wildlife refuges have been
created.the greater
london council last year spent ＄750,000 to buy land and build 10 permanent wildlife refuges in the
city.as a result，many big birds are now living in
the city.for peregrine
falcons cities are actully safer than rural cliff dwellings.by 1970 the birds had died out east
of the mississippi because ddt had made their eggs too thin to support life.that year，scientist tom cade of cornell
university began raising the birds for release in cities，for cities afforded plentyof food.
18.2 示范段落分析
主题句：several changes have brought
wild animals to the cities.
因果模式（cause-effect pattern）：
结果（effect）：wild animals back to the cities
原因（causes）： 1.air and water quality have improved.
2.rural areas
have been built up.
3.urban
wildlife refuges have been created.
18.3 因—果—因法
有时候，一个原因也许会引起一个结果，这个结果又成为另一个结果的原因，如示范段落18-2所示。
示范段落18-2
for some time now，medical scientists have noted an alarming increase in disease of the
heart and circulation among people who smoke cigarettes.it has been found that the presence
of nicotine in the blood stream causes blood vessels to contract，thus slowing circulation，which eventully leads to hardening
of the arteries.as the
arteries stiffen，less blood
reaches the brain，and the end
result of this slowdown is the cerebral hemorrhage，commonly referred to as a“stroke”.in addition，nicotine in the bloodstream reduces
the ability of the hemoglobin to release oxygen，resulting in shortness of breath.the lack of oxygen forces the heart to beat faster—that is，the pulse rate increases—and in turn accelerates the risk of
heart attack.
18.4.示范段落分析
因-果-因模式（cause-effect-cause
pattern）：
smoking tobacco→nicotine in the blood streams
→the blood vessels constract…
18.5 关于写因果段落的建议（续）
3）着重分析直接的、明显的原因
每个结果都有无数的原因，同样，每个行为都会导致无数的结果。因果段落应只着重分析直接的、明显的原因，忽略间接的原因。例如，一个学生成绩不好，直接原因是没有认真学习，间接原因也许是对学校不满。显然，我们应该着眼于直接的原因而摒弃间接的原因。
4）根据重要性或熟悉程度排列细节（见第19单元）
5）使用适当的排列符号（listing
signals）（见第34单元）
exercise 18-1
directions：read the following paragraph of cause and effect，adding suitable listing signals and
linking expressions.
there are many reasons why languages change.____，
various languages that started from the same parent developed their
own uniqueness after groups of speakers drifted away from one another to
establish isolated，independent communities.________is the independence of and interaction with foreign cultures，often as a result of military
conquest.________is
rapidly expanding technologe and new systems of communication that bring all
cultures and languages into close contact，with borrowing between languages a common phenomenon in the
contemporary world.all languages change as the experiences of their speakers change.
exercise 18-2
directions：write a paragraph analyzing the causes of students cheating on exams.
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第十九单元 组织段落方法——重要性和熟悉度顺序
19.1 重要性顺序排列法
前面我们已经讨论了组织段落的两种方法——时间顺序法（time-order）和空间顺序法（space-order）。组织段落的第三种方法是根据重要性排列的方法（to organize
details according to their order of importance）。作者使用这种方法的依据是他认为所选用的细节应如何加以强调。
使用重要性顺序法，可选用上升顺序（ascending order），或下降顺序（aescending oraer）。前者先列举次要观点，把重要的留到最末（如示范段落17-1），后者先强调最重要的观点，然后列举次要观点（如示范段落4-1）。
19.2 熟悉度顺序排列法
对于某些段落，也许使用熟悉度顺序法（order of
familiarity）更恰当。这种方法根据读者对作者所选用的一系列细节的熟悉程度排列。例如，在分类段落中，作者经常先谈论读者比较熟悉的、具体的细节，然后谈论读者不大熟悉的细节，如示范段落16-1。
19.3 使用顺序法的一般准则
到目前为止，我们共讨论了四种组织段落顺序，使用哪一种顺序取决于作者的写作目的和读者对主题的熟悉程度。
1）如果你要说服别人相信一个观点，应该选用重要性顺序，把最好和最有力的理由放在能使读者最容易牢记的地方——段末。
2）如果你要向读者准确地展示一个场面，则应选用空间顺序描述，以便你的读者能够在脑海中再现你所描绘的画面。
3）如果读者对你要谈论的话题不大熟悉，则应从熟悉的观点着手。
4）如果你要告诉读者发生了什么事情或怎样做某件事，则需要时间顺序。
exercise 19-1
directions：read the following two paragraphs and analyze their orders of
organization.