商业书信必须写得正确，因为它涉及到买卖双方的权利、义务和厉害关系，是各种商业单据的依据。广义的说，商业书信的正确性表现在：
（一）运用正确的语言水平
（二）叙述得正确
（三）数字要正确
（四）正确理解和运用商业术语
（五）合适的写作技巧或方法，以及正确运用其他的六个"C"。
（一）正确的语言水平
(1)、正式的和非正式的语言水平所用词汇比较：
formal informal
terminate
domicile
deem
transpire
conflagration
edifice
endeavor
obtain; procure
peruse
remunerate
utilize
subsequent
ascertain
contingent upon
anticipate
interrogate end
home
think(or: believe)
happen
fire
building
try
get
read or study
pay
use
next or following
find out
depending on
expect
ask
(2)、正式的和非正式的语言比较
formal informal
Will attain the age of 18 years. Will be 18 years old
Render us more detail
We will institute a mail search Send us more information
We will ask the post office to send out a tracer.
We thank you in anticipation of this courtesy and assure you that it will be a pleasure to serve you in a similar manner We shall appreciate your helping us. Let us know when we can return the favor.
Inform me of your intentions as to the liquidation of this balance Let me know when you can settle this account.
Give consideration to a plan. Consider a plan
This plan will effect a saving of $10,000. This plan will save $10,000.
To effect certain modifications in a procedure contingent upon the concurrence of management To make certain changes if management agrees.
The conclusions ascertaind from a perusal of the pertinent data is that a lucrative market exists for the product in this vicinity.
The data studied show that the product is in good demand in this area.
(3)、避免使用不标准的语言
不要说 应该说
ain''t
hadn''t ought
irregardless
nohow
in regard to
can''t hardly
between you and I
where ….at isn''t, aren''t
shoudn''t
regardless
anyway
regarding
can hardly
between you and me
where
下面的内容是用三种不同语言水平的比较参考：
Formal: Although Item 12 is enumerated in the report, the writer has ascertained that it is currently not in the organization''s inventory or in the writer''s possession.
Informal: Although Item 12 is listed in the report, it''s not in our stock now and I don''t have it either.
Standard: Irregardless of the report that item ain''t on our shelves now, and I haven''t got it either.
（二）叙述得正确
商业书信的内容要叙述得正确，既不能说得不够(Understatement)，更不能说得过头(Overstatement)。
例一： This stove is absolutely the best (or: the very best) on the market.
（这种炉子是市场上绝对最好的炉子。）
这句话是用来介绍商品的，但没有具体介绍商品的性能，而是抽象地断定这种炉子是“市场上最好的”。这样介绍商品，不但不能达到推销的目的，反而使人对写信人有“卖狗皮膏药”的感觉。
改写：
Our model A195 is designed on modern lines and gives, without any increase in fuel consumption, 25% more heat than the older models. So you will agree that it is the outstanding stove for economy of fuel.
(我们的A195型炉子是按近代样式设计的，在不增加燃料消耗的情况下，比其他各种旧式炉子温度高25%。所以，你会同意，这是个优良的节约燃料的炉子。)
（三）字要正确
做对外贸易离不开数字。对商业书信中的数字的正确性要特别加以注意，有时“失之毫厘，差之千里”。甚至引起不同的理解。
（a）“以上”，“以下”，“以前”，“以后”，“从……到……”等的表达法。
$2 or (and) above(over) 二美元和二美元以上
60dozen or (and) up (upward, upwards) 60打和60打以上
2% or (and) more 2%和2%以上
an order for 50 gross or upward 50罗或50罗以上的定单
an order for not less than 50 gross 不少于50罗的定单
5% up to 10% inclusive 5%到10%
over 5% up to 10% inclusive 5%以上到10%
（b）
from and including today(this date) 从今日起（包括今日）
on and from Nov. 10; 从11月10日起
on and after Nov.10; （包括11月10日）
as from Nov.10 从毁约之日起
as from the date of the breach （包括毁约之日）
up to $40 inclusive; 到40美元
up to the maximum of $40 （包括40美元）止
up to and including Nov.20 到11月20日止
（包括11月20日）
as from the 1st to the 15th of March inclusive; 从3月1日到15日
from the 1st to 15th of March both inclusive （包括1日和15日）
during the period beginning on 从3月1日起到3月30日止
March 1 and ending on March 30, 这一期间（包括头尾两天）
both dates inclusive.
（四）理解和运用商业术语
一般常用的商业用语用字简洁，意义明确，使用得好，工作进行得顺利，使用得不好，就会引起混乱，误解，甚至产生不必要的纠纷，如：
You ask very short delivery for your order.
写信的人原意是说“你们要求赶快交你们的定货。”
可是short delivery不是快点交货的意思，而是“短交”的意思，这就用错了商业术语。因此，应该说：
Your require quick(prompt) delivery of your order.
（五）合适的写作技巧或方法，以及正确运用其他的六个"Ｃ"
(1)、非英语国家的人学英语中普遍的弱点之一是不能正确地拼写（spelling）每一个英文字。拼写正确与否是一个很重要的问题。有时，一不小心，拼写错了，会误大事或出笑话。 你想买靴子，英文应该是BOOTS，要是拼写成BOATS就变成你想买船了。
怎样才能正确地拼写？最好的办法是读得仔细，注意每个字的正确拼法及字母排列。要注意
音节(syllables)
字根(roots)
前缀(prefixes)
后缀(suffixes)
有人就此写了首打油诗做了个“总结”
I before E
Except after C
Or when sounded as A
As in neighbor or weigh.
其基本意思是说除了在字母C之后或是发音是[ei ]之外，通常是I在E之前。现举例说明：
(a) ie [发音i:]
achieve， grieve， retrieve
believe， niece， shield
brief， piece， shriek
chief， pier， siege
field， pierce， thief
fiend， relieve， wield
fierce， reprieve， yield
(b) ei [发音i:]
ceiling, conceive, deceive, perceive, receive
(c) ei [发音ei]
feint, obeisance, sleigh
freight, reign, veil
inveigh, rein, weigh
neighbor, skein, weight
例外：
either, fiery, foreign, friend, heifer, height, inveigle, leisure, seize, sovereign, weird.
又如以ceed, cede,和sede结尾的动词中，只有三个普通的动词以ceed结尾，即：exceed,proceed和succeed结尾的，如：acced, concede, intercede, precede, recede.
名词的复数形式也得注意，否则也要出错。不过如何把名词的单数变成复数还是有规律的。
（a）绝大部分的名词从单数变为复数时，只要在词尾加个""就行了。如：
hat, hats; acrobat, acrobats; banana, bananas.
（b）单数名词的字尾是s, ch, x或z的复数，通常是加es, 如：mass, masses; patch, patches; tax, taxes; buzz, buzzes.
（c）以y结尾的y前是辅音字母的单数名词变复数时，把y去掉改为I再加es，如：city, cities;community, communities.
（d）以y结尾的y前是元音字母的单数名词变复数时，只要在字尾加s, 如：money, moneys.
（e）以o结尾的而o前是元音字母的单数名词，在字尾加s就变为复数，如：radio, radios.
（f）以o结尾的而o前是辅音字母的单数名词变成复数时，应加es, 如：
buffaloes, calicoes, cargoes, dominoes, echoes, embargoes, heroes, jingoes, mosquitoes, mottoes(mottos), mulattoes, potatoes, tomatoes, tornadoes, torpedoes, volcanoes.
但有例外如：
banjos, bolos, cantos, contraltos, dynamos, gigolos, octaves, pianos, quartos, silos, solos, sopranos, zeros.
（g）绝大多数以f结尾的名词，从单数变为复数时，把f换成v再加上es，如：half, halves, scarf, scarves(or : scarfs) ; self, selves ; sheaf, sheaves ; thief, thieves ; wolf, wolves.
但有例外如：
beliefs, chiefs, dwarfs, griefs, handkerchiefs, hoofs, mischiefs, roofs, staffs
（h）专有名词一般在字尾加s，构成复数，但以ch, s, x或z结尾的专有名词，则要加es如：
the Kellys, the six Marys, the Finleys, the Harrises, the Foxes, the Heinzes.
（i）字母，数字，记号或其他作这种用途的字的复数形式是在字尾加"s"，如：three m''s; two''s; if''s and and''s.
（j）某些外来字还保留其原来的复数形式：
agendum------agenda focus----------foci
alumna-------alumnae locus----------loci
alumnus------alumni hypothesis-----hypotheses
analysis-----analyses larva----------larvae
axis---------axes parenthesis----parenteses
bacterium----bacteria phenomenon-----phenomena
basis--------bases radius---------radii
chassis------chassis stratum--------strata
crisis-------crises tableau--------tableaux
datum--------data thesis---------theses
复合名词的复数通常是其中的主要字用复数形式，如：
fathers-in-law; hangers-on; passers-by; by-standers; solicitors general; attorneys general(or: attorney generals); major generals; Knights Templar.
但也有都用复数形式的，如：
nanservant, menservants; woman-servant, women-servants
以上例子说明，英语的拼写是有一定规律的，只是多加注意，便可以逐渐掌握其规律。但是，任何规律都有其相对的例外，这就需要特别下工夫。
有人把这些不规则的内容编了一首打油诗，现转录下来，供参考。
We''ll begin with a box and the plural is boxes,
But the plural of ox should be oxen not oxes.
Then one fowl is a goose but two are called geese,
Yet the plural of mouse should never be meese.
You may find a lone mouse or a whole set of mice,
But the plural of house is houses not hice,
If the plural of man is always called men,
Shouldn''t the plural o a pan be called pen?
If I speak of a foot and you show me your feet,
And I give you a boot would a pare be called beet?
If one is a tooth and whole set are teeth,
Why should not the plural of booth be called beeth?
Then one may be that and three would be those,
Yet hat in that plural wouldn''t be hose.
And the plural of cat is cats and not cose.
We speak of a brother and also of brethren,
But though we say Mother we never say Methren,
Then the masculine pronouns are he, his, and him,
But imagine the feminine, she, shis, and shim.
So English I fancy, you all will agree,
Is the funniest language you ever did see.
(2)、正确使用大写（Capital Letter）
一般在每一句，每一个直接引语，每一行诗的第一个字要大写，人的称呼或头衔，书名等要大写，专有名词要大写，月名，星期几要大写，代词Ｉ要大写。这是使用英语必须具备的起码的知识。因此，大写使用的正确与否，也是英语水平问题。
除了上述一般大写规律以外，在商业书信英语中的大写，还有其本身的特点，现说明于下：
（Ａ）North, South, East, West
这四个字作为一般方向用时小写， 但是当它们作为一个地理概念表示北方地区，南方地区，东方地区，西方地区，或专有的地名联用时，就必须大写。
例：Cotton is the principal crop in the South; it is also grown extensively in the Southwest and in the Sou thern California
(棉花是南部各州的重要作物，西南各州和加利福尼亚南部也广泛种植。)
（Ｂ）商品名称
从语法上讲，一般的商品名称（非专有名词）没有必要大写。在商业书信中为了强调（）或要促使对方注意，商品名称常常大写。
例：We have seen your advertisement in the "Textile World" and should be glad if you would send us patterns of Ladies'' Woolens with your best terms.
(我们看到你们在"织物界"杂志上的广告，请寄妇女用毛织物样本并告最优惠的价格条件。)
（Ｃ）文件名称
例：we have quoted our best terms on the enclosed Price List.
（我们已随函寄送价目表报最优惠价格条件。）
( D ) 公司，团体，城市名称省略时大写
例：The Company will pay you $100 annuity.
该公司将付给你年金100美圆。
本文来自作文地带：http://www.liuxuepaper.com/
（Ｅ）职务名称
例：There is enclosed a letter from Mr. H.A.Anderson, President, National City Bank of New York.
(同函俯上花旗银行行长安得逊先生所写书信一封。)
（Ｆ）船名
例：We have shipped the goods by the m.v."London Maru" of OSK.
（货已由大阪轮船公司的“伦敦丸”轮装运。）
小编建议：英语作文