一般人可能认为美语比较随意，较口语化。其实，在许多正式场合，美语也会“板起脸来”，一本正经。
法官、律师、政府及大公司高官们在“笔谈”时，用的往往就是这种“板起脸来”的美语。比如，某一活动的主办者接到信询问能否派更多人参加活动。主办者完全可用以下几句简单的话把事情说清楚：
Dear Sir or Madam：
Thank you for your letter of September 30th, XXXX. In your letter you asked if more people could come to our activity. We'll check and let you know one way or the other.
然而，如果主办者是个大单位，很可能回信就成了下面这样：
Dear Sir or Madam：
This is to acknowledge that we are in receipt of your correspondence dated September 30th, XXXX. The request concerning the participation of additional attendees in your previous missive may require the oversight of our department concerned, which will notify you of its decision after examination of seat availability. Should capacity becomes an issue, your indulgence is most appreciated.
从第二封信可看出，在词义和词性的选择上，作者都倾向于正式，甚至有些“装腔作势”。比如，就letter(信函)这么一个简单的词，就分别用了“correspondence”和“missive”等正式说法。另一特点是，正式文体多用名词和被动语态。
正式文体的用途是，去掉不必要的感情色彩，表示郑重其事。比如，你租房子给别人，住户却不付房租，你提醒了3次还毫无效果。你可以写个便条说：You owe me rent and I asked you three times already. If you don't pay it, I will take you to court.
虽然意思表达清楚，但语气像熟人间商量事情。倘若你板起脸来，写下如下文字：
This is to inform you that, despite 3 reminders, no payment of rent has been made to date and if this situation continues, I will be left with no alternative but to start legal proceedings.
这位住户怕是要认真应对了。