Rules of writing a business letter：Completeness（完整）  Concreteness（具体）Correctness（正确）  Brachylogy（简洁） Clearness（明晰） Courtesy（礼貌）Sincerity（诚意）

1.         The address and date

Basically, you can line up all addresses, date, and salutation on the left-hand margin. Also it is acceptable to write your address above the date in the top right-hand corner of the letter if it isn't printed on the letterhead (信封上的指定填写位置), then write below it and on the left the full name and address of the person or company to whom you are sending the letter.

2.         The salutation

This is the phrase which is used to start the letter. In English, it is followed by a colon, but you can use comma if the letter is very informal. Here are some of the common ways of starting a business letter.

a)         To a company: you can use “To whom it may concern:”

b)         To an individual:

                       i.              If you don’t know the name of the person:     Dear Sir: or Dear Madam:

                     ii.              If you don’t know whether the person is male or female:        Dear Sir or Madam:

                    iii.              If you know the name:      Dear Mr. black: or Dear Ms. Brown: